moodlelib.php

<?php // $Id$

///////////////////////////////////////////////////////////////////////////
//                                                                       //
// NOTICE OF COPYRIGHT                                                   //
//                                                                       //
// Moodle - Modular Object-Oriented Dynamic Learning Environment         //
//          http://moodle.org                                            //
//                                                                       //
// Copyright (C) 1999-2004  Martin Dougiamas  http://dougiamas.com       //
//                                                                       //
// This program is free software; you can redistribute it and/or modify  //
// it under the terms of the GNU General Public License as published by  //
// the Free Software Foundation; either version 2 of the License, or     //
// (at your option) any later version.                                   //
//                                                                       //
// This program is distributed in the hope that it will be useful,       //
// but WITHOUT ANY WARRANTY; without even the implied warranty of        //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         //
// GNU General Public License for more details:                          //
//                                                                       //
//          http://www.gnu.org/copyleft/gpl.html                         //
//                                                                       //
///////////////////////////////////////////////////////////////////////////

/**
 * moodlelib.php - Moodle main library
 *
 * Main library file of miscellaneous general-purpose Moodle functions.
 * Other main libraries:
 *  - weblib.php      - functions that produce web output
 *  - datalib.php     - functions that access the database
 * @author Martin Dougiamas
 * @version $Id$
 * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
 * @package moodlecore
 */

/// CONSTANTS (Encased in phpdoc proper comments)/////////////////////////

/**
 * Used by some scripts to check they are being called by Moodle
 */
define('MOODLE_INTERNAL', true);

/**
 * No groups used?
 */
define('NOGROUPS', 0);

/**
 * Groups used?
 */
define('SEPARATEGROUPS', 1);

/**
 * Groups visible?
 */
define('VISIBLEGROUPS', 2);

/// Date and time constants ///
/**
 * Time constant - the number of seconds in a year
 */

define('YEARSECS', 31536000);

/**
 * Time constant - the number of seconds in a week
 */
define('WEEKSECS', 604800);

/**
 * Time constant - the number of seconds in a day
 */
define('DAYSECS', 86400);

/**
 * Time constant - the number of seconds in an hour
 */
define('HOURSECS', 3600);

/**
 * Time constant - the number of seconds in a minute
 */
define('MINSECS', 60);

/**
 * Time constant - the number of minutes in a day
 */
define('DAYMINS', 1440);

/**
 * Time constant - the number of minutes in an hour
 */
define('HOURMINS', 60);

/// Parameter constants - every call to optional_param(), required_param()  ///
/// or clean_param() should have a specified type of parameter.  //////////////

/**
 * PARAM_RAW specifies a parameter that is not cleaned/processed in any way;
 * originally was 0, but changed because we need to detect unknown
 * parameter types and swiched order in clean_param().
 */
define('PARAM_RAW', 666);

/**
 * PARAM_CLEAN - obsoleted, please try to use more specific type of parameter.
 * It was one of the first types, that is why it is abused so much ;-)
 */
define('PARAM_CLEAN',    0x0001);

/**
 * PARAM_INT - integers only, use when expecting only numbers.
 */
define('PARAM_INT',      0x0002);

/**
 * PARAM_INTEGER - an alias for PARAM_INT
 */
define('PARAM_INTEGER',  0x0002);

/**
 * PARAM_NUMBER - a real/floating point number.
 */
define('PARAM_NUMBER',  0x000a);

/**
 * PARAM_ALPHA - contains only english letters.
 */
define('PARAM_ALPHA',    0x0004);

/**
 * PARAM_ACTION - an alias for PARAM_ALPHA, use for various actions in formas and urls
 * @TODO: should we alias it to PARAM_ALPHANUM ?
 */
define('PARAM_ACTION',   0x0004);

/**
 * PARAM_FORMAT - an alias for PARAM_ALPHA, use for names of plugins, formats, etc.
 * @TODO: should we alias it to PARAM_ALPHANUM ?
 */
define('PARAM_FORMAT',   0x0004);

/**
 * PARAM_NOTAGS - all html tags are stripped from the text. Do not abuse this type.
 */
define('PARAM_NOTAGS',   0x0008);

 /**
 * PARAM_MULTILANG - alias of PARAM_TEXT.
 */
define('PARAM_MULTILANG',  0x0009);

 /**
 * PARAM_TEXT - general plain text compatible with multilang filter, no other html tags.
 */
define('PARAM_TEXT',  0x0009);

/**
 * PARAM_FILE - safe file name, all dangerous chars are stripped, protects against XSS, SQL injections and directory traversals
 */
define('PARAM_FILE',     0x0010);

/**
 * PARAM_PATH - safe relative path name, all dangerous chars are stripped, protects against XSS, SQL injections and directory traversals
 * note: the leading slash is not removed, window drive letter is not allowed
 */
define('PARAM_PATH',     0x0020);

/**
 * PARAM_HOST - expected fully qualified domain name (FQDN) or an IPv4 dotted quad (IP address)
 */
define('PARAM_HOST',     0x0040);

/**
 * PARAM_URL - expected properly formatted URL.
 */
define('PARAM_URL',      0x0080);

/**
 * PARAM_LOCALURL - expected properly formatted URL as well as one that refers to the local server itself. (NOT orthogonal to the others! Implies PARAM_URL!)
 */
define('PARAM_LOCALURL', 0x0180);

/**
 * PARAM_CLEANFILE - safe file name, all dangerous and regional chars are removed,
 * use when you want to store a new file submitted by students
 */
define('PARAM_CLEANFILE',0x0200);

/**
 * PARAM_ALPHANUM - expected numbers and letters only.
 */
define('PARAM_ALPHANUM', 0x0400);

/**
 * PARAM_BOOL - converts input into 0 or 1, use for switches in forms and urls.
 */
define('PARAM_BOOL',     0x0800);

/**
 * PARAM_CLEANHTML - cleans submitted HTML code and removes slashes
 * note: do not forget to addslashes() before storing into database!
 */
define('PARAM_CLEANHTML',0x1000);

/**
 * PARAM_ALPHAEXT the same contents as PARAM_ALPHA plus the chars in quotes: "/-_" allowed,
 * suitable for include() and require()
 * @TODO: should we rename this function to PARAM_SAFEDIRS??
 */
define('PARAM_ALPHAEXT', 0x2000);

/**
 * PARAM_SAFEDIR - safe directory name, suitable for include() and require()
 */
define('PARAM_SAFEDIR',  0x4000);

/**
 * PARAM_SEQUENCE - expects a sequence of numbers like 8 to 1,5,6,4,6,8,9.  Numbers and comma only.
 */
define('PARAM_SEQUENCE',  0x8000);

/**
 * PARAM_PEM - Privacy Enhanced Mail format
 */
define('PARAM_PEM',      0x10000);

/**
 * PARAM_BASE64 - Base 64 encoded format
 */
define('PARAM_BASE64',   0x20000);


/// Page types ///
/**
 * PAGE_COURSE_VIEW is a definition of a page type. For more information on the page class see moodle/lib/pagelib.php.
 */
define('PAGE_COURSE_VIEW', 'course-view');

/// Debug levels ///
/** no warnings at all */
define ('DEBUG_NONE', 0);
/** E_ERROR | E_PARSE */
define ('DEBUG_MINIMAL', 5);
/** E_ERROR | E_PARSE | E_WARNING | E_NOTICE */
define ('DEBUG_NORMAL', 15);
/** E_ALL without E_STRICT and E_RECOVERABLE_ERROR for now */
define ('DEBUG_ALL', 2047);
/** DEBUG_ALL with extra Moodle debug messages - (DEBUG_ALL | 32768) */
define ('DEBUG_DEVELOPER', 34815);

/**
 * Blog access level constant declaration
 */
define ('BLOG_USER_LEVEL', 1);
define ('BLOG_GROUP_LEVEL', 2);
define ('BLOG_COURSE_LEVEL', 3);
define ('BLOG_SITE_LEVEL', 4);
define ('BLOG_GLOBAL_LEVEL', 5);



/// PARAMETER HANDLING ////////////////////////////////////////////////////

/**
 * Returns a particular value for the named variable, taken from
 * POST or GET.  If the parameter doesn't exist then an error is
 * thrown because we require this variable.
 *
 * This function should be used to initialise all required values
 * in a script that are based on parameters.  Usually it will be
 * used like this:
 *    $id = required_param('id');
 *
 * @param string $parname the name of the page parameter we want
 * @param int $type expected type of parameter
 * @return mixed
 */
function required_param($parname, $type=PARAM_CLEAN) {

    // detect_unchecked_vars addition
    global $CFG;
    if (!empty($CFG->detect_unchecked_vars)) {
        global $UNCHECKED_VARS;
        unset ($UNCHECKED_VARS->vars[$parname]);
    }

    if (isset($_POST[$parname])) {       // POST has precedence
        $param = $_POST[$parname];
    } else if (isset($_GET[$parname])) {
        $param = $_GET[$parname];
    } else {
        error('A required parameter ('.$parname.') was missing');
    }

    return clean_param($param, $type);
}

/**
 * Returns a particular value for the named variable, taken from
 * POST or GET, otherwise returning a given default.
 *
 * This function should be used to initialise all optional values
 * in a script that are based on parameters.  Usually it will be
 * used like this:
 *    $name = optional_param('name', 'Fred');
 *
 * @param string $parname the name of the page parameter we want
 * @param mixed  $default the default value to return if nothing is found
 * @param int $type expected type of parameter
 * @return mixed
 */
function optional_param($parname, $default=NULL, $type=PARAM_CLEAN) {

    // detect_unchecked_vars addition
    global $CFG;
    if (!empty($CFG->detect_unchecked_vars)) {
        global $UNCHECKED_VARS;
        unset ($UNCHECKED_VARS->vars[$parname]);
    }

    if (isset($_POST[$parname])) {       // POST has precedence
        $param = $_POST[$parname];
    } else if (isset($_GET[$parname])) {
        $param = $_GET[$parname];
    } else {
        return $default;
    }

    return clean_param($param, $type);
}

/**
 * Used by {@link optional_param()} and {@link required_param()} to
 * clean the variables and/or cast to specific types, based on
 * an options field.
 * <code>
 * $course->format = clean_param($course->format, PARAM_ALPHA);
 * $selectedgrade_item = clean_param($selectedgrade_item, PARAM_CLEAN);
 * </code>
 *
 * @uses $CFG
 * @uses PARAM_CLEAN
 * @uses PARAM_INT
 * @uses PARAM_INTEGER
 * @uses PARAM_ALPHA
 * @uses PARAM_ALPHANUM
 * @uses PARAM_NOTAGS
 * @uses PARAM_ALPHAEXT
 * @uses PARAM_BOOL
 * @uses PARAM_SAFEDIR
 * @uses PARAM_CLEANFILE
 * @uses PARAM_FILE
 * @uses PARAM_PATH
 * @uses PARAM_HOST
 * @uses PARAM_URL
 * @uses PARAM_LOCALURL
 * @uses PARAM_CLEANHTML
 * @uses PARAM_SEQUENCE
 * @param mixed $param the variable we are cleaning
 * @param int $type expected format of param after cleaning.
 * @return mixed
 */
function clean_param($param, $type) {

    global $CFG;

    if (is_array($param)) {              // Let's loop
        $newparam = array();
        foreach ($param as $key => $value) {
            $newparam[$key] = clean_param($value, $type);
        }
        return $newparam;
    }

    switch ($type) {
        case PARAM_RAW:          // no cleaning at all
            return $param;

        case PARAM_CLEAN:        // General HTML cleaning, try to use more specific type if possible
            if (is_numeric($param)) {
                return $param;
            }
            $param = stripslashes($param);   // Needed for kses to work fine
            $param = clean_text($param);     // Sweep for scripts, etc
            return addslashes($param);       // Restore original request parameter slashes

        case PARAM_CLEANHTML:    // prepare html fragment for display, do not store it into db!!
            $param = stripslashes($param);   // Remove any slashes
            $param = clean_text($param);     // Sweep for scripts, etc
            return trim($param);

        case PARAM_INT:
            return (int)$param;  // Convert to integer

        case PARAM_NUMBER:
            return (float)$param;  // Convert to integer

        case PARAM_ALPHA:        // Remove everything not a-z
            return eregi_replace('[^a-zA-Z]', '', $param);

        case PARAM_ALPHANUM:     // Remove everything not a-zA-Z0-9
            return eregi_replace('[^A-Za-z0-9]', '', $param);

        case PARAM_ALPHAEXT:     // Remove everything not a-zA-Z/_-
            return eregi_replace('[^a-zA-Z/_-]', '', $param);

        case PARAM_SEQUENCE:     // Remove everything not 0-9,
            return eregi_replace('[^0-9,]', '', $param);

        case PARAM_BOOL:         // Convert to 1 or 0
            $tempstr = strtolower($param);
            if ($tempstr == 'on' or $tempstr == 'yes' ) {
                $param = 1;
            } else if ($tempstr == 'off' or $tempstr == 'no') {
                $param = 0;
            } else {
                $param = empty($param) ? 0 : 1;
            }
            return $param;

        case PARAM_NOTAGS:       // Strip all tags
            return strip_tags($param);

        case PARAM_TEXT:    // leave only tags needed for multilang
            return clean_param(strip_tags($param, '<lang><span>'), PARAM_CLEAN);

        case PARAM_SAFEDIR:      // Remove everything not a-zA-Z0-9_-
            return eregi_replace('[^a-zA-Z0-9_-]', '', $param);

        case PARAM_CLEANFILE:    // allow only safe characters
            return clean_filename($param);

        case PARAM_FILE:         // Strip all suspicious characters from filename
            $param = ereg_replace('[[:cntrl:]]|[<>"`\|\':\\/]', '', $param);
            $param = ereg_replace('\.\.+', '', $param);
            if($param == '.') {
                $param = '';
            }
            return $param;

        case PARAM_PATH:         // Strip all suspicious characters from file path
            $param = str_replace('\\\'', '\'', $param);
            $param = str_replace('\\"', '"', $param);
            $param = str_replace('\\', '/', $param);
            $param = ereg_replace('[[:cntrl:]]|[<>"`\|\':]', '', $param);
            $param = ereg_replace('\.\.+', '', $param);
            $param = ereg_replace('//+', '/', $param);
            return ereg_replace('/(\./)+', '/', $param);

        case PARAM_HOST:         // allow FQDN or IPv4 dotted quad
            preg_replace('/[^\.\d\w-]/','', $param ); // only allowed chars
            // match ipv4 dotted quad
            if (preg_match('/(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})/',$param, $match)){
                // confirm values are ok
                if ( $match[0] > 255
                     || $match[1] > 255
                     || $match[3] > 255
                     || $match[4] > 255 ) {
                    // hmmm, what kind of dotted quad is this?
                    $param = '';
                }
            } elseif ( preg_match('/^[\w\d\.-]+$/', $param) // dots, hyphens, numbers
                       && !preg_match('/^[\.-]/',  $param) // no leading dots/hyphens
                       && !preg_match('/[\.-]$/',  $param) // no trailing dots/hyphens
                       ) {
                // all is ok - $param is respected
            } else {
                // all is not ok...
                $param='';
            }
            return $param;

        case PARAM_URL:          // allow safe ftp, http, mailto urls
            include_once($CFG->dirroot . '/lib/validateurlsyntax.php');
            if (!empty($param) && validateUrlSyntax($param, 's?H?S?F?E?u-P-a?I?p?f?q?r?')) {
                // all is ok, param is respected
            } else {
                $param =''; // not really ok
            }
            return $param;

        case PARAM_LOCALURL:     // allow http absolute, root relative and relative URLs within wwwroot
            $param = clean_param($param, PARAM_URL);
            if (!empty($param)) {
                if (preg_match(':^/:', $param)) {
                    // root-relative, ok!
                } elseif (preg_match('/^'.preg_quote($CFG->wwwroot, '/').'/i',$param)) {
                    // absolute, and matches our wwwroot
                } else {
                    // relative - let's make sure there are no tricks
                    if (validateUrlSyntax($param, 's-u-P-a-p-f+q?r?')) {
                        // looks ok.
                    } else {
                        $param = '';
                    }
                }
            }
            return $param;
        case PARAM_PEM:
            $param = trim($param);
            // PEM formatted strings may contain letters/numbers and the symbols
            // forward slash: /
            // plus sign:     +
            // equal sign:    =
            // , surrounded by BEGIN and END CERTIFICATE prefix and suffixes
            if (preg_match('/^-----BEGIN CERTIFICATE-----([\s\w\/\+=]+)-----END CERTIFICATE-----$/', trim($param), $matches)) {
                list($wholething, $body) = $matches;
                unset($wholething, $matches);
                $b64 = clean_param($body, PARAM_BASE64);
                if (!empty($b64)) {
                    return "-----BEGIN CERTIFICATE-----\n$b64\n-----END CERTIFICATE-----\n";
                } else {
                    return '';
                }
            }
            return '';
        case PARAM_BASE64:
            if (!empty($param)) {
                // PEM formatted strings may contain letters/numbers and the symbols
                // forward slash: /
                // plus sign:     +
                // equal sign:    =
                if (0 >= preg_match('/^([\s\w\/\+=]+)$/', trim($param))) {
                    return '';
                }
                $lines = preg_split('/[\s]+/', $param, -1, PREG_SPLIT_NO_EMPTY);
                // Each line of base64 encoded data must be 64 characters in
                // length, except for the last line which may be less than (or
                // equal to) 64 characters long.
                for ($i=0, $j=count($lines); $i < $j; $i++) {
                    if ($i + 1 == $j) {
                        if (64 < strlen($lines[$i])) {
                            return '';
                        }
                        continue;
                    }

                    if (64 != strlen($lines[$i])) {
                        return '';
                    }
                }
                return implode("\n",$lines);
            } else {
                return '';
            }
        default:                 // throw error, switched parameters in optional_param or another serious problem
            error("Unknown parameter type: $type");
    }
}



/**
 * Set a key in global configuration
 *
 * Set a key/value pair in both this session's {@link $CFG} global variable
 * and in the 'config' database table for future sessions.
 *
 * Can also be used to update keys for plugin-scoped configs in config_plugin table.
 * In that case it doesn't affect $CFG.
 *
 * @param string $name the key to set
 * @param string $value the value to set (without magic quotes)
 * @param string $plugin (optional) the plugin scope
 * @uses $CFG
 * @return bool
 */
function set_config($name, $value, $plugin=NULL) {
/// No need for get_config because they are usually always available in $CFG

    global $CFG;

    if (empty($plugin)) {
        $CFG->$name = $value;  // So it's defined for this invocation at least

        if (get_field('config', 'name', 'name', $name)) {
            return set_field('config', 'value', addslashes($value), 'name', $name);
        } else {
            $config = new object();
            $config->name = $name;
            $config->value = addslashes($value);
            return insert_record('config', $config);
        }
    } else { // plugin scope
        if ($id = get_field('config_plugins', 'id', 'name', $name, 'plugin', $plugin)) {
            return set_field('config_plugins', 'value', addslashes($value), 'id', $id);
        } else {
            $config = new object();
            $config->plugin = addslashes($plugin);
            $config->name   = $name;
            $config->value  = addslashes($value);
            return insert_record('config_plugins', $config);
        }
    }
}

/**
 * Get configuration values from the global config table
 * or the config_plugins table.
 *
 * If called with no parameters it will do the right thing
 * generating $CFG safely from the database without overwriting
 * existing values.
 *
 * If called with 2 parameters it will return a $string single
 * value or false of the value is not found.
 *
 * @param string $plugin
 * @param string $name
 * @uses $CFG
 * @return hash-like object or single value
 *
 */
function get_config($plugin=NULL, $name=NULL) {

    global $CFG;

    if (!empty($name)) { // the user is asking for a specific value
        if (!empty($plugin)) {
            return get_field('config_plugins', 'value', 'plugin' , $plugin, 'name', $name);
        } else {
            return get_field('config', 'value', 'name', $name);
        }
    }

    // the user is after a recordset
    if (!empty($plugin)) {
        if ($configs=get_records('config_plugins', 'plugin', $plugin, '', 'name,value')) {
            $configs = (array)$configs;
            $localcfg = array();
            foreach ($configs as $config) {
                $localcfg[$config->name] = $config->value;
            }
            return (object)$localcfg;
        } else {
            return false;
        }
    } else {
        // this was originally in setup.php
        if ($configs = get_records('config')) {
            $localcfg = (array)$CFG;
            foreach ($configs as $config) {
                if (!isset($localcfg[$config->name])) {
                    $localcfg[$config->name] = $config->value;
                } else {
                    if ($localcfg[$config->name] != $config->value ) {
                        // complain if the DB has a different
                        // value than config.php does
                        error_log("\$CFG->{$config->name} in config.php ({$localcfg[$config->name]}) overrides database setting ({$config->value})");
                    }
                }
            }

            $localcfg = (object)$localcfg;
            return $localcfg;
        } else {
            // preserve $CFG if DB returns nothing or error
            return $CFG;
        }

    }
}

/**
 * Removes a key from global configuration
 *
 * @param string $name the key to set
 * @param string $plugin (optional) the plugin scope
 * @uses $CFG
 * @return bool
 */
function unset_config($name, $plugin=NULL) {

    global $CFG;

    unset($CFG->$name);

    if (empty($plugin)) {
        return delete_records('config', 'name', $name);
    } else {
        return delete_records('config_plugins', 'name', $name, 'plugin', $plugin);
    }
}


/**
 * Refresh current $USER session global variable with all their current preferences.
 * @uses $USER
 */
function reload_user_preferences() {

    global $USER;

    //reset preference
    $USER->preference = array();

    if (!isloggedin() or isguestuser()) {
        // no pernament storage for not-logged-in user and guest

    } else if ($preferences = get_records('user_preferences', 'userid', $USER->id)) {
        foreach ($preferences as $preference) {
            $USER->preference[$preference->name] = $preference->value;
        }
    }

    return true;
}

/**
 * Sets a preference for the current user
 * Optionally, can set a preference for a different user object
 * @uses $USER
 * @todo Add a better description and include usage examples. Add inline links to $USER and user functions in above line.

 * @param string $name The key to set as preference for the specified user
 * @param string $value The value to set forthe $name key in the specified user's record
 * @param int $otheruserid A moodle user ID
 * @return bool
 */
function set_user_preference($name, $value, $otheruserid=NULL) {

    global $USER;

    if (!isset($USER->preference)) {
        reload_user_preferences();
    }

    if (empty($name)) {
        return false;
    }

    $nostore = false;

    if (empty($otheruserid)){
        if (!isloggedin() or isguestuser()) {
            $nostore = true;
        }
        $userid = $USER->id;
    } else {
        if (isguestuser($otheruserid)) {
            $nostore = true;
        }
        $userid = $otheruserid;
    }

    $return = true;
    if ($nostore) {
        // no pernament storage for not-logged-in user and guest

    } else if ($preference = get_record('user_preferences', 'userid', $userid, 'name', addslashes($name))) {
        if (!set_field('user_preferences', 'value', addslashes((string)$value), 'id', $preference->id)) {
            $return = false;
        }

    } else {
        $preference = new object();
        $preference->userid = $userid;
        $preference->name   = addslashes($name);
        $preference->value  = addslashes((string)$value);
        if (!insert_record('user_preferences', $preference)) {
            $return = false;
        }
    }

    // update value in USER session if needed
    if ($userid == $USER->id) {
        $USER->preference[$name] = (string)$value;
    }

    return $return;
}

/**
 * Unsets a preference completely by deleting it from the database
 * Optionally, can set a preference for a different user id
 * @uses $USER
 * @param string  $name The key to unset as preference for the specified user
 * @param int $otheruserid A moodle user ID
 */
function unset_user_preference($name, $otheruserid=NULL) {

    global $USER;

    if (!isset($USER->preference)) {
        reload_user_preferences();
    }

    if (empty($otheruserid)){
        $userid = $USER->id;
    } else {
        $userid = $otheruserid;
    }

    //Delete the preference from $USER if needed
    if ($userid == $USER->id) {
        unset($USER->preference[$name]);
    }

    //Then from DB
    return delete_records('user_preferences', 'userid', $userid, 'name', addslashes($name));
}


/**
 * Sets a whole array of preferences for the current user
 * @param array $prefarray An array of key/value pairs to be set
 * @param int $otheruserid A moodle user ID
 * @return bool
 */
function set_user_preferences($prefarray, $otheruserid=NULL) {

    if (!is_array($prefarray) or empty($prefarray)) {
        return false;
    }

    $return = true;
    foreach ($prefarray as $name => $value) {
        // The order is important; test for return is done first
        $return = (set_user_preference($name, $value, $otheruserid) && $return);
    }
    return $return;
}

/**
 * If no arguments are supplied this function will return
 * all of the current user preferences as an array.
 * If a name is specified then this function
 * attempts to return that particular preference value.  If
 * none is found, then the optional value $default is returned,
 * otherwise NULL.
 * @param string $name Name of the key to use in finding a preference value
 * @param string $default Value to be returned if the $name key is not set in the user preferences
 * @param int $otheruserid A moodle user ID
 * @uses $USER
 * @return string
 */
function get_user_preferences($name=NULL, $default=NULL, $otheruserid=NULL) {
    global $USER;

    if (!isset($USER->preference)) {
        reload_user_preferences();
    }

    if (empty($otheruserid)){
        $userid = $USER->id;
    } else {
        $userid = $otheruserid;
    }

    if ($userid == $USER->id) {
        $preference = $USER->preference;

    } else {
        $preference = array();
        if ($prefdata = get_records('user_preferences', 'userid', $userid)) {
            foreach ($prefdata as $pref) {
                $preference[$pref->name] = $pref->value;
            }
        }
    }

    if (empty($name)) {
        return $preference;            // All values

    } else if (array_key_exists($name, $preference)) {
        return $preference[$name];    // The single value

    } else {
        return $default;              // Default value (or NULL)
    }
}


/// FUNCTIONS FOR HANDLING TIME ////////////////////////////////////////////

/**
 * Given date parts in user time produce a GMT timestamp.
 *
 * @param int $year The year part to create timestamp of
 * @param int $month The month part to create timestamp of
 * @param int $day The day part to create timestamp of
 * @param int $hour The hour part to create timestamp of
 * @param int $minute The minute part to create timestamp of
 * @param int $second The second part to create timestamp of
 * @param float $timezone ?
 * @param bool $applydst ?
 * @return int timestamp
 * @todo Finish documenting this function
 */
function make_timestamp($year, $month=1, $day=1, $hour=0, $minute=0, $second=0, $timezone=99, $applydst=true) {

    $timezone = get_user_timezone_offset($timezone);

    if (abs($timezone) > 13) {
        $time = mktime((int)$hour, (int)$minute, (int)$second, (int)$month, (int)$day, (int)$year);
    } else {
        $time = gmmktime((int)$hour, (int)$minute, (int)$second, (int)$month, (int)$day, (int)$year);
        $time = usertime($time, $timezone);
        if($applydst) {
            $time -= dst_offset_on($time);
        }
    }

    return $time;

}

/**
 * Given an amount of time in seconds, returns string
 * formatted nicely as weeks, days, hours etc as needed
 *
 * @uses MINSECS
 * @uses HOURSECS
 * @uses DAYSECS
 * @uses YEARSECS
 * @param int $totalsecs ?
 * @param array $str ?
 * @return string
 */
 function format_time($totalsecs, $str=NULL) {

    $totalsecs = abs($totalsecs);

    if (!$str) {  // Create the str structure the slow way
        $str->day   = get_string('day');
        $str->days  = get_string('days');
        $str->hour  = get_string('hour');
        $str->hours = get_string('hours');
        $str->min   = get_string('min');
        $str->mins  = get_string('mins');
        $str->sec   = get_string('sec');
        $str->secs  = get_string('secs');
        $str->year  = get_string('year');
        $str->years = get_string('years');
    }


    $years     = floor($totalsecs/YEARSECS);
    $remainder = $totalsecs - ($years*YEARSECS);
    $days      = floor($remainder/DAYSECS);
    $remainder = $totalsecs - ($days*DAYSECS);
    $hours     = floor($remainder/HOURSECS);
    $remainder = $remainder - ($hours*HOURSECS);
    $mins      = floor($remainder/MINSECS);
    $secs      = $remainder - ($mins*MINSECS);

    $ss = ($secs == 1)  ? $str->sec  : $str->secs;
    $sm = ($mins == 1)  ? $str->min  : $str->mins;
    $sh = ($hours == 1) ? $str->hour : $str->hours;
    $sd = ($days == 1)  ? $str->day  : $str->days;
    $sy = ($years == 1)  ? $str->year  : $str->years;

    $oyears = '';
    $odays = '';
    $ohours = '';
    $omins = '';
    $osecs = '';

    if ($years)  $oyears  = $years .' '. $sy;
    if ($days)  $odays  = $days .' '. $sd;
    if ($hours) $ohours = $hours .' '. $sh;
    if ($mins)  $omins  = $mins .' '. $sm;
    if ($secs)  $osecs  = $secs .' '. $ss;

    if ($years) return trim($oyears .' '. $odays);
    if ($days)  return trim($odays .' '. $ohours);
    if ($hours) return trim($ohours .' '. $omins);
    if ($mins)  return trim($omins .' '. $osecs);
    if ($secs)  return $osecs;
    return get_string('now');
}

/**
 * Returns a formatted string that represents a date in user time
 * <b>WARNING: note that the format is for strftime(), not date().</b>
 * Because of a bug in most Windows time libraries, we can't use
 * the nicer %e, so we have to use %d which has leading zeroes.
 * A lot of the fuss in the function is just getting rid of these leading
 * zeroes as efficiently as possible.
 *
 * If parameter fixday = true (default), then take off leading
 * zero from %d, else mantain it.
 *
 * @uses HOURSECS
 * @param  int $date timestamp in GMT
 * @param string $format strftime format
 * @param float $timezone
 * @param bool $fixday If true (default) then the leading
 * zero from %d is removed. If false then the leading zero is mantained.
 * @return string
 */
function userdate($date, $format='', $timezone=99, $fixday = true) {

    global $CFG;

    if (empty($format)) {
        $format = get_string('strftimedaydatetime');
    }

    if (!empty($CFG->nofixday)) {  // Config.php can force %d not to be fixed.
        $fixday = false;
    } else if ($fixday) {
        $formatnoday = str_replace('%d', 'DD', $format);
        $fixday = ($formatnoday != $format);
    }

    $date += dst_offset_on($date);

    $timezone = get_user_timezone_offset($timezone);

    if (abs($timezone) > 13) {   /// Server time
        if ($fixday) {
            $datestring = strftime($formatnoday, $date);
            $daystring  = str_replace(' 0', '', strftime(' %d', $date));
            $datestring = str_replace('DD', $daystring, $datestring);
        } else {
            $datestring = strftime($format, $date);
        }
    } else {
        $date += (int)($timezone * 3600);
        if ($fixday) {
            $datestring = gmstrftime($formatnoday, $date);
            $daystring  = str_replace(' 0', '', gmstrftime(' %d', $date));
            $datestring = str_replace('DD', $daystring, $datestring);
        } else {
            $datestring = gmstrftime($format, $date);
        }
    }

/// If we are running under Windows convert from windows encoding to UTF-8
/// (because it's impossible to specify UTF-8 to fetch locale info in Win32)

   if ($CFG->ostype == 'WINDOWS') {
       if ($localewincharset = get_string('localewincharset')) {
           $textlib = textlib_get_instance();
           $datestring = $textlib->convert($datestring, $localewincharset, 'utf-8');
       }
   }

    return $datestring;
}

/**
 * Given a $time timestamp in GMT (seconds since epoch),
 * returns an array that represents the date in user time
 *
 * @uses HOURSECS
 * @param int $time Timestamp in GMT
 * @param float $timezone ?
 * @return array An array that represents the date in user time
 * @todo Finish documenting this function
 */
function usergetdate($time, $timezone=99) {

    $timezone = get_user_timezone_offset($timezone);

    if (abs($timezone) > 13) {    // Server time
        return getdate($time);
    }

    // There is no gmgetdate so we use gmdate instead
    $time += dst_offset_on($time);
    $time += intval((float)$timezone * HOURSECS);

    $datestring = gmstrftime('%S_%M_%H_%d_%m_%Y_%w_%j_%A_%B', $time);

    list(
        $getdate['seconds'],
        $getdate['minutes'],
        $getdate['hours'],
        $getdate['mday'],
        $getdate['mon'],
        $getdate['year'],
        $getdate['wday'],
        $getdate['yday'],
        $getdate['weekday'],
        $getdate['month']
    ) = explode('_', $datestring);

    return $getdate;
}

/**
 * Given a GMT timestamp (seconds since epoch), offsets it by
 * the timezone.  eg 3pm in India is 3pm GMT - 7 * 3600 seconds
 *
 * @uses HOURSECS
 * @param  int $date Timestamp in GMT
 * @param float $timezone
 * @return int
 */
function usertime($date, $timezone=99) {

    $timezone = get_user_timezone_offset($timezone);

    if (abs($timezone) > 13) {
        return $date;
    }
    return $date - (int)($timezone * HOURSECS);
}

/**
 * Given a time, return the GMT timestamp of the most recent midnight
 * for the current user.
 *
 * @param int $date Timestamp in GMT
 * @param float $timezone ?
 * @return ?
 */
function usergetmidnight($date, $timezone=99) {

    $timezone = get_user_timezone_offset($timezone);
    $userdate = usergetdate($date, $timezone);

    // Time of midnight of this user's day, in GMT
    return make_timestamp($userdate['year'], $userdate['mon'], $userdate['mday'], 0, 0, 0, $timezone);

}

/**
 * Returns a string that prints the user's timezone
 *
 * @param float $timezone The user's timezone
 * @return string
 */
function usertimezone($timezone=99) {

    $tz = get_user_timezone($timezone);

    if (!is_float($tz)) {
        return $tz;
    }

    if(abs($tz) > 13) { // Server time
        return get_string('serverlocaltime');
    }

    if($tz == intval($tz)) {
        // Don't show .0 for whole hours
        $tz = intval($tz);
    }

    if($tz == 0) {
        return 'UTC';
    }
    else if($tz > 0) {
        return 'UTC+'.$tz;
    }
    else {
        return 'UTC'.$tz;
    }

}

/**
 * Returns a float which represents the user's timezone difference from GMT in hours
 * Checks various settings and picks the most dominant of those which have a value
 *
 * @uses $CFG
 * @uses $USER
 * @param float $tz If this value is provided and not equal to 99, it will be returned as is and no other settings will be checked
 * @return int
 */
function get_user_timezone_offset($tz = 99) {

    global $USER, $CFG;

    $tz = get_user_timezone($tz);

    if (is_float($tz)) {
        return $tz;
    } else {
        $tzrecord = get_timezone_record($tz);
        if (empty($tzrecord)) {
            return 99.0;
        }
        return (float)$tzrecord->gmtoff / HOURMINS;
    }
}

/**
 * Returns a float or a string which denotes the user's timezone
 * A float value means that a simple offset from GMT is used, while a string (it will be the name of a timezone in the database)
 * means that for this timezone there are also DST rules to be taken into account
 * Checks various settings and picks the most dominant of those which have a value
 *
 * @uses $USER
 * @uses $CFG
 * @param float $tz If this value is provided and not equal to 99, it will be returned as is and no other settings will be checked
 * @return mixed
 */
function get_user_timezone($tz = 99) {
    global $USER, $CFG;

    $timezones = array(
        $tz,
        isset($CFG->forcetimezone) ? $CFG->forcetimezone : 99,
        isset($USER->timezone) ? $USER->timezone : 99,
        isset($CFG->timezone) ? $CFG->timezone : 99,
        );

    $tz = 99;

    while(($tz == '' || $tz == 99) && $next = each($timezones)) {
        $tz = $next['value'];
    }

    return is_numeric($tz) ? (float) $tz : $tz;
}

/**
 * ?
 *
 * @uses $CFG
 * @uses $db
 * @param string $timezonename ?
 * @return object
 */
function get_timezone_record($timezonename) {
    global $CFG, $db;
    static $cache = NULL;

    if ($cache === NULL) {
        $cache = array();
    }

    if (isset($cache[$timezonename])) {
        return $cache[$timezonename];
    }

    return $cache[$timezonename] = get_record_sql('SELECT * FROM '.$CFG->prefix.'timezone
                                      WHERE name = '.$db->qstr($timezonename).' ORDER BY year DESC', true);
}

/**
 * ?
 *
 * @uses $CFG
 * @uses $USER
 * @param ? $fromyear ?
 * @param ? $to_year ?
 * @return bool
 */
function calculate_user_dst_table($from_year = NULL, $to_year = NULL) {
    global $CFG, $SESSION;

    $usertz = get_user_timezone();

    if (is_float($usertz)) {
        // Trivial timezone, no DST
        return false;
    }

    if (!empty($SESSION->dst_offsettz) && $SESSION->dst_offsettz != $usertz) {
        // We have precalculated values, but the user's effective TZ has changed in the meantime, so reset
        unset($SESSION->dst_offsets);
        unset($SESSION->dst_range);
    }

    if (!empty($SESSION->dst_offsets) && empty($from_year) && empty($to_year)) {
        // Repeat calls which do not request specific year ranges stop here, we have already calculated the table
        // This will be the return path most of the time, pretty light computationally
        return true;
    }

    // Reaching here means we either need to extend our table or create it from scratch

    // Remember which TZ we calculated these changes for
    $SESSION->dst_offsettz = $usertz;

    if(empty($SESSION->dst_offsets)) {
        // If we 're creating from scratch, put the two guard elements in there
        $SESSION->dst_offsets = array(1 => NULL, 0 => NULL);
    }
    if(empty($SESSION->dst_range)) {
        // If creating from scratch
        $from = max((empty($from_year) ? intval(date('Y')) - 3 : $from_year), 1971);
        $to   = min((empty($to_year)   ? intval(date('Y')) + 3 : $to_year),   2035);

        // Fill in the array with the extra years we need to process
        $yearstoprocess = array();
        for($i = $from; $i <= $to; ++$i) {
            $yearstoprocess[] = $i;
        }

        // Take note of which years we have processed for future calls
        $SESSION->dst_range = array($from, $to);
    }
    else {
        // If needing to extend the table, do the same
        $yearstoprocess = array();

        $from = max((empty($from_year) ? $SESSION->dst_range[0] : $from_year), 1971);
        $to   = min((empty($to_year)   ? $SESSION->dst_range[1] : $to_year),   2035);

        if($from < $SESSION->dst_range[0]) {
            // Take note of which years we need to process and then note that we have processed them for future calls
            for($i = $from; $i < $SESSION->dst_range[0]; ++$i) {
                $yearstoprocess[] = $i;
            }
            $SESSION->dst_range[0] = $from;
        }
        if($to > $SESSION->dst_range[1]) {
            // Take note of which years we need to process and then note that we have processed them for future calls
            for($i = $SESSION->dst_range[1] + 1; $i <= $to; ++$i) {
                $yearstoprocess[] = $i;
            }
            $SESSION->dst_range[1] = $to;
        }
    }

    if(empty($yearstoprocess)) {
        // This means that there was a call requesting a SMALLER range than we have already calculated
        return true;
    }

    // From now on, we know that the array has at least the two guard elements, and $yearstoprocess has the years we need
    // Also, the array is sorted in descending timestamp order!

    // Get DB data
    $presetrecords = get_records('timezone', 'name', $usertz, 'year DESC', 'year, gmtoff, dstoff, dst_month, dst_startday, dst_weekday, dst_skipweeks, dst_time, std_month, std_startday, std_weekday, std_skipweeks, std_time');
    if(empty($presetrecords)) {
        return false;
    }

    // Remove ending guard (first element of the array)
    reset($SESSION->dst_offsets);
    unset($SESSION->dst_offsets[key($SESSION->dst_offsets)]);

    // Add all required change timestamps
    foreach($yearstoprocess as $y) {
        // Find the record which is in effect for the year $y
        foreach($presetrecords as $year => $preset) {
            if($year <= $y) {
                break;
            }
        }

        $changes = dst_changes_for_year($y, $preset);

        if($changes === NULL) {
            continue;
        }
        if($changes['dst'] != 0) {
            $SESSION->dst_offsets[$changes['dst']] = $preset->dstoff * MINSECS;
        }
        if($changes['std'] != 0) {
            $SESSION->dst_offsets[$changes['std']] = 0;
        }
    }

    // Put in a guard element at the top
    $maxtimestamp = max(array_keys($SESSION->dst_offsets));
    $SESSION->dst_offsets[($maxtimestamp + DAYSECS)] = NULL; // DAYSECS is arbitrary, any "small" number will do

    // Sort again
    krsort($SESSION->dst_offsets);

    return true;
}

function dst_changes_for_year($year, $timezone) {

    if($timezone->dst_startday == 0 && $timezone->dst_weekday == 0 && $timezone->std_startday == 0 && $timezone->std_weekday == 0) {
        return NULL;
    }

    $monthdaydst = find_day_in_month($timezone->dst_startday, $timezone->dst_weekday, $timezone->dst_month, $year);
    $monthdaystd = find_day_in_month($timezone->std_startday, $timezone->std_weekday, $timezone->std_month, $year);

    list($dst_hour, $dst_min) = explode(':', $timezone->dst_time);
    list($std_hour, $std_min) = explode(':', $timezone->std_time);

    $timedst = make_timestamp($year, $timezone->dst_month, $monthdaydst, 0, 0, 0, 99, false);
    $timestd = make_timestamp($year, $timezone->std_month, $monthdaystd, 0, 0, 0, 99, false);

    // Instead of putting hour and minute in make_timestamp(), we add them afterwards.
    // This has the advantage of being able to have negative values for hour, i.e. for timezones
    // where GMT time would be in the PREVIOUS day than the local one on which DST changes.

    $timedst += $dst_hour * HOURSECS + $dst_min * MINSECS;
    $timestd += $std_hour * HOURSECS + $std_min * MINSECS;

    return array('dst' => $timedst, 0 => $timedst, 'std' => $timestd, 1 => $timestd);
}

// $time must NOT be compensated at all, it has to be a pure timestamp
function dst_offset_on($time) {
    global $SESSION;

    if(!calculate_user_dst_table() || empty($SESSION->dst_offsets)) {
        return 0;
    }

    reset($SESSION->dst_offsets);
    while(list($from, $offset) = each($SESSION->dst_offsets)) {
        if($from <= $time) {
            break;
        }
    }

    // This is the normal return path
    if($offset !== NULL) {
        return $offset;
    }

    // Reaching this point means we haven't calculated far enough, do it now:
    // Calculate extra DST changes if needed and recurse. The recursion always
    // moves toward the stopping condition, so will always end.

    if($from == 0) {
        // We need a year smaller than $SESSION->dst_range[0]
        if($SESSION->dst_range[0] == 1971) {
            return 0;
        }
        calculate_user_dst_table($SESSION->dst_range[0] - 5, NULL);
        return dst_offset_on($time);
    }
    else {
        // We need a year larger than $SESSION->dst_range[1]
        if($SESSION->dst_range[1] == 2035) {
            return 0;
        }
        calculate_user_dst_table(NULL, $SESSION->dst_range[1] + 5);
        return dst_offset_on($time);
    }
}

function find_day_in_month($startday, $weekday, $month, $year) {

    $daysinmonth = days_in_month($month, $year);

    if($weekday == -1) {
        // Don't care about weekday, so return:
        //    abs($startday) if $startday != -1
        //    $daysinmonth otherwise
        return ($startday == -1) ? $daysinmonth : abs($startday);
    }

    // From now on we 're looking for a specific weekday

    // Give "end of month" its actual value, since we know it
    if($startday == -1) {
        $startday = -1 * $daysinmonth;
    }

    // Starting from day $startday, the sign is the direction

    if($startday < 1) {

        $startday = abs($startday);
        $lastmonthweekday  = strftime('%w', mktime(12, 0, 0, $month, $daysinmonth, $year, 0));

        // This is the last such weekday of the month
        $lastinmonth = $daysinmonth + $weekday - $lastmonthweekday;
        if($lastinmonth > $daysinmonth) {
            $lastinmonth -= 7;
        }

        // Find the first such weekday <= $startday
        while($lastinmonth > $startday) {
            $lastinmonth -= 7;
        }

        return $lastinmonth;

    }
    else {

        $indexweekday = strftime('%w', mktime(12, 0, 0, $month, $startday, $year, 0));

        $diff = $weekday - $indexweekday;
        if($diff < 0) {
            $diff += 7;
        }

        // This is the first such weekday of the month equal to or after $startday
        $firstfromindex = $startday + $diff;

        return $firstfromindex;

    }
}

/**
 * Calculate the number of days in a given month
 *
 * @param int $month The month whose day count is sought
 * @param int $year The year of the month whose day count is sought
 * @return int
 */
function days_in_month($month, $year) {
   return intval(date('t', mktime(12, 0, 0, $month, 1, $year, 0)));
}

/**
 * Calculate the position in the week of a specific calendar day
 *
 * @param int $day The day of the date whose position in the week is sought
 * @param int $month The month of the date whose position in the week is sought
 * @param int $year The year of the date whose position in the week is sought
 * @return int
 */
function dayofweek($day, $month, $year) {
    // I wonder if this is any different from
    // strftime('%w', mktime(12, 0, 0, $month, $daysinmonth, $year, 0));
    return intval(date('w', mktime(12, 0, 0, $month, $day, $year, 0)));
}

/// USER AUTHENTICATION AND LOGIN ////////////////////////////////////////

/**
 * Makes sure that $USER->sesskey exists, if $USER itself exists. It sets a new sesskey
 * if one does not already exist, but does not overwrite existing sesskeys. Returns the
 * sesskey string if $USER exists, or boolean false if not.
 *
 * @uses $USER
 * @return string
 */
function sesskey() {
    global $USER;

    if(!isset($USER)) {
        return false;
    }

    if (empty($USER->sesskey)) {
        $USER->sesskey = random_string(10);
    }

    return $USER->sesskey;
}


/**
 * For security purposes, this function will check that the currently
 * given sesskey (passed as a parameter to the script or this function)
 * matches that of the current user.
 *
 * @param string $sesskey optionally provided sesskey
 * @return bool
 */
function confirm_sesskey($sesskey=NULL) {
    global $USER;

    if (!empty($USER->ignoresesskey) || !empty($CFG->ignoresesskey)) {
        return true;
    }

    if (empty($sesskey)) {
        $sesskey = required_param('sesskey', PARAM_RAW);  // Check script parameters
    }

    if (!isset($USER->sesskey)) {
        return false;
    }

    return ($USER->sesskey === $sesskey);
}

/**
 * Setup all global $CFG course variables, set locale and also themes
 * This function can be used on pages that do not require login instead of require_login()
 *
 * @param mixed $courseorid id of the course or course object
 */
function course_setup($courseorid=0) {
    global $COURSE, $CFG, $SITE;

/// Redefine global $COURSE if needed
    if (empty($courseorid)) {
        // no change in global $COURSE - for backwards compatibiltiy
        // if require_rogin() used after require_login($courseid);
    } else if (is_object($courseorid)) {
        $COURSE = clone($courseorid);
    } else {
        global $course; // used here only to prevent repeated fetching from DB - may be removed later
        if (!empty($course->id) and $course->id == SITEID) {
            $COURSE = clone($SITE);
        } else if (!empty($course->id) and $course->id == $courseorid) {
            $COURSE = clone($course);
        } else {
            if (!$COURSE = get_record('course', 'id', $courseorid)) {
                error('Invalid course ID');
            }
        }
    }

/// set locale and themes
    moodle_setlocale();
    theme_setup();

}

/**
 * This function checks that the current user is logged in and has the
 * required privileges
 *
 * This function checks that the current user is logged in, and optionally
 * whether they are allowed to be in a particular course and view a particular
 * course module.
 * If they are not logged in, then it redirects them to the site login unless
 * $autologinguest is set and {@link $CFG}->autologinguests is set to 1 in which
 * case they are automatically logged in as guests.
 * If $courseid is given and the user is not enrolled in that course then the
 * user is redirected to the course enrolment page.
 * If $cm is given and the coursemodule is hidden and the user is not a teacher
 * in the course then the user is redirected to the course home page.
 *
 * @uses $CFG
 * @uses $SESSION
 * @uses $USER
 * @uses $FULLME
 * @uses SITEID
 * @uses $COURSE
 * @param mixed $courseorid id of the course or course object
 * @param bool $autologinguest
 * @param object $cm course module object
 */
function require_login($courseorid=0, $autologinguest=true, $cm=null) {

    global $CFG, $SESSION, $USER, $COURSE, $FULLME;

/// setup global $COURSE, themes, language and locale
    course_setup($courseorid);

/// If the user is not even logged in yet then make sure they are
    if (!isloggedin()) {
        //NOTE: $USER->site check was obsoleted by session test cookie,
        //      $USER->confirmed test is in login/index.php
        $SESSION->wantsurl = $FULLME;
        if (!empty($_SERVER['HTTP_REFERER'])) {
            $SESSION->fromurl  = $_SERVER['HTTP_REFERER'];
        }
        if ($autologinguest and !empty($CFG->guestloginbutton) and !empty($CFG->autologinguests) and ($COURSE->id == SITEID or $COURSE->guest) ) {
            $loginguest = '?loginguest=true';
        } else {
            $loginguest = '';
        }
        if (empty($CFG->loginhttps) or $loginguest) { //do not require https for guest logins
            redirect($CFG->wwwroot .'/login/index.php'. $loginguest);
        } else {
            $wwwroot = str_replace('http:','https:', $CFG->wwwroot);
            redirect($wwwroot .'/login/index.php');
        }
        exit;
    }

/// loginas as redirection if needed
    if ($COURSE->id != SITEID and !empty($USER->realuser)) {
        if ($USER->loginascontext->contextlevel == CONTEXT_COURSE) {
            if ($USER->loginascontext->instanceid != $COURSE->id) {
                print_error('loginasonecourse', '', $CFG->wwwroot.'/course/view.php?id='.$USER->loginascontext->instanceid);
            }
        }
    }


/// check whether the user should be changing password (but only if it is REALLY them)
    $userauth = get_auth_plugin($USER->auth);
    if (get_user_preferences('auth_forcepasswordchange') && empty($USER->realuser)) {
        if ($userauth->can_change_password()) {
            $SESSION->wantsurl = $FULLME;
            if ($userauth->change_password_url()) {
                //use plugin custom url
                redirect($userauth->change_password_url());
            } else {
                //use moodle internal method
                if (empty($CFG->loginhttps)) {
                    redirect($CFG->wwwroot .'/login/change_password.php');
                } else {
                    $wwwroot = str_replace('http:','https:', $CFG->wwwroot);
                    redirect($wwwroot .'/login/change_password.php');
                }
            }
        } else {
            error(get_string('nopasswordchangeforced', 'auth'));
        }
    }

/// Check that the user account is properly set up
    if (user_not_fully_set_up($USER)) {
        $SESSION->wantsurl = $FULLME;
        redirect($CFG->wwwroot .'/user/edit.php?id='. $USER->id .'&amp;course='. SITEID);
    }

/// Make sure current IP matches the one for this session (if required)
    if (!empty($CFG->tracksessionip)) {
        if ($USER->sessionIP != md5(getremoteaddr())) {
            error(get_string('sessionipnomatch', 'error'));
        }
    }

/// Make sure the USER has a sesskey set up.  Used for checking script parameters.
    sesskey();

    // Check that the user has agreed to a site policy if there is one
    if (!empty($CFG->sitepolicy)) {
        if (!$USER->policyagreed) {
            $SESSION->wantsurl = $FULLME;
            redirect($CFG->wwwroot .'/user/policy.php');
        }
    }

/// If the site is currently under maintenance, then print a message
    if (!has_capability('moodle/site:config',get_context_instance(CONTEXT_SYSTEM, SITEID))) {
        if (file_exists($CFG->dataroot.'/'.SITEID.'/maintenance.html')) {
            print_maintenance_message();
            exit;
        }
    }


    if ($COURSE->id == SITEID) {
/// We can eliminate hidden site activities straight away
        if (!empty($cm) && !$cm->visible and !has_capability('moodle/course:viewhiddenactivities',
                                                      get_context_instance(CONTEXT_COURSE, $COURSE->id))) {
            redirect($CFG->wwwroot, get_string('activityiscurrentlyhidden'));
        }
        return;

    } else {
/// Check if the user can be in a particular course
        if (!$context = get_context_instance(CONTEXT_COURSE, $COURSE->id)) {
            print_error('nocontext');
        }

        if (empty($USER->switchrole[$context->id]) &&
            !($COURSE->visible && course_parent_visible($COURSE)) &&
               !has_capability('moodle/course:viewhiddencourses', get_context_instance(CONTEXT_COURSE, $COURSE->id)) ){
            print_header_simple();
            notice(get_string('coursehidden'), $CFG->wwwroot .'/');
        }

    /// Non-guests who don't currently have access, check if they can be allowed in as a guest

        if ($USER->username != 'guest' and !has_capability('moodle/course:view', $context)) {
            if ($COURSE->guest == 1) {
                 // Temporarily assign them guest role for this context, if it fails later user is asked to enrol
                 has_capability('clearcache');   // Must clear cache
                 $guestcaps = get_role_context_caps($CFG->guestroleid, $context);
                 $USER->capabilities = merge_role_caps($USER->capabilities, $guestcaps);
            }
        }

    /// If the user is a guest then treat them according to the course policy about guests

        if (has_capability('moodle/legacy:guest', $context, NULL, false)) {
            switch ($COURSE->guest) {    /// Check course policy about guest access

                case 1:    /// Guests always allowed
                    if (!has_capability('moodle/course:view', $context)) {    // Prohibited by capability
                        print_header_simple();
                        notice(get_string('guestsnotallowed', '', format_string($COURSE->fullname)), "$CFG->wwwroot/login/index.php");
                    }
                    if (!empty($cm) and !$cm->visible) { // Not allowed to see module, send to course page
                        redirect($CFG->wwwroot.'/course/view.php?id='.$cm->course,
                                 get_string('activityiscurrentlyhidden'));
                    }

                    return;   // User is allowed to see this course

                    break;

                case 2:    /// Guests allowed with key
                    if (!empty($USER->enrolkey[$COURSE->id])) {   // Set by enrol/manual/enrol.php
                        return true;
                    }
                    //  otherwise drop through to logic below (--> enrol.php)
                    break;

                default:    /// Guests not allowed
                    print_header_simple('', '', get_string('loggedinasguest'));
                    if (empty($USER->switchrole[$context->id])) {  // Normal guest
                        notice(get_string('guestsnotallowed', '', format_string($COURSE->fullname)), "$CFG->wwwroot/login/index.php");
                    } else {
                        notify(get_string('guestsnotallowed', '', format_string($COURSE->fullname)));
                        echo '<div class="notifyproblem">'.switchroles_form($COURSE->id).'</div>';
                        print_footer($COURSE);
                        exit;
                    }
                    break;
            }

    /// For non-guests, check if they have course view access

        } else if (has_capability('moodle/course:view', $context)) {
            if (!empty($USER->realuser)) {   // Make sure the REAL person can also access this course
                if (!has_capability('moodle/course:view', $context, $USER->realuser)) {
                    print_header_simple();
                    notice(get_string('studentnotallowed', '', fullname($USER, true)), $CFG->wwwroot .'/');
                }
            }

        /// Make sure they can read this activity too, if specified

            if (!empty($cm) and !$cm->visible and !has_capability('moodle/course:viewhiddenactivities', $context)) {
                redirect($CFG->wwwroot.'/course/view.php?id='.$cm->course, get_string('activityiscurrentlyhidden'));
            }
            return;   // User is allowed to see this course

        }


    /// Currently not enrolled in the course, so see if they want to enrol
        $SESSION->wantsurl = $FULLME;
        redirect($CFG->wwwroot .'/course/enrol.php?id='. $COURSE->id);
        die;
    }
}



/**
 * This function just makes sure a user is logged out.
 *
 * @uses $CFG
 * @uses $USER
 */
function require_logout() {

    global $USER, $CFG, $SESSION;

    if (isloggedin()) {
        add_to_log(SITEID, "user", "logout", "view.php?id=$USER->id&course=".SITEID, $USER->id, 0, $USER->id);

        $authsequence = get_enabled_auth_plugins(); // auths, in sequence
        foreach($authsequence as $authname) {
            $authplugin = get_auth_plugin($authname);
            $authplugin->prelogout_hook();
        }
    }

    if (ini_get_bool("register_globals") and check_php_version("4.3.0")) {
        // This method is just to try to avoid silly warnings from PHP 4.3.0
        session_unregister("USER");
        session_unregister("SESSION");
    }

    // Initialize variable to pass-by-reference to headers_sent(&$file, &$line)
    $file = $line = null;
    if (headers_sent($file, $line)) {
        error_log('MoodleSessionTest cookie could not be set in moodlelib.php:'.__LINE__);
        error_log('Headers were already sent in file: '.$file.' on line '.$line);
    } else {
        setcookie('MoodleSessionTest'.$CFG->sessioncookie, '', time() - 3600, $CFG->sessioncookiepath);
    }

    unset($_SESSION['USER']);
    unset($_SESSION['SESSION']);

    unset($SESSION);
    unset($USER);

}

/**
 * This is a weaker version of {@link require_login()} which only requires login
 * when called from within a course rather than the site page, unless
 * the forcelogin option is turned on.
 *
 * @uses $CFG
 * @param mixed $courseorid The course object or id in question
 * @param bool $autologinguest Allow autologin guests if that is wanted
 * @param object $cm Course activity module if known
 */
function require_course_login($courseorid, $autologinguest=true, $cm=null) {
    global $CFG;
    if (!empty($CFG->forcelogin)) {
        // login required for both SITE and courses
        require_login($courseorid, $autologinguest, $cm);

    } else if (!empty($cm) and !$cm->visible) {
        // always login for hidden activities
        require_login($courseorid, $autologinguest, $cm);

    } else if ((is_object($courseorid) and $courseorid->id == SITEID)
          or (!is_object($courseorid) and $courseorid == SITEID)) {
        //login for SITE not required
        return;

    } else {
        // course login always required
        require_login($courseorid, $autologinguest, $cm);
    }
}

/**
 * Modify the user table by setting the currently logged in user's
 * last login to now.
 *
 * @uses $USER
 * @return bool
 */
function update_user_login_times() {
    global $USER;

    $user = new object();
    $USER->lastlogin = $user->lastlogin = $USER->currentlogin;
    $USER->currentlogin = $user->lastaccess = $user->currentlogin = time();

    $user->id = $USER->id;

    return update_record('user', $user);
}

/**
 * Determines if a user has completed setting up their account.
 *
 * @param user $user A {@link $USER} object to test for the existance of a valid name and email
 * @return bool
 */
function user_not_fully_set_up($user) {
    return ($user->username != 'guest' and (empty($user->firstname) or empty($user->lastname) or empty($user->email) or over_bounce_threshold($user)));
}

function over_bounce_threshold($user) {

    global $CFG;

    if (empty($CFG->handlebounces)) {
        return false;
    }
    // set sensible defaults
    if (empty($CFG->minbounces)) {
        $CFG->minbounces = 10;
    }
    if (empty($CFG->bounceratio)) {
        $CFG->bounceratio = .20;
    }
    $bouncecount = 0;
    $sendcount = 0;
    if ($bounce = get_record('user_preferences','userid',$user->id,'name','email_bounce_count')) {
        $bouncecount = $bounce->value;
    }
    if ($send = get_record('user_preferences','userid',$user->id,'name','email_send_count')) {
        $sendcount = $send->value;
    }
    return ($bouncecount >= $CFG->minbounces && $bouncecount/$sendcount >= $CFG->bounceratio);
}

/**
 * @param $user - object containing an id
 * @param $reset - will reset the count to 0
 */
function set_send_count($user,$reset=false) {
    if ($pref = get_record('user_preferences','userid',$user->id,'name','email_send_count')) {
        $pref->value = (!empty($reset)) ? 0 : $pref->value+1;
        update_record('user_preferences',$pref);
    }
    else if (!empty($reset)) { // if it's not there and we're resetting, don't bother.
        // make a new one
        $pref->name = 'email_send_count';
        $pref->value = 1;
        $pref->userid = $user->id;
        insert_record('user_preferences',$pref, false);
    }
}

/**
* @param $user - object containing an id
 * @param $reset - will reset the count to 0
 */
function set_bounce_count($user,$reset=false) {
    if ($pref = get_record('user_preferences','userid',$user->id,'name','email_bounce_count')) {
        $pref->value = (!empty($reset)) ? 0 : $pref->value+1;
        update_record('user_preferences',$pref);
    }
    else if (!empty($reset)) { // if it's not there and we're resetting, don't bother.
        // make a new one
        $pref->name = 'email_bounce_count';
        $pref->value = 1;
        $pref->userid = $user->id;
        insert_record('user_preferences',$pref, false);
    }
}

/**
 * Keeps track of login attempts
 *
 * @uses $SESSION
 */
function update_login_count() {

    global $SESSION;

    $max_logins = 10;

    if (empty($SESSION->logincount)) {
        $SESSION->logincount = 1;
    } else {
        $SESSION->logincount++;
    }

    if ($SESSION->logincount > $max_logins) {
        unset($SESSION->wantsurl);
        error(get_string('errortoomanylogins'));
    }
}

/**
 * Resets login attempts
 *
 * @uses $SESSION
 */
function reset_login_count() {
    global $SESSION;

    $SESSION->logincount = 0;
}

function sync_metacourses() {

    global $CFG;

    if (!$courses = get_records('course', 'metacourse', 1)) {
        return;
    }

    foreach ($courses as $course) {
        sync_metacourse($course);
    }
}

/**
 * Goes through all enrolment records for the courses inside the metacourse and sync with them.
 *
 * @param mixed $course the metacourse to synch. Either the course object itself, or the courseid.
 */
function sync_metacourse($course) {
    global $CFG;

    // Check the course is valid.
    if (!is_object($course)) {
        if (!$course = get_record('course', 'id', $course)) {
            return false; // invalid course id
        }
    }

    // Check that we actually have a metacourse.
    if (empty($course->metacourse)) {
        return false;
    }

    // Get a list of roles that should not be synced.
    if (!empty($CFG->nonmetacoursesyncroleids)) {
        $roleexclusions = 'ra.roleid NOT IN (' . $CFG->nonmetacoursesyncroleids . ') AND';
    } else {
        $roleexclusions = '';
    }

    // Get the context of the metacourse.
    $context = get_context_instance(CONTEXT_COURSE, $course->id); // SITEID can not be a metacourse

    // We do not ever want to unassign the list of metacourse manager, so get a list of them.
    if ($users = get_users_by_capability($context, 'moodle/course:managemetacourse')) {
        $managers = array_keys($users);
    } else {
        $managers = array();
    }

    // Get assignments of a user to a role that exist in a child course, but
    // not in the meta coure. That is, get a list of the assignments that need to be made.
    if (!$assignments = get_records_sql("
            SELECT
                ra.id, ra.roleid, ra.userid
            FROM
                {$CFG->prefix}role_assignments ra,
                {$CFG->prefix}context con,
                {$CFG->prefix}course_meta cm
            WHERE
                ra.contextid = con.id AND
                con.contextlevel = " . CONTEXT_COURSE . " AND
                con.instanceid = cm.child_course AND
                cm.parent_course = {$course->id} AND
                $roleexclusions
                NOT EXISTS (
                    SELECT 1 FROM
                        {$CFG->prefix}role_assignments ra2
                    WHERE
                        ra2.userid = ra.userid AND
                        ra2.roleid = ra.roleid AND
                        ra2.contextid = {$context->id}
                )
    ")) {
        $assignments = array();
    }

    // Get assignments of a user to a role that exist in the meta course, but
    // not in any child courses. That is, get a list of the unassignments that need to be made.
    if (!$unassignments = get_records_sql("
            SELECT
                ra.id, ra.roleid, ra.userid
            FROM
                {$CFG->prefix}role_assignments ra
            WHERE
                ra.contextid = {$context->id} AND
                $roleexclusions
                NOT EXISTS (
                    SELECT 1 FROM
                        {$CFG->prefix}role_assignments ra2,
                        {$CFG->prefix}context con2,
                        {$CFG->prefix}course_meta cm
                    WHERE
                        ra2.userid = ra.userid AND
                        ra2.roleid = ra.roleid AND
                        ra2.contextid = con2.id AND
                        con2.contextlevel = " . CONTEXT_COURSE . " AND
                        con2.instanceid = cm.child_course AND
                        cm.parent_course = {$course->id}
                )
    ")) {
        $unassignments = array();
    }

    $success = true;

    // Make the unassignments, if they are not managers.
    foreach ($unassignments as $unassignment) {
        if (!in_array($unassignment->userid, $managers)) {
            $success = role_unassign($unassignment->roleid, $unassignment->userid, 0, $context->id) && $success;
        }
    }

    // Make the assignments.
    foreach ($assignments as $assignment) {
        $success = role_assign($assignment->roleid, $assignment->userid, 0, $context->id) && $success;
    }

    return $success;

// TODO: finish timeend and timestart
// maybe we could rely on cron job to do the cleaning from time to time
}

/**
 * Adds a record to the metacourse table and calls sync_metacoures
 */
function add_to_metacourse ($metacourseid, $courseid) {

    if (!$metacourse = get_record("course","id",$metacourseid)) {
        return false;
    }

    if (!$course = get_record("course","id",$courseid)) {
        return false;
    }

    if (!$record = get_record("course_meta","parent_course",$metacourseid,"child_course",$courseid)) {
        $rec = new object();
        $rec->parent_course = $metacourseid;
        $rec->child_course = $courseid;
        if (!insert_record('course_meta',$rec)) {
            return false;
        }
        return sync_metacourse($metacourseid);
    }
    return true;

}

/**
 * Removes the record from the metacourse table and calls sync_metacourse
 */
function remove_from_metacourse($metacourseid, $courseid) {

    if (delete_records('course_meta','parent_course',$metacourseid,'child_course',$courseid)) {
        return sync_metacourse($metacourseid);
    }
    return false;
}


/**
 * Determines if a user is currently logged in
 *
 * @uses $USER
 * @return bool
 */
function isloggedin() {
    global $USER;

    return (!empty($USER->id));
}

/**
 * Determines if a user is logged in as real guest user with username 'guest'.
 * This function is similar to original isguest() in 1.6 and earlier.
 * Current isguest() is deprecated - do not use it anymore.
 *
 * @param $user mixed user object or id, $USER if not specified
 * @return bool true if user is the real guest user, false if not logged in or other user
 */
function isguestuser($user=NULL) {
    global $USER;
    if ($user === NULL) {
        $user = $USER;
    } else if (is_numeric($user)) {
        $user = get_record('user', 'id', $user, '', '', '', '', 'id, username');
    }

    if (empty($user->id)) {
        return false; // not logged in, can not be guest
    }

    return ($user->username == 'guest');
}

/**
 * Determines if the currently logged in user is in editing mode.
 * Note: originally this function had $userid parameter - it was not usable anyway
 *
 * @uses $USER
 * @param int $courseid The id of the course being tested
 * @return bool
 */
function isediting($courseid) {
    global $USER;

    if (empty($USER->editing)) {
        return false;

    } else {
        return editcourseallowed($courseid);
    }
}

/**
 * Verifies if user allowed to edit something in the course page.
 * @param int $courseid The id of the course being tested
 * @return bool
 */
function editcourseallowed($courseid) {
    global $USER;

    // cache the result per course, it is automatically reset when using switchrole or loginas
    if (!array_key_exists('courseeditallowed', $USER)) {
        $USER->courseeditallowed = array();
    }

    if (!array_key_exists($courseid, $USER->courseeditallowed)) {
        $USER->courseeditallowed[$courseid] = has_capability_including_child_contexts(get_context_instance(CONTEXT_COURSE, $courseid),
                                            array('moodle/site:manageblocks', 'moodle/course:manageactivities'));
    }

    return $USER->courseeditallowed[$courseid];
}

/**
 * Determines if the logged in user is currently moving an activity
 *
 * @uses $USER
 * @param int $courseid The id of the course being tested
 * @return bool
 */
function ismoving($courseid) {
    global $USER;

    if (!empty($USER->activitycopy)) {
        return ($USER->activitycopycourse == $courseid);
    }
    return false;
}

/**
 * Given an object containing firstname and lastname
 * values, this function returns a string with the
 * full name of the person.
 * The result may depend on system settings
 * or language.  'override' will force both names
 * to be used even if system settings specify one.
 *
 * @uses $CFG
 * @uses $SESSION
 * @param object $user A {@link $USER} object to get full name of
 * @param bool $override If true then the name will be first name followed by last name rather than adhering to fullnamedisplay setting.
 */
function fullname($user, $override=false) {

    global $CFG, $SESSION;

    if (!isset($user->firstname) and !isset($user->lastname)) {
        return '';
    }

    if (!$override) {
        if (!empty($CFG->forcefirstname)) {
            $user->firstname = $CFG->forcefirstname;
        }
        if (!empty($CFG->forcelastname)) {
            $user->lastname = $CFG->forcelastname;
        }
    }

    if (!empty($SESSION->fullnamedisplay)) {
        $CFG->fullnamedisplay = $SESSION->fullnamedisplay;
    }

    if ($CFG->fullnamedisplay == 'firstname lastname') {
        return $user->firstname .' '. $user->lastname;

    } else if ($CFG->fullnamedisplay == 'lastname firstname') {
        return $user->lastname .' '. $user->firstname;

    } else if ($CFG->fullnamedisplay == 'firstname') {
        if ($override) {
            return get_string('fullnamedisplay', '', $user);
        } else {
            return $user->firstname;
        }
    }

    return get_string('fullnamedisplay', '', $user);
}

/**
 * Sets a moodle cookie with an encrypted string
 *
 * @uses $CFG
 * @uses DAYSECS
 * @uses HOURSECS
 * @param string $thing The string to encrypt and place in a cookie
 */
function set_moodle_cookie($thing) {
    global $CFG;

    if ($thing == 'guest') {  // Ignore guest account
        return;
    }

    $cookiename = 'MOODLEID_'.$CFG->sessioncookie;

    $days = 60;
    $seconds = DAYSECS*$days;

    setCookie($cookiename, '', time() - HOURSECS, '/');
    setCookie($cookiename, rc4encrypt($thing), time()+$seconds, '/');
}

/**
 * Gets a moodle cookie with an encrypted string
 *
 * @uses $CFG
 * @return string
 */
function get_moodle_cookie() {
    global $CFG;

    $cookiename = 'MOODLEID_'.$CFG->sessioncookie;

    if (empty($_COOKIE[$cookiename])) {
        return '';
    } else {
        $thing = rc4decrypt($_COOKIE[$cookiename]);
        return ($thing == 'guest') ? '': $thing;  // Ignore guest account
    }
}

/**
 * Returns whether a given authentication plugin exists.
 *
 * @uses $CFG
 * @param string $auth Form of authentication to check for. Defaults to the
 *        global setting in {@link $CFG}.
 * @return boolean Whether the plugin is available.
 */
function exists_auth_plugin($auth) {
    global $CFG;

    if (file_exists("{$CFG->dirroot}/auth/$auth/auth.php")) {
        return is_readable("{$CFG->dirroot}/auth/$auth/auth.php");
    }
    return false;
}

/**
 * Checks if a given plugin is in the list of enabled authentication plugins.
 *
 * @param string $auth Authentication plugin.
 * @return boolean Whether the plugin is enabled.
 */
function is_enabled_auth($auth) {
    if (empty($auth)) {
        return false;
    }

    $enabled = get_enabled_auth_plugins();

    return in_array($auth, $enabled);
}

/**
 * Returns an authentication plugin instance.
 *
 * @uses $CFG
 * @param string $auth name of authentication plugin
 * @return object An instance of the required authentication plugin.
 */
function get_auth_plugin($auth) {
    global $CFG;

    // check the plugin exists first
    if (! exists_auth_plugin($auth)) {
        error("Authentication plugin '$auth' not found.");
    }

    // return auth plugin instance
    require_once "{$CFG->dirroot}/auth/$auth/auth.php";
    $class = "auth_plugin_$auth";
    return new $class;
}

/**
 * Returns array of active auth plugins.
 *
 * @param bool $fix fix $CFG->auth if needed
 * @return array
 */
function get_enabled_auth_plugins($fix=false) {
    global $CFG;

    $default = array('manual', 'nologin');

    if (empty($CFG->auth)) {
        $auths = array();
    } else {
        $auths = explode(',', $CFG->auth);
    }

    if ($fix) {
        $auths = array_unique($auths);
        foreach($auths as $k=>$authname) {
            if (!exists_auth_plugin($authname) or in_array($authname, $default)) {
                unset($auths[$k]);
            }
        }
        $newconfig = implode(',', $auths);
        if (!isset($CFG->auth) or $newconfig != $CFG->auth) {
            set_config('auth', $newconfig);
        }
    }

    return (array_merge($default, $auths));
}

/**
 * Returns true if an internal authentication method is being used.
 * if method not specified then, global default is assumed
 *
 * @uses $CFG
 * @param string $auth Form of authentication required
 * @return bool
 */
function is_internal_auth($auth) {
    $authplugin = get_auth_plugin($auth); // throws error if bad $auth
    return $authplugin->is_internal();
}

/**
 * Returns an array of user fields
 *
 * @uses $CFG
 * @uses $db
 * @return array User field/column names
 */
function get_user_fieldnames() {

    global $CFG, $db;

    $fieldarray = $db->MetaColumnNames($CFG->prefix.'user');
    unset($fieldarray['ID']);

    return $fieldarray;
}

/**
 * Creates the default "guest" user. Used both from
 * admin/index.php and login/index.php
 * @return mixed user object created or boolean false if the creation has failed
 */
function create_guest_record() {

    global $CFG;

    $guest->auth        = 'manual';
    $guest->username    = 'guest';
    $guest->password    = hash_internal_user_password('guest');
    $guest->firstname   = addslashes(get_string('guestuser'));
    $guest->lastname    = ' ';
    $guest->email       = 'root@localhost';
    $guest->description = addslashes(get_string('guestuserinfo'));
    $guest->mnethostid  = $CFG->mnet_localhost_id;
    $guest->confirmed   = 1;
    $guest->lang        = $CFG->lang;
    $guest->timemodified= time();

    if (! $guest->id = insert_record("user", $guest)) {
        return false;
    }

    return $guest;
}

/**
 * Creates a bare-bones user record
 *
 * @uses $CFG
 * @param string $username New user's username to add to record
 * @param string $password New user's password to add to record
 * @param string $auth Form of authentication required
 * @return object A {@link $USER} object
 * @todo Outline auth types and provide code example
 */
function create_user_record($username, $password, $auth='manual') {
    global $CFG;

    //just in case check text case
    $username = trim(moodle_strtolower($username));

    $authplugin = get_auth_plugin($auth);

    if ($newinfo = $authplugin->get_userinfo($username)) {
        $newinfo = truncate_userinfo($newinfo);
        foreach ($newinfo as $key => $value){
            $newuser->$key = addslashes($value);
        }
    }

    if (!empty($newuser->email)) {
        if (email_is_not_allowed($newuser->email)) {
            unset($newuser->email);
        }
    }

    $newuser->auth = $auth;
    $newuser->username = $username;

    // fix for MDL-8480
    // user CFG lang for user if $newuser->lang is empty
    // or $user->lang is not an installed language
    $sitelangs = array_keys(get_list_of_languages());
    if (empty($newuser->lang) || !in_array($newuser->lang, $sitelangs)) {
        $newuser -> lang = $CFG->lang;
    }
    $newuser->confirmed = 1;
    $newuser->lastip = getremoteaddr();
    $newuser->timemodified = time();
    $newuser->mnethostid = $CFG->mnet_localhost_id;

    if (insert_record('user', $newuser)) {
        $user = get_complete_user_data('username', $newuser->username);
        if(!empty($CFG->{'auth_'.$newuser->auth.'_forcechangepassword'})){
            set_user_preference('auth_forcepasswordchange', 1, $user->id);
        }
        update_internal_user_password($user, $password);
        return $user;
    }
    return false;
}

/**
 * Will update a local user record from an external source
 *
 * @uses $CFG
 * @param string $username New user's username to add to record
 * @return user A {@link $USER} object
 */
function update_user_record($username, $authplugin) {
    $username = trim(moodle_strtolower($username)); /// just in case check text case

    $oldinfo = get_record('user', 'username', $username, '','','','', 'username, auth');
    $userauth = get_auth_plugin($oldinfo->auth);

    if ($newinfo = $userauth->get_userinfo($username)) {
        $newinfo = truncate_userinfo($newinfo);
        foreach ($newinfo as $key => $value){
            $confkey = 'field_updatelocal_' . $key;
            if (!empty($userauth->config->$confkey) and $userauth->config->$confkey === 'onlogin') {
                $value = addslashes(stripslashes($value));   // Just in case
                set_field('user', $key, $value, 'username', $username)
                    or error_log("Error updating $key for $username");
            }
        }
    }

    return get_complete_user_data('username', $username);
}

function truncate_userinfo($info) {
/// will truncate userinfo as it comes from auth_get_userinfo (from external auth)
/// which may have large fields

    // define the limits
    $limit = array(
                    'username'    => 100,
                    'idnumber'    =>  64,
                    'firstname'   => 100,
                    'lastname'    => 100,
                    'email'       => 100,
                    'icq'         =>  15,
                    'phone1'      =>  20,
                    'phone2'      =>  20,
                    'institution' =>  40,
                    'department'  =>  30,
                    'address'     =>  70,
                    'city'        =>  20,
                    'country'     =>   2,
                    'url'         => 255,
                    );

    // apply where needed
    foreach (array_keys($info) as $key) {
        if (!empty($limit[$key])) {
            $info[$key] = trim(substr($info[$key],0, $limit[$key]));
        }
    }

    return $info;
}

/**
 * Retrieve the guest user object
 *
 * @uses $CFG
 * @return user A {@link $USER} object
 */
function guest_user() {
    global $CFG;

    if ($newuser = get_record('user', 'username', 'guest', 'mnethostid',  $CFG->mnet_localhost_id)) {
        $newuser->confirmed = 1;
        $newuser->lang = $CFG->lang;
        $newuser->lastip = getremoteaddr();
    }

    return $newuser;
}

/**
 * Given a username and password, this function looks them
 * up using the currently selected authentication mechanism,
 * and if the authentication is successful, it returns a
 * valid $user object from the 'user' table.
 *
 * Uses auth_ functions from the currently active auth module
 *
 * @uses $CFG
 * @param string $username  User's username (with system magic quotes)
 * @param string $password  User's password (with system magic quotes)
 * @return user|flase A {@link $USER} object or false if error
 */
function authenticate_user_login($username, $password) {

    global $CFG;

    $authsenabled = get_enabled_auth_plugins();

    if ($user = get_complete_user_data('username', $username)) {
        $auth = empty($user->auth) ? 'manual' : $user->auth;  // use manual if auth not set
        if ($auth=='nologin' or !is_enabled_auth($auth)) {
            add_to_log(0, 'login', 'error', 'index.php', $username);
            error_log('[client '.$_SERVER['REMOTE_ADDR']."]  $CFG->wwwroot  Disabled Login:  $username  ".$_SERVER['HTTP_USER_AGENT']);
            return false;
        }
        if (!empty($user->deleted)) {
            add_to_log(0, 'login', 'error', 'index.php', $username);
            error_log('[client '.$_SERVER['REMOTE_ADDR']."]  $CFG->wwwroot  Deleted Login:  $username  ".$_SERVER['HTTP_USER_AGENT']);
            return false;
        }
        $auths = array($auth);

    } else {
        $auths = $authsenabled;
        $user = new object();
        $user->id = 0;     // User does not exist
    }

    foreach ($auths as $auth) {
        $authplugin = get_auth_plugin($auth);

        // on auth fail fall through to the next plugin
        if (!$authplugin->user_login($username, $password)) {
            continue;
        }

        // successful authentication
        if ($user->id) {                          // User already exists in database
            if (empty($user->auth)) {             // For some reason auth isn't set yet
                set_field('user', 'auth', $auth, 'username', $username);
                $user->auth = $auth;
            }

            update_internal_user_password($user, $password); // just in case salt or encoding were changed (magic quotes too one day)

            if (!$authplugin->is_internal()) {            // update user record from external DB
                $user = update_user_record($username, get_auth_plugin($user->auth));
            }
        } else {
            // if user not found, create him
            $user = create_user_record($username, $password, $auth);
        }

        $authplugin->sync_roles($user);

        foreach ($authsenabled as $hau) {
            $hauth = get_auth_plugin($hau);
            $hauth->user_authenticated_hook($user, $username, $password);
        }

    /// Log in to a second system if necessary
    /// NOTICE: /sso/ will be moved to auth and deprecated soon; use user_authenticated_hook() instead
        if (!empty($CFG->sso)) {
            include_once($CFG->dirroot .'/sso/'. $CFG->sso .'/lib.php');
            if (function_exists('sso_user_login')) {
                if (!sso_user_login($username, $password)) {   // Perform the signon process
                    notify('Second sign-on failed');
                }
            }
        }

        return $user;

    }

    // failed if all the plugins have failed
    add_to_log(0, 'login', 'error', 'index.php', $username);
    error_log('[client '.$_SERVER['REMOTE_ADDR']."]  $CFG->wwwroot  Failed Login:  $username  ".$_SERVER['HTTP_USER_AGENT']);
    return false;
}

/**
 * Compare password against hash stored in internal user table.
 * If necessary it also updates the stored hash to new format.
 *
 * @param object user
 * @param string plain text password
 * @return bool is password valid?
 */
function validate_internal_user_password(&$user, $password) {
    global $CFG;

    if (!isset($CFG->passwordsaltmain)) {
        $CFG->passwordsaltmain = '';
    }

    $validated = false;

	// get password original encoding in case it was not updated to unicode yet
    $textlib = textlib_get_instance();
    $convpassword = $textlib->convert($password, 'utf-8', get_string('oldcharset'));

    if ($user->password == md5($password.$CFG->passwordsaltmain) or $user->password == md5($password)
        or $user->password == md5($convpassword.$CFG->passwordsaltmain) or $user->password == md5($convpassword)) {
        $validated = true;
    } else {
        for ($i=1; $i<=20; $i++) { //20 alternative salts should be enough, right?
            $alt = 'passwordsaltalt'.$i;
            if (!empty($CFG->$alt)) {
                if ($user->password == md5($password.$CFG->$alt) or $user->password == md5($convpassword.$CFG->$alt)) {
                    $validated = true;
                    break;
                }
            }
        }
    }

    if ($validated) {
        // force update of password hash using latest main password salt and encoding if needed
        update_internal_user_password($user, $password);
    }

    return $validated;
}

/**
 * Calculate hashed value from password using current hash mechanism.
 *
 * @param string password
 * @return string password hash
 */
function hash_internal_user_password($password) {
    global $CFG;

    if (isset($CFG->passwordsaltmain)) {
        return md5($password.$CFG->passwordsaltmain);
    } else {
        return md5($password);
    }
}

/**
 * Update pssword hash in user object.
 *
 * @param object user
 * @param string plain text password
 * @param bool store changes also in db, default true
 * @return true if hash changed
 */
function update_internal_user_password(&$user, $password) {
    global $CFG;

    $authplugin = get_auth_plugin($user->auth);
    if (!empty($authplugin->config->preventpassindb)) {
        $hashedpassword = 'not cached';
    } else {
        $hashedpassword = hash_internal_user_password($password);
    }

    return set_field('user', 'password',  $hashedpassword, 'id', $user->id);
}

/**
 * Get a complete user record, which includes all the info
 * in the user record
 * Intended for setting as $USER session variable
 *
 * @uses $CFG
 * @uses SITEID
 * @param string $field The user field to be checked for a given value.
 * @param string $value The value to match for $field.
 * @return user A {@link $USER} object.
 */
function get_complete_user_data($field, $value, $mnethostid=null) {

    global $CFG;

    if (!$field || !$value) {
        return false;
    }

/// Build the WHERE clause for an SQL query

    $constraints = $field .' = \''. $value .'\' AND deleted <> \'1\'';

    if (is_null($mnethostid)) {
        // if null, we restrict to local users
        // ** testing for local user can be done with
        //    mnethostid = $CFG->mnet_localhost_id
        //    or with
        //    auth != 'mnet'
        //    but the first one is FAST with our indexes
        $mnethostid = $CFG->mnet_localhost_id;
    }
    $mnethostid = (int)$mnethostid;
    $constraints .= ' AND mnethostid = \''.$mnethostid.'\'';

/// Get all the basic user data

    if (! $user = get_record_select('user', $constraints)) {
        return false;
    }

/// Get various settings and preferences

    if ($displays = get_records('course_display', 'userid', $user->id)) {
        foreach ($displays as $display) {
            $user->display[$display->course] = $display->display;
        }
    }

    $user->preference = get_user_preferences(null, null, $user->id);

    if ($lastaccesses = get_records('user_lastaccess', 'userid', $user->id)) {
        foreach ($lastaccesses as $lastaccess) {
            $user->lastcourseaccess[$lastaccess->courseid] = $lastaccess->timeaccess;
        }
    }

    if ($groupids = groups_get_all_groups_for_user($user->id)) { //TODO:check.
        foreach ($groupids as $groupid) {
            $courseid = groups_get_course($groupid);
            //change this to 2D array so we can put multiple groups in a course
            $user->groupmember[$courseid][] = $groupid;
        }
    }

/// Rewrite some variables if necessary
    if (!empty($user->description)) {
        $user->description = true;   // No need to cart all of it around
    }
    if ($user->username == 'guest') {
        $user->lang       = $CFG->lang;               // Guest language always same as site
        $user->firstname  = get_string('guestuser');  // Name always in current language
        $user->lastname   = ' ';
    }

    $user->sesskey  = random_string(10);
    $user->sessionIP = md5(getremoteaddr());   // Store the current IP in the session

    return $user;
}



/*
 * When logging in, this function is run to set certain preferences
 * for the current SESSION
 */
function set_login_session_preferences() {
    global $SESSION, $CFG;

    $SESSION->justloggedin = true;

    unset($SESSION->lang);

    // Restore the calendar filters, if saved
    if (intval(get_user_preferences('calendar_persistflt', 0))) {
        include_once($CFG->dirroot.'/calendar/lib.php');
        calendar_set_filters_status(get_user_preferences('calendav_savedflt', 0xff));
    }
}


/**
 * Delete a course, including all related data from the database,
 * and any associated files from the moodledata folder.
 *
 * @param int $courseid The id of the course to delete.
 * @param bool $showfeedback Whether to display notifications of each action the function performs.
 * @return bool true if all the removals succeeded. false if there were any failures. If this
 *             method returns false, some of the removals will probably have succeeded, and others
 *             failed, but you have no way of knowing which.
 */
function delete_course($courseid, $showfeedback = true) {
    global $CFG;
    $result = true;

    if (!remove_course_contents($courseid, $showfeedback)) {
        if ($showfeedback) {
            notify("An error occurred while deleting some of the course contents.");
        }
        $result = false;
    }

    if (!delete_records("course", "id", $courseid)) {
        if ($showfeedback) {
            notify("An error occurred while deleting the main course record.");
        }
        $result = false;
    }

    if (!delete_records('context', 'contextlevel', CONTEXT_COURSE, 'instanceid', $courseid)) {
        if ($showfeedback) {
            notify("An error occurred while deleting the main context record.");
        }
        $result = false;
    }

    if (!fulldelete($CFG->dataroot.'/'.$courseid)) {
        if ($showfeedback) {
            notify("An error occurred while deleting the course files.");
        }
        $result = false;
    }

    return $result;
}

/**
 * Clear a course out completely, deleting all content
 * but don't delete the course itself
 *
 * @uses $CFG
 * @param int $courseid The id of the course that is being deleted
 * @param bool $showfeedback Whether to display notifications of each action the function performs.
 * @return bool true if all the removals succeeded. false if there were any failures. If this
 *             method returns false, some of the removals will probably have succeeded, and others
 *             failed, but you have no way of knowing which.
 */
function remove_course_contents($courseid, $showfeedback=true) {

    global $CFG;

    $result = true;

    if (! $course = get_record('course', 'id', $courseid)) {
        error('Course ID was incorrect (can\'t find it)');
    }

    $strdeleted = get_string('deleted');

/// First delete every instance of every module

    if ($allmods = get_records('modules') ) {
        foreach ($allmods as $mod) {
            $modname = $mod->name;
            $modfile = $CFG->dirroot .'/mod/'. $modname .'/lib.php';
            $moddelete = $modname .'_delete_instance';       // Delete everything connected to an instance
            $moddeletecourse = $modname .'_delete_course';   // Delete other stray stuff (uncommon)
            $count=0;
            if (file_exists($modfile)) {
                include_once($modfile);
                if (function_exists($moddelete)) {
                    if ($instances = get_records($modname, 'course', $course->id)) {
                        foreach ($instances as $instance) {
                            if ($cm = get_coursemodule_from_instance($modname, $instance->id, $course->id)) {
                                delete_context(CONTEXT_MODULE, $cm->id);
                            }
                            if ($moddelete($instance->id)) {
                                $count++;

                            } else {
                                notify('Could not delete '. $modname .' instance '. $instance->id .' ('. format_string($instance->name) .')');
                                $result = false;
                            }
                        }
                    }
                } else {
                    notify('Function '. $moddelete() .'doesn\'t exist!');
                    $result = false;
                }

                if (function_exists($moddeletecourse)) {
                    $moddeletecourse($course, $showfeedback);
                }
            }
            if ($showfeedback) {
                notify($strdeleted .' '. $count .' x '. $modname);
            }
        }
    } else {
        error('No modules are installed!');
    }

/// Give local code a chance to delete its references to this course.
    require_once('locallib.php');
    notify_local_delete_course($courseid, $showfeedback);

/// Delete course blocks

    if ($blocks = get_records_sql("SELECT *
                                   FROM {$CFG->prefix}block_instance
                                   WHERE pagetype = '".PAGE_COURSE_VIEW."'
                                   AND pageid = $course->id")) {
        if (delete_records('block_instance', 'pagetype', PAGE_COURSE_VIEW, 'pageid', $course->id)) {
            if ($showfeedback) {
                notify($strdeleted .' block_instance');
            }

            require_once($CFG->libdir.'/blocklib.php');
            foreach ($blocks as $block) {  /// Delete any associated contexts for this block

                // Block instances are rarely created. Since the block instance is gone from the above delete
                // statement, calling delete_context() will generate a warning as get_context_instance could
                // no longer create the context as the block is already gone.
                if (record_exists('context', 'contextlevel', CONTEXT_BLOCK, 'instanceid', $block->id)) {
                    delete_context(CONTEXT_BLOCK, $block->id);
                }

                // fix for MDL-7164
                // Get the block object and call instance_delete()
                if (!$record = blocks_get_record($block->blockid)) {
                    $result = false;
                    continue;
                }
                if (!$obj = block_instance($record->name, $block)) {
                    $result = false;
                    continue;
                }
                // Return value ignored, in core mods this does not do anything, but just in case
                // third party blocks might have stuff to clean up
                // we execute this anyway
                $obj->instance_delete();
            }
        } else {
            $result = false;
        }
    }

/// Delete any groups, removing members and grouping/course links first.
    //TODO: If groups or groupings are to be shared between courses, think again!
    if ($groupids = groups_get_groups($course->id)) {
        foreach ($groupids as $groupid) {
            if (groups_remove_all_members($groupid)) {
                if ($showfeedback) {
                    notify($strdeleted .' groups_members');
                }
            } else {
                $result = false;
            }
            /// Delete any associated context for this group ??
            delete_context(CONTEXT_GROUP, $groupid);

            if (groups_delete_group($groupid)) {
                if ($showfeedback) {
                    notify($strdeleted .' groups');
                }
            } else {
                $result = false;
            }
        }
    }
/// Delete any groupings.
    $result = groups_delete_all_groupings($course->id);
    if ($result && $showfeedback) {
        notify($strdeleted .' groupings');
    }

/// Delete all related records in other tables that may have a courseid
/// This array stores the tables that need to be cleared, as
/// table_name => column_name that contains the course id.

    $tablestoclear = array(
        'event' => 'courseid', // Delete events
        'log' => 'course', // Delete logs
        'course_sections' => 'course', // Delete any course stuff
        'course_modules' => 'course',
        'grade_category' => 'courseid', // Delete gradebook stuff
        'grade_exceptions' => 'courseid',
        'grade_item' => 'courseid',
        'grade_letter' => 'courseid',
        'grade_preferences' => 'courseid',
        'backup_courses' => 'courseid', // Delete scheduled backup stuff
        'backup_log' => 'courseid'
    );
    foreach ($tablestoclear as $table => $col) {
        if (delete_records($table, $col, $course->id)) {
            if ($showfeedback) {
                notify($strdeleted . ' ' . $table);
            }
        } else {
            $result = false;
        }
    }


/// Clean up metacourse stuff

    if ($course->metacourse) {
        delete_records("course_meta","parent_course",$course->id);
        sync_metacourse($course->id); // have to do it here so the enrolments get nuked. sync_metacourses won't find it without the id.
        if ($showfeedback) {
            notify("$strdeleted course_meta");
        }
    } else {
        if ($parents = get_records("course_meta","child_course",$course->id)) {
            foreach ($parents as $parent) {
                remove_from_metacourse($parent->parent_course,$parent->child_course); // this will do the unenrolments as well.
            }
            if ($showfeedback) {
                notify("$strdeleted course_meta");
            }
        }
    }

/// Delete questions and question categories
    include_once($CFG->libdir.'/questionlib.php');
    question_delete_course($course, $showfeedback);

/// Delete all roles and overiddes in the course context (but keep the course context)
    if ($courseid != SITEID) {
        delete_context(CONTEXT_COURSE, $course->id);
    }

    // fix for MDL-9016
    // clear the cache because the course context is deleted, and
    // we don't want to write assignment, overrides and context_rel table
    // with this old context id!
    get_context_instance('clearcache');
    return $result;
}


/**
 * This function will empty a course of USER data as much as
/// possible. It will retain the activities and the structure
/// of the course.
 *
 * @uses $USER
 * @uses $SESSION
 * @uses $CFG
 * @param object $data an object containing all the boolean settings and courseid
 * @param bool $showfeedback  if false then do it all silently
 * @return bool
 * @todo Finish documenting this function
 */
function reset_course_userdata($data, $showfeedback=true) {

    global $CFG, $USER, $SESSION;

    $result = true;

    $strdeleted = get_string('deleted');

    // Look in every instance of every module for data to delete

    if ($allmods = get_records('modules') ) {
        foreach ($allmods as $mod) {
            $modname = $mod->name;
            $modfile = $CFG->dirroot .'/mod/'. $modname .'/lib.php';
            $moddeleteuserdata = $modname .'_delete_userdata';   // Function to delete user data
            if (file_exists($modfile)) {
                @include_once($modfile);
                if (function_exists($moddeleteuserdata)) {
                    $moddeleteuserdata($data, $showfeedback);
                }
            }
        }
    } else {
        error('No modules are installed!');
    }

    // Delete other stuff
    $coursecontext = get_context_instance(CONTEXT_COURSE, $data->courseid);

    if (!empty($data->reset_students) or !empty($data->reset_teachers)) {
        $teachers     = array_keys(get_users_by_capability($coursecontext, 'moodle/course:update'));
        $participants = array_keys(get_users_by_capability($coursecontext, 'moodle/course:view'));
        $students     = array_diff($participants, $teachers);

        if (!empty($data->reset_students)) {
            foreach ($students as $studentid) {
                role_unassign(0, $studentid, 0, $coursecontext->id);
            }
            if ($showfeedback) {
                notify($strdeleted .' '.get_string('students'), 'notifysuccess');
            }

            /// Delete group members (but keep the groups) TODO:check.
            if ($groupids = groups_get_groups($data->courseid)) {
                foreach ($groupids as $groupid) {
                    if (groups_remove_all_group_members($groupid)) {
                        if ($showfeedback) {
                            notify($strdeleted .' groups_members', 'notifysuccess');
                        }
                    } else {
                        $result = false;
                    }
                }
            }
        }

        if (!empty($data->reset_teachers)) {
            foreach ($teachers as $teacherid) {
                role_unassign(0, $teacherid, 0, $coursecontext->id);
            }
            if ($showfeedback) {
                notify($strdeleted .' '.get_string('teachers'), 'notifysuccess');
            }
        }
    }

    if (!empty($data->reset_groups)) {
        if ($groupids = groups_get_groups($data->courseid)) {
            foreach ($groupids as $groupid) {
                if (groups_delete_group($groupid)) {
                    if ($showfeedback) {
                        notify($strdeleted .' groups', 'notifysuccess');
                    }
                } else {
                    $result = false;
                }
            }
        }
    }

    if (!empty($data->reset_events)) {
        if (delete_records('event', 'courseid', $data->courseid)) {
            if ($showfeedback) {
                notify($strdeleted .' event', 'notifysuccess');
            }
        } else {
            $result = false;
        }
    }

    if (!empty($data->reset_logs)) {
        if (delete_records('log', 'course', $data->courseid)) {
            if ($showfeedback) {
                notify($strdeleted .' log', 'notifysuccess');
            }
        } else {
            $result = false;
        }
    }

    // deletes all role assignments, and local override, these have no courseid in table and needs separate process
    $context = get_context_instance(CONTEXT_COURSE, $data->courseid);
    delete_records('role_capabilities', 'contextid', $context->id);

    return $result;
}


require_once($CFG->dirroot.'/group/lib.php');
/*TODO: functions moved to /group/lib/legacylib.php

ismember
add_user_to_group
mygroupid
groupmode
set_current_group
... */


function generate_email_processing_address($modid,$modargs) {
    global $CFG;

    if (empty($CFG->siteidentifier)) {    // Unique site identification code
        set_config('siteidentifier', random_string(32));
    }

    $header = $CFG->mailprefix . substr(base64_encode(pack('C',$modid)),0,2).$modargs;
    return $header . substr(md5($header.$CFG->siteidentifier),0,16).'@'.$CFG->maildomain;
}


function moodle_process_email($modargs,$body) {
    // the first char should be an unencoded letter. We'll take this as an action
    switch ($modargs{0}) {
        case 'B': { // bounce
            list(,$userid) = unpack('V',base64_decode(substr($modargs,1,8)));
            if ($user = get_record_select("user","id=$userid","id,email")) {
                // check the half md5 of their email
                $md5check = substr(md5($user->email),0,16);
                if ($md5check == substr($modargs, -16)) {
                    set_bounce_count($user);
                }
                // else maybe they've already changed it?
            }
        }
        break;
        // maybe more later?
    }
}

/// CORRESPONDENCE  ////////////////////////////////////////////////

/**
 * Send an email to a specified user
 *
 * @uses $CFG
 * @uses $FULLME
 * @uses SITEID
 * @param user $user  A {@link $USER} object
 * @param user $from A {@link $USER} object
 * @param string $subject plain text subject line of the email
 * @param string $messagetext plain text version of the message
 * @param string $messagehtml complete html version of the message (optional)
 * @param string $attachment a file on the filesystem, relative to $CFG->dataroot
 * @param string $attachname the name of the file (extension indicates MIME)
 * @param bool $usetrueaddress determines whether $from email address should
 *          be sent out. Will be overruled by user profile setting for maildisplay
 * @return bool|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
function email_to_user($user, $from, $subject, $messagetext, $messagehtml='', $attachment='', $attachname='', $usetrueaddress=true, $replyto='', $replytoname='') {

    global $CFG, $FULLME;

    include_once($CFG->libdir .'/phpmailer/class.phpmailer.php');

/// We are going to use textlib services here
    $textlib = textlib_get_instance();

    if (empty($user)) {
        return false;
    }

    // skip mail to suspended users
    if (isset($user->auth) && $user->auth=='nologin') {
        return true;
    }

    if (!empty($user->emailstop)) {
        return 'emailstop';
    }

    if (over_bounce_threshold($user)) {
        error_log("User $user->id (".fullname($user).") is over bounce threshold! Not sending.");
        return false;
    }

    $mail = new phpmailer;

    $mail->Version = 'Moodle '. $CFG->version;           // mailer version
    $mail->PluginDir = $CFG->libdir .'/phpmailer/';      // plugin directory (eg smtp plugin)

    $mail->CharSet = 'UTF-8';

    if ($CFG->smtphosts == 'qmail') {
        $mail->IsQmail();                              // use Qmail system

    } else if (empty($CFG->smtphosts)) {
        $mail->IsMail();                               // use PHP mail() = sendmail

    } else {
        $mail->IsSMTP();                               // use SMTP directly
        if (!empty($CFG->debugsmtp)) {
            echo '<pre>' . "\n";
            $mail->SMTPDebug = true;
        }
        $mail->Host = $CFG->smtphosts;               // specify main and backup servers

        if ($CFG->smtpuser) {                          // Use SMTP authentication
            $mail->SMTPAuth = true;
            $mail->Username = $CFG->smtpuser;
            $mail->Password = $CFG->smtppass;
        }
    }

    $adminuser = get_admin();

    // make up an email address for handling bounces
    if (!empty($CFG->handlebounces)) {
        $modargs = 'B'.base64_encode(pack('V',$user->id)).substr(md5($user->email),0,16);
        $mail->Sender = generate_email_processing_address(0,$modargs);
    }
    else {
        $mail->Sender   = $adminuser->email;
    }

    if (is_string($from)) { // So we can pass whatever we want if there is need
        $mail->From     = $CFG->noreplyaddress;
        $mail->FromName = $from;
    } else if ($usetrueaddress and $from->maildisplay) {
        $mail->From     = $from->email;
        $mail->FromName = fullname($from);
    } else {
        $mail->From     = $CFG->noreplyaddress;
        $mail->FromName = fullname($from);
        if (empty($replyto)) {
            $mail->AddReplyTo($CFG->noreplyaddress,get_string('noreplyname'));
        }
    }

    if (!empty($replyto)) {
        $mail->AddReplyTo($replyto,$replytoname);
    }

    $mail->Subject = substr(stripslashes($subject), 0, 900);

    $mail->AddAddress($user->email, fullname($user) );

    $mail->WordWrap = 79;                               // set word wrap

    if (!empty($from->customheaders)) {                 // Add custom headers
        if (is_array($from->customheaders)) {
            foreach ($from->customheaders as $customheader) {
                $mail->AddCustomHeader($customheader);
            }
        } else {
            $mail->AddCustomHeader($from->customheaders);
        }
    }

    if (!empty($from->priority)) {
        $mail->Priority = $from->priority;
    }

    if ($messagehtml && $user->mailformat == 1) { // Don't ever send HTML to users who don't want it
        $mail->IsHTML(true);
        $mail->Encoding = 'quoted-printable';           // Encoding to use
        $mail->Body    =  $messagehtml;
        $mail->AltBody =  "\n$messagetext\n";
    } else {
        $mail->IsHTML(false);
        $mail->Body =  "\n$messagetext\n";
    }

    if ($attachment && $attachname) {
        if (ereg( "\\.\\." ,$attachment )) {    // Security check for ".." in dir path
            $mail->AddAddress($adminuser->email, fullname($adminuser) );
            $mail->AddStringAttachment('Error in attachment.  User attempted to attach a filename with a unsafe name.', 'error.txt', '8bit', 'text/plain');
        } else {
            require_once($CFG->libdir.'/filelib.php');
            $mimetype = mimeinfo('type', $attachname);
            $mail->AddAttachment($CFG->dataroot .'/'. $attachment, $attachname, 'base64', $mimetype);
        }
    }



/// If we are running under Unicode and sitemailcharset or allowusermailcharset are set, convert the email
/// encoding to the specified one
    if ((!empty($CFG->sitemailcharset) || !empty($CFG->allowusermailcharset))) {
    /// Set it to site mail charset
        $charset = $CFG->sitemailcharset;
    /// Overwrite it with the user mail charset
        if (!empty($CFG->allowusermailcharset)) {
            if ($useremailcharset = get_user_preferences('mailcharset', '0', $user->id)) {
                $charset = $useremailcharset;
            }
        }
    /// If it has changed, convert all the necessary strings
        $charsets = get_list_of_charsets();
        unset($charsets['UTF-8']);
        if (in_array($charset, $charsets)) {
        /// Save the new mail charset
            $mail->CharSet = $charset;
        /// And convert some strings
            $mail->FromName = $textlib->convert($mail->FromName, 'utf-8', $mail->CharSet); //From Name
            foreach ($mail->ReplyTo as $key => $rt) {                                      //ReplyTo Names
                $mail->ReplyTo[$key][1] = $textlib->convert($rt, 'utf-8', $mail->CharSet);
            }
            $mail->Subject = $textlib->convert($mail->Subject, 'utf-8', $mail->CharSet);   //Subject
            foreach ($mail->to as $key => $to) {
                $mail->to[$key][1] = $textlib->convert($to, 'utf-8', $mail->CharSet);      //To Names
            }
            $mail->Body = $textlib->convert($mail->Body, 'utf-8', $mail->CharSet);         //Body
            $mail->AltBody = $textlib->convert($mail->AltBody, 'utf-8', $mail->CharSet);   //Subject
        }
    }

    if ($mail->Send()) {
        set_send_count($user);
        $mail->IsSMTP();                               // use SMTP directly
        if (!empty($CFG->debugsmtp)) {
            echo '</pre>';
        }
        return true;
    } else {
        mtrace('ERROR: '. $mail->ErrorInfo);
        add_to_log(SITEID, 'library', 'mailer', $FULLME, 'ERROR: '. $mail->ErrorInfo);
        if (!empty($CFG->debugsmtp)) {
            echo '</pre>';
        }
        return false;
    }
}

/**
 * Sets specified user's password and send the new password to the user via email.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return boolean|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
function setnew_password_and_mail($user) {

    global $CFG;

    $site  = get_site();
    $from = get_admin();

    $newpassword = generate_password();

    if (! set_field('user', 'password', md5($newpassword), 'id', $user->id) ) {
        trigger_error('Could not set user password!');
        return false;
    }

    $a = new object();
    $a->firstname   = $user->firstname;
    $a->sitename    = format_string($site->fullname);
    $a->username    = $user->username;
    $a->newpassword = $newpassword;
    $a->link        = $CFG->wwwroot .'/login/';
    $a->signoff     = fullname($from, true).' ('. $from->email .')';

    $message = get_string('newusernewpasswordtext', '', $a);

    $subject  = format_string($site->fullname) .': '. get_string('newusernewpasswordsubj');

    return email_to_user($user, $from, $subject, $message);

}

/**
 * Resets specified user's password and send the new password to the user via email.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return bool|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
function reset_password_and_mail($user) {

    global $CFG;

    $site  = get_site();
    $from = get_admin();

    $userauth = get_auth_plugin($user->auth);
    if (!$userauth->can_reset_password()) {
        trigger_error("Attempt to reset user password for user $user->username with Auth $user->auth.");
        return false;
    }

    $newpassword = generate_password();

    if (!$userauth->user_update_password(addslashes_recursive($user), addslashes($newpassword))) {
        error("Could not set user password!");
    }

    $a = new object();
    $a->firstname = $user->firstname;
    $a->sitename = format_string($site->fullname);
    $a->username = $user->username;
    $a->newpassword = $newpassword;
    $a->link = $CFG->httpswwwroot .'/login/change_password.php';
    $a->signoff = fullname($from, true).' ('. $from->email .')';

    $message = get_string('newpasswordtext', '', $a);

    $subject  = format_string($site->fullname) .': '. get_string('changedpassword');

    return email_to_user($user, $from, $subject, $message);

}

/**
 * Send email to specified user with confirmation text and activation link.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return bool|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
 function send_confirmation_email($user) {

    global $CFG;

    $site = get_site();
    $from = get_admin();

    $data = new object();
    $data->firstname = fullname($user);
    $data->sitename = format_string($site->fullname);
    $data->admin = fullname($from) .' ('. $from->email .')';

    $subject = get_string('emailconfirmationsubject', '', format_string($site->fullname));

    $data->link = $CFG->wwwroot .'/login/confirm.php?data='. $user->secret .'/'. urlencode($user->username);
    $message     = get_string('emailconfirmation', '', $data);
    $messagehtml = text_to_html(get_string('emailconfirmation', '', $data), false, false, true);

    $user->mailformat = 1;  // Always send HTML version as well

    return email_to_user($user, $from, $subject, $message, $messagehtml);

}

/**
 * send_password_change_confirmation_email.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return bool|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
function send_password_change_confirmation_email($user) {

    global $CFG;

    $site = get_site();
    $from = get_admin();

    $data = new object();
    $data->firstname = $user->firstname;
    $data->sitename = format_string($site->fullname);
    $data->link = $CFG->httpswwwroot .'/login/forgot_password.php?p='. $user->secret .'&s='. urlencode($user->username);
    $data->admin = fullname($from).' ('. $from->email .')';

    $message = get_string('emailpasswordconfirmation', '', $data);
    $subject = get_string('emailpasswordconfirmationsubject', '', format_string($site->fullname));

    return email_to_user($user, $from, $subject, $message);

}

/**
 * send_password_change_info.
 *
 * @uses $CFG
 * @param user $user A {@link $USER} object
 * @return bool|string Returns "true" if mail was sent OK, "emailstop" if email
 *          was blocked by user and "false" if there was another sort of error.
 */
function send_password_change_info($user) {

    global $CFG;

    $site = get_site();
    $from = get_admin();

    $data = new object();
    $data->firstname = $user->firstname;
    $data->sitename = format_string($site->fullname);
    $data->admin = fullname($from).' ('. $from->email .')';

     $userauth = get_auth_plugin($user->auth);
    if ($userauth->can_change_password() and $userauth->change_password_url()) {
        // we have some external url for password cahnging
        $data->link .= $userauth->change_password_url();

    } else {
        //no way to change password, sorry
        $data->link = '';
    }

    if (!empty($data->link)) {
        $message = get_string('emailpasswordchangeinfo', '', $data);
        $subject = get_string('emailpasswordchangeinfosubject', '', format_string($site->fullname));
    } else {
        $message = get_string('emailpasswordchangeinfofail', '', $data);
        $subject = get_string('emailpasswordchangeinfosubject', '', format_string($site->fullname));
    }

    return email_to_user($user, $from, $subject, $message);

}

/**
 * Check that an email is allowed.  It returns an error message if there
 * was a problem.
 *
 * @uses $CFG
 * @param  string $email Content of email
 * @return string|false
 */
function email_is_not_allowed($email) {

    global $CFG;

    if (!empty($CFG->allowemailaddresses)) {
        $allowed = explode(' ', $CFG->allowemailaddresses);
        foreach ($allowed as $allowedpattern) {
            $allowedpattern = trim($allowedpattern);
            if (!$allowedpattern) {
                continue;
            }
            if (strpos($allowedpattern, '.') === 0) {
                if (strpos(strrev($email), strrev($allowedpattern)) === 0) {
                    // subdomains are in a form ".example.com" - matches "xxx@anything.example.com"
                    return false;
                }

            } else if (strpos(strrev($email), strrev('@'.$allowedpattern)) === 0) { // Match!   (bug 5250)
                return false;
            }
        }
        return get_string('emailonlyallowed', '', $CFG->allowemailaddresses);

    } else if (!empty($CFG->denyemailaddresses)) {
        $denied = explode(' ', $CFG->denyemailaddresses);
        foreach ($denied as $deniedpattern) {
            $deniedpattern = trim($deniedpattern);
            if (!$deniedpattern) {
                continue;
            }
            if (strpos($deniedpattern, '.') === 0) {
                if (strpos(strrev($email), strrev($deniedpattern)) === 0) {
                    // subdomains are in a form ".example.com" - matches "xxx@anything.example.com"
                    return get_string('emailnotallowed', '', $CFG->denyemailaddresses);
                }

            } else if (strpos(strrev($email), strrev('@'.$deniedpattern)) === 0) { // Match!   (bug 5250)
                return get_string('emailnotallowed', '', $CFG->denyemailaddresses);
            }
        }
    }

    return false;
}

function email_welcome_message_to_user($course, $user=NULL) {
    global $CFG, $USER;

    if (empty($user)) {
        if (!isloggedin()) {
            return false;
        }
        $user = $USER;
    }

    if (!empty($course->welcomemessage)) {
        $subject = get_string('welcometocourse', '', format_string($course->fullname));

        $a->coursename = $course->fullname;
        $a->profileurl = "$CFG->wwwroot/user/view.php?id=$USER->id&course=$course->id";
        //$message = get_string("welcometocoursetext", "", $a);
        $message = $course->welcomemessage;

        if (! $teacher = get_teacher($course->id)) {
            $teacher = get_admin();
        }
        email_to_user($user, $teacher, $subject, $message);
    }
}

/// FILE HANDLING  /////////////////////////////////////////////


/**
 * Makes an upload directory for a particular module.
 *
 * @uses $CFG
 * @param int $courseid The id of the course in question - maps to id field of 'course' table.
 * @return string|false Returns full path to directory if successful, false if not
 */
function make_mod_upload_directory($courseid) {
    global $CFG;

    if (! $moddata = make_upload_directory($courseid .'/'. $CFG->moddata)) {
        return false;
    }

    $strreadme = get_string('readme');

    if (file_exists($CFG->dirroot .'/lang/'. $CFG->lang .'/docs/module_files.txt')) {
        copy($CFG->dirroot .'/lang/'. $CFG->lang .'/docs/module_files.txt', $moddata .'/'. $strreadme .'.txt');
    } else {
        copy($CFG->dirroot .'/lang/en_utf8/docs/module_files.txt', $moddata .'/'. $strreadme .'.txt');
    }
    return $moddata;
}

/**
 * Makes a directory for a particular user.
 *
 * @uses $CFG
 * @param int $userid The id of the user in question - maps to id field of 'user' table.
 * @param bool $test Whether we are only testing the return value (do not create the directory)
 * @return string|false Returns full path to directory if successful, false if not
 */
function make_user_directory($userid, $test=false) {
    global $CFG;

    if (is_bool($userid) || $userid < 0 || !ereg('^[0-9]{1,10}$', $userid) || $userid > 2147483647) {
        if (!$test) {
            notify("Given userid was not a valid integer! (" . gettype($userid) . " $userid)");
        }
        return false;
    }

    // Generate a two-level path for the userid. First level groups them by slices of 1000 users, second level is userid
    $level1 = floor($userid / 1000) * 1000;

    $userdir = "user/$level1/$userid";
    if ($test) {
        return $CFG->dataroot . '/' . $userdir;
    } else {
        return make_upload_directory($userdir);
        }
    }

/**
 * Returns an array of full paths to user directories, indexed by their userids.
 *
 * @param bool $only_non_empty Only return directories that contain files
 * @param bool $legacy Search for user directories in legacy location (dataroot/users/userid) instead of (dataroot/user/section/userid)
 * @return array An associative array: userid=>array(basedir => $basedir, userfolder => $userfolder) 
 */
function get_user_directories($only_non_empty=true, $legacy=false) {
    global $CFG;

    $rootdir = $CFG->dataroot."/user";
    
    if ($legacy) {
        $rootdir = $CFG->dataroot."/users"; 
    }
    $dirlist = array();

    //Check if directory exists 
    if (check_dir_exists($rootdir, true)) { 
        if ($legacy) {
            if ($userlist = get_directory_list($rootdir, '', true, true, false)) {
                foreach ($userlist as $userid) {
                    $dirlist[$userid] = array('basedir' => $rootdir, 'userfolder' => $userid);
                }
            } else {
                notify("no directories found under $rootdir");
            } 
        } else {
            if ($grouplist =get_directory_list($rootdir, '', true, true, false)) { // directories will be in the form 0, 1000, 2000 etc...
                foreach ($grouplist as $group) {
                    if ($userlist = get_directory_list("$rootdir/$group", '', true, true, false)) {
                        foreach ($userlist as $userid) {
                            $dirlist[$userid] = array('basedir' => $rootdir, 'userfolder' => $group . '/' . $userid);
                        }
                    }
                }
            } 
        }
    } else {
        notify("$rootdir does not exist!");
        return false;
    }
    return $dirlist;
}

/**
 * Returns current name of file on disk if it exists.
 *
 * @param string $newfile File to be verified
 * @return string Current name of file on disk if true
 */
function valid_uploaded_file($newfile) {
    if (empty($newfile)) {
        return '';
    }
    if (is_uploaded_file($newfile['tmp_name']) and $newfile['size'] > 0) {
        return $newfile['tmp_name'];
    } else {
        return '';
    }
}

/**
 * Returns the maximum size for uploading files.
 *
 * There are seven possible upload limits:
 * 1. in Apache using LimitRequestBody (no way of checking or changing this)
 * 2. in php.ini for 'upload_max_filesize' (can not be changed inside PHP)
 * 3. in .htaccess for 'upload_max_filesize' (can not be changed inside PHP)
 * 4. in php.ini for 'post_max_size' (can not be changed inside PHP)
 * 5. by the Moodle admin in $CFG->maxbytes
 * 6. by the teacher in the current course $course->maxbytes
 * 7. by the teacher for the current module, eg $assignment->maxbytes
 *
 * These last two are passed to this function as arguments (in bytes).
 * Anything defined as 0 is ignored.
 * The smallest of all the non-zero numbers is returned.
 *
 * @param int $sizebytes ?
 * @param int $coursebytes Current course $course->maxbytes (in bytes)
 * @param int $modulebytes Current module ->maxbytes (in bytes)
 * @return int The maximum size for uploading files.
 * @todo Finish documenting this function
 */
function get_max_upload_file_size($sitebytes=0, $coursebytes=0, $modulebytes=0) {

    if (! $filesize = ini_get('upload_max_filesize')) {
        $filesize = '5M';
    }
    $minimumsize = get_real_size($filesize);

    if ($postsize = ini_get('post_max_size')) {
        $postsize = get_real_size($postsize);
        if ($postsize < $minimumsize) {
            $minimumsize = $postsize;
        }
    }

    if ($sitebytes and $sitebytes < $minimumsize) {
        $minimumsize = $sitebytes;
    }

    if ($coursebytes and $coursebytes < $minimumsize) {
        $minimumsize = $coursebytes;
    }

    if ($modulebytes and $modulebytes < $minimumsize) {
        $minimumsize = $modulebytes;
    }

    return $minimumsize;
}

/**
 * Related to {@link get_max_upload_file_size()} - this function returns an
 * array of possible sizes in an array, translated to the
 * local language.
 *
 * @uses SORT_NUMERIC
 * @param int $sizebytes ?
 * @param int $coursebytes Current course $course->maxbytes (in bytes)
 * @param int $modulebytes Current module ->maxbytes (in bytes)
 * @return int
 * @todo Finish documenting this function
 */
function get_max_upload_sizes($sitebytes=0, $coursebytes=0, $modulebytes=0) {

    if (!$maxsize = get_max_upload_file_size($sitebytes, $coursebytes, $modulebytes)) {
        return array();
    }

    $filesize[$maxsize] = display_size($maxsize);

    $sizelist = array(10240, 51200, 102400, 512000, 1048576, 2097152,
                      5242880, 10485760, 20971520, 52428800, 104857600);

    foreach ($sizelist as $sizebytes) {
       if ($sizebytes < $maxsize) {
           $filesize[$sizebytes] = display_size($sizebytes);
       }
    }

    krsort($filesize, SORT_NUMERIC);

    return $filesize;
}

/**
 * If there has been an error uploading a file, print the appropriate error message
 * Numerical constants used as constant definitions not added until PHP version 4.2.0
 *
 * $filearray is a 1-dimensional sub-array of the $_FILES array
 * eg $filearray = $_FILES['userfile1']
 * If left empty then the first element of the $_FILES array will be used
 *
 * @uses $_FILES
 * @param array $filearray  A 1-dimensional sub-array of the $_FILES array
 * @param bool $returnerror If true then a string error message will be returned. Otherwise the user will be notified of the error in a notify() call.
 * @return bool|string
 */
function print_file_upload_error($filearray = '', $returnerror = false) {

    if ($filearray == '' or !isset($filearray['error'])) {

        if (empty($_FILES)) return false;

        $files = $_FILES; /// so we don't mess up the _FILES array for subsequent code
        $filearray = array_shift($files); /// use first element of array
    }

    switch ($filearray['error']) {

        case 0: // UPLOAD_ERR_OK
            if ($filearray['size'] > 0) {
                $errmessage = get_string('uploadproblem', $filearray['name']);
            } else {
                $errmessage = get_string('uploadnofilefound'); /// probably a dud file name
            }
            break;

        case 1: // UPLOAD_ERR_INI_SIZE
            $errmessage = get_string('uploadserverlimit');
            break;

        case 2: // UPLOAD_ERR_FORM_SIZE
            $errmessage = get_string('uploadformlimit');
            break;

        case 3: // UPLOAD_ERR_PARTIAL
            $errmessage = get_string('uploadpartialfile');
            break;

        case 4: // UPLOAD_ERR_NO_FILE
            $errmessage = get_string('uploadnofilefound');
            break;

        default:
            $errmessage = get_string('uploadproblem', $filearray['name']);
    }

    if ($returnerror) {
        return $errmessage;
    } else {
        notify($errmessage);
        return true;
    }

}

/**
 * handy function to loop through an array of files and resolve any filename conflicts
 * both in the array of filenames and for what is already on disk.
 * not really compatible with the similar function in uploadlib.php
 * but this could be used for files/index.php for moving files around.
 */

function resolve_filename_collisions($destination,$files,$format='%s_%d.%s') {
    foreach ($files as $k => $f) {
        if (check_potential_filename($destination,$f,$files)) {
            $bits = explode('.', $f);
            for ($i = 1; true; $i++) {
                $try = sprintf($format, $bits[0], $i, $bits[1]);
                if (!check_potential_filename($destination,$try,$files)) {
                    $files[$k] = $try;
                    break;
                }
            }
        }
    }
    return $files;
}

/**
 * @used by resolve_filename_collisions
 */
function check_potential_filename($destination,$filename,$files) {
    if (file_exists($destination.'/'.$filename)) {
        return true;
    }
    if (count(array_keys($files,$filename)) > 1) {
        return true;
    }
    return false;
}


/**
 * Returns an array with all the filenames in
 * all subdirectories, relative to the given rootdir.
 * If excludefile is defined, then that file/directory is ignored
 * If getdirs is true, then (sub)directories are included in the output
 * If getfiles is true, then files are included in the output
 * (at least one of these must be true!)
 *
 * @param string $rootdir  ?
 * @param string $excludefile  If defined then the specified file/directory is ignored
 * @param bool $descend  ?
 * @param bool $getdirs  If true then (sub)directories are included in the output
 * @param bool $getfiles  If true then files are included in the output
 * @return array An array with all the filenames in
 * all subdirectories, relative to the given rootdir
 * @todo Finish documenting this function. Add examples of $excludefile usage.
 */
function get_directory_list($rootdir, $excludefiles='', $descend=true, $getdirs=false, $getfiles=true) {

    $dirs = array();

    if (!$getdirs and !$getfiles) {   // Nothing to show
        return $dirs;
    }

    if (!is_dir($rootdir)) {          // Must be a directory
        return $dirs;
    }

    if (!$dir = opendir($rootdir)) {  // Can't open it for some reason
        return $dirs;
    }

    if (!is_array($excludefiles)) {
        $excludefiles = array($excludefiles);
    }

    while (false !== ($file = readdir($dir))) {
        $firstchar = substr($file, 0, 1);
        if ($firstchar == '.' or $file == 'CVS' or in_array($file, $excludefiles)) {
            continue;
        }
        $fullfile = $rootdir .'/'. $file;
        if (filetype($fullfile) == 'dir') {
            if ($getdirs) {
                $dirs[] = $file;
            }
            if ($descend) {
                $subdirs = get_directory_list($fullfile, $excludefiles, $descend, $getdirs, $getfiles);
                foreach ($subdirs as $subdir) {
                    $dirs[] = $file .'/'. $subdir;
                }
            }
        } else if ($getfiles) {
            $dirs[] = $file;
        }
    }
    closedir($dir);

    asort($dirs);

    return $dirs;
}


/**
 * Adds up all the files in a directory and works out the size.
 *
 * @param string $rootdir  ?
 * @param string $excludefile  ?
 * @return array
 * @todo Finish documenting this function
 */
function get_directory_size($rootdir, $excludefile='') {

    global $CFG;

    // do it this way if we can, it's much faster
    if (!empty($CFG->pathtodu) && is_executable(trim($CFG->pathtodu))) {
        $command = trim($CFG->pathtodu).' -sk --apparent-size '.escapeshellarg($rootdir);
        $output = null;
        $return = null;
        exec($command,$output,$return);
        if (is_array($output)) {
            return get_real_size(intval($output[0]).'k'); // we told it to return k.
        }
    }

    if (!is_dir($rootdir)) {          // Must be a directory
        return 0;
    }

    if (!$dir = @opendir($rootdir)) {  // Can't open it for some reason
        return 0;
    }

    $size = 0;

    while (false !== ($file = readdir($dir))) {
        $firstchar = substr($file, 0, 1);
        if ($firstchar == '.' or $file == 'CVS' or $file == $excludefile) {
            continue;
        }
        $fullfile = $rootdir .'/'. $file;
        if (filetype($fullfile) == 'dir') {
            $size += get_directory_size($fullfile, $excludefile);
        } else {
            $size += filesize($fullfile);
        }
    }
    closedir($dir);

    return $size;
}

/**
 * Converts bytes into display form
 *
 * @param string $size  ?
 * @return string
 * @staticvar string $gb Localized string for size in gigabytes
 * @staticvar string $mb Localized string for size in megabytes
 * @staticvar string $kb Localized string for size in kilobytes
 * @staticvar string $b Localized string for size in bytes
 * @todo Finish documenting this function. Verify return type.
 */
function display_size($size) {

    static $gb, $mb, $kb, $b;

    if (empty($gb)) {
        $gb = get_string('sizegb');
        $mb = get_string('sizemb');
        $kb = get_string('sizekb');
        $b  = get_string('sizeb');
    }

    if ($size >= 1073741824) {
        $size = round($size / 1073741824 * 10) / 10 . $gb;
    } else if ($size >= 1048576) {
        $size = round($size / 1048576 * 10) / 10 . $mb;
    } else if ($size >= 1024) {
        $size = round($size / 1024 * 10) / 10 . $kb;
    } else {
        $size = $size .' '. $b;
    }
    return $size;
}

/**
 * Cleans a given filename by removing suspicious or troublesome characters
 * Only these are allowed: alphanumeric _ - .
 * Unicode characters can be enabled by setting $CFG->unicodecleanfilename = true in config.php
 *
 * WARNING: unicode characters may not be compatible with zip compression in backup/restore,
 *          because native zip binaries do weird character conversions. Use PHP zipping instead.
 *
 * @param string $string  file name
 * @return string cleaned file name
 */
function clean_filename($string) {
    global $CFG;
    if (empty($CFG->unicodecleanfilename)) {
        $textlib = textlib_get_instance();
        $string = $textlib->specialtoascii($string);
        $string = preg_replace('/[^\.a-zA-Z\d\_-]/','_', $string ); // only allowed chars
    } else {
        //clean only ascii range
        $string = preg_replace("/[\\000-\\x2c\\x2f\\x3a-\\x40\\x5b-\\x5e\\x60\\x7b-\\177]/s", '_', $string);
    }
    $string = preg_replace("/_+/", '_', $string);
    $string = preg_replace("/\.\.+/", '.', $string);
    return $string;
}


/// STRING TRANSLATION  ////////////////////////////////////////

/**
 * Returns the code for the current language
 *
 * @uses $CFG
 * @param $USER
 * @param $SESSION
 * @return string
 */
function current_language() {
    global $CFG, $USER, $SESSION, $COURSE;

    if (!empty($COURSE->id) and $COURSE->id != SITEID and !empty($COURSE->lang)) {    // Course language can override all other settings for this page
        $return = $COURSE->lang;

    } else if (!empty($SESSION->lang)) {    // Session language can override other settings
        $return = $SESSION->lang;

    } else if (!empty($USER->lang)) {
        $return = $USER->lang;

    } else {
        $return = $CFG->lang;
    }

    if ($return == 'en') {
        $return = 'en_utf8';
    }

    return $return;
}

/**
 * Prints out a translated string.
 *
 * Prints out a translated string using the return value from the {@link get_string()} function.
 *
 * Example usage of this function when the string is in the moodle.php file:<br/>
 * <code>
 * echo '<strong>';
 * print_string('wordforstudent');
 * echo '</strong>';
 * </code>
 *
 * Example usage of this function when the string is not in the moodle.php file:<br/>
 * <code>
 * echo '<h1>';
 * print_string('typecourse', 'calendar');
 * echo '</h1>';
 * </code>
 *
 * @param string $identifier The key identifier for the localized string
 * @param string $module The module where the key identifier is stored. If none is specified then moodle.php is used.
 * @param mixed $a An object, string or number that can be used
 * within translation strings
 */
function print_string($identifier, $module='', $a=NULL) {
    echo get_string($identifier, $module, $a);
}

/**
 * fix up the optional data in get_string()/print_string() etc
 * ensure possible sprintf() format characters are escaped correctly
 * needs to handle arbitrary strings and objects
 * @param mixed $a An object, string or number that can be used
 * @return mixed the supplied parameter 'cleaned'
 */
function clean_getstring_data( $a ) {
    if (is_string($a)) {
        return str_replace( '%','%%',$a );
    }
    elseif (is_object($a)) {
        $a_vars = get_object_vars( $a );
        $new_a_vars = array();
        foreach ($a_vars as $fname => $a_var) {
            $new_a_vars[$fname] = clean_getstring_data( $a_var );
        }
        return (object)$new_a_vars;
    }
    else {
        return $a;
    }
}

/**
 * @return array places to look for lang strings based on the prefix to the
 * module name. For example qtype_ in question/type. Used by get_string and
 * help.php.
 */
function places_to_search_for_lang_strings() {
    global $CFG;

    return array(
        '__exceptions' => array('moodle', 'langconfig'),
        'assignment_' => array('mod/assignment/type'),
        'auth_' => array('auth'),
        'block_' => array('blocks'),
        'datafield_' => array('mod/data/field'),
        'datapreset_' => array('mod/data/preset'),
        'enrol_' => array('enrol'),
        'format_' => array('course/format'),
        'qtype_' => array('question/type'),
        'quiz_' => array('mod/quiz/report'),
        'report_' => array($CFG->admin.'/report', 'course/report'),
        'resource_' => array('mod/resource/type'),
        'profilefield_' => array('user/profile/field'),
        '' => array('mod')
    );
}

/**
 * Returns a localized string.
 *
 * Returns the translated string specified by $identifier as
 * for $module.  Uses the same format files as STphp.
 * $a is an object, string or number that can be used
 * within translation strings
 *
 * eg "hello \$a->firstname \$a->lastname"
 * or "hello \$a"
 *
 * If you would like to directly echo the localized string use
 * the function {@link print_string()}
 *
 * Example usage of this function involves finding the string you would
 * like a local equivalent of and using its identifier and module information
 * to retrive it.<br/>
 * If you open moodle/lang/en/moodle.php and look near line 1031
 * you will find a string to prompt a user for their word for student
 * <code>
 * $string['wordforstudent'] = 'Your word for Student';
 * </code>
 * So if you want to display the string 'Your word for student'
 * in any language that supports it on your site
 * you just need to use the identifier 'wordforstudent'
 * <code>
 * $mystring = '<strong>'. get_string('wordforstudent') .'</strong>';
or
 * </code>
 * If the string you want is in another file you'd take a slightly
 * different approach. Looking in moodle/lang/en/calendar.php you find
 * around line 75:
 * <code>
 * $string['typecourse'] = 'Course event';
 * </code>
 * If you want to display the string "Course event" in any language
 * supported you would use the identifier 'typecourse' and the module 'calendar'
 * (because it is in the file calendar.php):
 * <code>
 * $mystring = '<h1>'. get_string('typecourse', 'calendar') .'</h1>';
 * </code>
 *
 * As a last resort, should the identifier fail to map to a string
 * the returned string will be [[ $identifier ]]
 *
 * @uses $CFG
 * @param string $identifier The key identifier for the localized string
 * @param string $module The module where the key identifier is stored. If none is specified then moodle.php is used.
 * @param mixed $a An object, string or number that can be used
 * within translation strings
 * @param array $extralocations An array of strings with other locations to look for string files
 * @return string The localized string.
 */
function get_string($identifier, $module='', $a=NULL, $extralocations=NULL) {

    global $CFG;

/// originally these special strings were stored in moodle.php now we are only in langconfig.php
    $langconfigstrs = array('alphabet', 'backupnameformat', 'firstdayofweek', 'locale',
                            'localewin', 'localewincharset', 'oldcharset',
                            'parentlanguage', 'strftimedate', 'strftimedateshort', 'strftimedatetime',
                            'strftimedaydate', 'strftimedaydatetime', 'strftimedayshort', 'strftimedaytime',
                            'strftimemonthyear', 'strftimerecent', 'strftimerecentfull', 'strftimetime',
                            'thischarset', 'thisdirection', 'thislanguage');

    $filetocheck = 'langconfig.php';
    $defaultlang = 'en_utf8';
    if (in_array($identifier, $langconfigstrs)) {
        $module = 'langconfig';  //This strings are under langconfig.php for 1.6 lang packs
    }

    $lang = current_language();

    if ($module == '') {
        $module = 'moodle';
    }

    // if $a happens to have % in it, double it so sprintf() doesn't break
    if ($a) {
        $a = clean_getstring_data( $a );
    }

/// Define the two or three major locations of language strings for this module
    $locations = array();

    if (!empty($extralocations)) {   // Calling code has a good idea where to look
        if (is_array($extralocations)) {
            $locations += $extralocations;
        } else if (is_string($extralocations)) {
            $locations[] = $extralocations;
        } else {
            debugging('Bad lang path provided');
        }
    }

    if (isset($CFG->running_installer)) {
        $module = 'installer';
        $filetocheck = 'installer.php';
        $locations[] = $CFG->dirroot.'/install/lang/';
        $locations[] = $CFG->dataroot.'/lang/';
        $locations[] = $CFG->dirroot.'/lang/';
        $defaultlang = 'en_utf8';
    } else {
        $locations[] = $CFG->dataroot.'/lang/';
        $locations[] = $CFG->dirroot.'/lang/';
    }

/// Add extra places to look for strings for particular plugin types.
    $rules = places_to_search_for_lang_strings();
    $exceptions = $rules['__exceptions'];
    unset($rules['__exceptions']);

    if (!in_array($module, $exceptions)) {
        $dividerpos = strpos($module, '_');
        if ($dividerpos === false) {
            $type = '';
            $plugin = $module;
        } else {
            $type = substr($module, 0, $dividerpos + 1);
            $plugin = substr($module, $dividerpos + 1);
        }
        if (!empty($rules[$type])) {
            foreach ($rules[$type] as $location) {
                $locations[] = $CFG->dirroot . "/$location/$plugin/lang/";
            }
        }
    }

/// First check all the normal locations for the string in the current language
    $resultstring = '';
    foreach ($locations as $location) {
        $locallangfile = $location.$lang.'_local'.'/'.$module.'.php';    //first, see if there's a local file
        if (file_exists($locallangfile)) {
            if ($result = get_string_from_file($identifier, $locallangfile, "\$resultstring")) {
                eval($result);
                return $resultstring;
            }
        }
        //if local directory not found, or particular string does not exist in local direcotry
        $langfile = $location.$lang.'/'.$module.'.php';
        if (file_exists($langfile)) {
            if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                eval($result);
                return $resultstring;
            }
        }
    }

/// If the preferred language was English (utf8) we can abort now
/// saving some checks beacuse it's the only "root" lang
    if ($lang == 'en_utf8') {
        return '[['. $identifier .']]';
    }

/// Is a parent language defined?  If so, try to find this string in a parent language file

    foreach ($locations as $location) {
        $langfile = $location.$lang.'/'.$filetocheck;
        if (file_exists($langfile)) {
            if ($result = get_string_from_file('parentlanguage', $langfile, "\$parentlang")) {
                eval($result);
                if (!empty($parentlang)) {   // found it!

                    //first, see if there's a local file for parent
                    $locallangfile = $location.$parentlang.'_local'.'/'.$module.'.php';
                    if (file_exists($locallangfile)) {
                        if ($result = get_string_from_file($identifier, $locallangfile, "\$resultstring")) {
                            eval($result);
                            return $resultstring;
                        }
                    }

                    //if local directory not found, or particular string does not exist in local direcotry
                    $langfile = $location.$parentlang.'/'.$module.'.php';
                    if (file_exists($langfile)) {
                        if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                            eval($result);
                            return $resultstring;
                        }
                    }
                }
            }
        }
    }

/// Our only remaining option is to try English

    foreach ($locations as $location) {
        $locallangfile = $location.$defaultlang.'_local/'.$module.'.php';    //first, see if there's a local file
        if (file_exists($locallangfile)) {
            if ($result = get_string_from_file($identifier, $locallangfile, "\$resultstring")) {
                eval($result);
                return $resultstring;
            }
        }

        //if local_en not found, or string not found in local_en
        $langfile = $location.$defaultlang.'/'.$module.'.php';

        if (file_exists($langfile)) {
            if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                eval($result);
                return $resultstring;
            }
        }
    }

/// And, because under 1.6 en is defined as en_utf8 child, me must try
/// if it hasn't been queried before.
    if ($defaultlang  == 'en') {
        $defaultlang = 'en_utf8';
        foreach ($locations as $location) {
            $locallangfile = $location.$defaultlang.'_local/'.$module.'.php';    //first, see if there's a local file
            if (file_exists($locallangfile)) {
                if ($result = get_string_from_file($identifier, $locallangfile, "\$resultstring")) {
                    eval($result);
                    return $resultstring;
                }
            }

            //if local_en not found, or string not found in local_en
            $langfile = $location.$defaultlang.'/'.$module.'.php';

            if (file_exists($langfile)) {
                if ($result = get_string_from_file($identifier, $langfile, "\$resultstring")) {
                    eval($result);
                    return $resultstring;
                }
            }
        }
    }

    return '[['.$identifier.']]';  // Last resort
}

/**
 * This function is only used from {@link get_string()}.
 *
 * @internal Only used from get_string, not meant to be public API
 * @param string $identifier ?
 * @param string $langfile ?
 * @param string $destination ?
 * @return string|false ?
 * @staticvar array $strings Localized strings
 * @access private
 * @todo Finish documenting this function.
 */
function get_string_from_file($identifier, $langfile, $destination) {

    static $strings;    // Keep the strings cached in memory.

    if (empty($strings[$langfile])) {
        $string = array();
        include ($langfile);
        $strings[$langfile] = $string;
    } else {
        $string = &$strings[$langfile];
    }

    if (!isset ($string[$identifier])) {
        return false;
    }

    return $destination .'= sprintf("'. $string[$identifier] .'");';
}

/**
 * Converts an array of strings to their localized value.
 *
 * @param array $array An array of strings
 * @param string $module The language module that these strings can be found in.
 * @return string
 */
function get_strings($array, $module='') {

   $string = NULL;
   foreach ($array as $item) {
       $string->$item = get_string($item, $module);
   }
   return $string;
}

/**
 * Returns a list of language codes and their full names
 * hides the _local files from everyone.
 * @param bool refreshcache force refreshing of lang cache
 * @param bool returnall ignore langlist, return all languages available
 * @return array An associative array with contents in the form of LanguageCode => LanguageName
 */
function get_list_of_languages($refreshcache=false, $returnall=false) {

    global $CFG;

    $languages = array();

    $filetocheck = 'langconfig.php';

    if (!$refreshcache && !$returnall && !empty($CFG->langcache) && file_exists($CFG->dataroot .'/cache/languages')) {
/// read available langs from cache

        $lines = file($CFG->dataroot .'/cache/languages');
        foreach ($lines as $line) {
            $line = trim($line);
            if (preg_match('/^(\w+)\s+(.+)/', $line, $matches)) {
                $languages[$matches[1]] = $matches[2];
            }
        }
        unset($lines); unset($line); unset($matches);
        return $languages;
    }

    if (!$returnall && !empty($CFG->langlist)) {
/// return only languages allowed in langlist admin setting

        $langlist = explode(',', $CFG->langlist);
        // fix short lang names first - non existing langs are skipped anyway...
        foreach ($langlist as $lang) {
            if (strpos($lang, '_utf8') === false) {
                $langlist[] = $lang.'_utf8';
            }
        }
        // find existing langs from langlist
        foreach ($langlist as $lang) {
            $lang = trim($lang);   //Just trim spaces to be a bit more permissive
            if (strstr($lang, '_local')!==false) {
                continue;
            }
            if (substr($lang, -5) == '_utf8') {   //Remove the _utf8 suffix from the lang to show
                $shortlang = substr($lang, 0, -5);
            } else {
                $shortlang = $lang;
            }
        /// Search under dirroot/lang
            if (file_exists($CFG->dirroot .'/lang/'. $lang .'/'. $filetocheck)) {
                include($CFG->dirroot .'/lang/'. $lang .'/'. $filetocheck);
                if (!empty($string['thislanguage'])) {
                    $languages[$lang] = $string['thislanguage'].' ('. $shortlang .')';
                }
                unset($string);
            }
        /// And moodledata/lang
            if (file_exists($CFG->dataroot .'/lang/'. $lang .'/'. $filetocheck)) {
                include($CFG->dataroot .'/lang/'. $lang .'/'. $filetocheck);
                if (!empty($string['thislanguage'])) {
                    $languages[$lang] = $string['thislanguage'].' ('. $shortlang .')';
                }
                unset($string);
            }
        }

    } else {
/// return all languages available in system
    /// Fetch langs from moodle/lang directory
        $langdirs = get_list_of_plugins('lang');
    /// Fetch langs from moodledata/lang directory
        $langdirs2 = get_list_of_plugins('lang', '', $CFG->dataroot);
    /// Merge both lists of langs
        $langdirs = array_merge($langdirs, $langdirs2);
    /// Sort all
        asort($langdirs);
    /// Get some info from each lang (first from moodledata, then from moodle)
        foreach ($langdirs as $lang) {
            if (strstr($lang, '_local')!==false) {
                continue;
            }
            if (substr($lang, -5) == '_utf8') {   //Remove the _utf8 suffix from the lang to show
                $shortlang = substr($lang, 0, -5);
            } else {
                $shortlang = $lang;
            }
        /// Search under moodledata/lang
            if (file_exists($CFG->dataroot .'/lang/'. $lang .'/'. $filetocheck)) {
                include($CFG->dataroot .'/lang/'. $lang .'/'. $filetocheck);
                if (!empty($string['thislanguage'])) {
                    $languages[$lang] = $string['thislanguage'] .' ('. $shortlang .')';
                }
                unset($string);
            }
        /// And dirroot/lang
            if (file_exists($CFG->dirroot .'/lang/'. $lang .'/'. $filetocheck)) {
                include($CFG->dirroot .'/lang/'. $lang .'/'. $filetocheck);
                if (!empty($string['thislanguage'])) {
                    $languages[$lang] = $string['thislanguage'] .' ('. $shortlang .')';
                }
                unset($string);
            }
        }
    }

    if ($refreshcache && !empty($CFG->langcache)) {
        if ($returnall) {
            // we have a list of all langs only, just delete old cache
            @unlink($CFG->dataroot.'/cache/languages');

        } else {
            // store the list of allowed languages
            if ($file = fopen($CFG->dataroot .'/cache/languages', 'w')) {
                foreach ($languages as $key => $value) {
                    fwrite($file, "$key $value\n");
                }
                fclose($file);
            }
        }
    }

    return $languages;
}

/**
 * Returns a list of charset codes. It's hardcoded, so they should be added manually
 * (cheking that such charset is supported by the texlib library!)
 *
 * @return array And associative array with contents in the form of charset => charset
 */
function get_list_of_charsets() {

    $charsets = array(
        'EUC-JP'     => 'EUC-JP',
        'ISO-2022-JP'=> 'ISO-2022-JP',
        'ISO-8859-1' => 'ISO-8859-1',
        'SHIFT-JIS'  => 'SHIFT-JIS',
        'GB2312'     => 'GB2312',
        'GB18030'    => 'GB18030', // gb18030 not supported by typo and mbstring
        'UTF-8'      => 'UTF-8');

    asort($charsets);

    return $charsets;
}

/**
 * Returns a list of country names in the current language
 *
 * @uses $CFG
 * @uses $USER
 * @return array
 */
function get_list_of_countries() {
    global $CFG, $USER;

    $lang = current_language();

    if (!file_exists($CFG->dirroot .'/lang/'. $lang .'/countries.php') &&
        !file_exists($CFG->dataroot.'/lang/'. $lang .'/countries.php')) {
        if ($parentlang = get_string('parentlanguage')) {
            if (file_exists($CFG->dirroot .'/lang/'. $parentlang .'/countries.php') ||
                file_exists($CFG->dataroot.'/lang/'. $parentlang .'/countries.php')) {
                $lang = $parentlang;
            } else {
                $lang = 'en_utf8';  // countries.php must exist in this pack
            }
        } else {
            $lang = 'en_utf8';  // countries.php must exist in this pack
        }
    }

    if (file_exists($CFG->dataroot .'/lang/'. $lang .'/countries.php')) {
        include($CFG->dataroot .'/lang/'. $lang .'/countries.php');
    } else if (file_exists($CFG->dirroot .'/lang/'. $lang .'/countries.php')) {
        include($CFG->dirroot .'/lang/'. $lang .'/countries.php');
    }

    if (!empty($string)) {
        asort($string);
    }

    return $string;
}

/**
 * Returns a list of valid and compatible themes
 *
 * @uses $CFG
 * @return array
 */
function get_list_of_themes() {

    global $CFG;

    $themes = array();

    if (!empty($CFG->themelist)) {       // use admin's list of themes
        $themelist = explode(',', $CFG->themelist);
    } else {
        $themelist = get_list_of_plugins("theme");
    }

    foreach ($themelist as $key => $theme) {
        if (!file_exists("$CFG->themedir/$theme/config.php")) {   // bad folder
            continue;
        }
        $THEME = new object();    // Note this is not the global one!!  :-)
        include("$CFG->themedir/$theme/config.php");
        if (!isset($THEME->sheets)) {   // Not a valid 1.5 theme
            continue;
        }
        $themes[$theme] = $theme;
    }
    asort($themes);

    return $themes;
}


/**
 * Returns a list of picture names in the current or specified language
 *
 * @uses $CFG
 * @return array
 */
function get_list_of_pixnames($lang = '') {
    global $CFG;

    if (empty($lang)) {
        $lang = current_language();
    }

    $string = array();

    $path = $CFG->dirroot .'/lang/en_utf8/pix.php'; // always exists

    if (file_exists($CFG->dataroot .'/lang/'. $lang .'_local/pix.php')) {
        $path = $CFG->dataroot .'/lang/'. $lang .'_local/pix.php';

    } else if (file_exists($CFG->dirroot .'/lang/'. $lang .'/pix.php')) {
        $path = $CFG->dirroot .'/lang/'. $lang .'/pix.php';

    } else if (file_exists($CFG->dataroot .'/lang/'. $lang .'/pix.php')) {
        $path = $CFG->dataroot .'/lang/'. $lang .'/pix.php';

    } else if ($parentlang = get_string('parentlanguage') and $parentlang != '[[parentlanguage]]') {
        return get_list_of_pixnames($parentlang); //return pixnames from parent language instead
    }

    include($path);

    return $string;
}

/**
 * Returns a list of timezones in the current language
 *
 * @uses $CFG
 * @return array
 */
function get_list_of_timezones() {
    global $CFG;

    static $timezones;

    if (!empty($timezones)) {    // This function has been called recently
        return $timezones;
    }

    $timezones = array();

    if ($rawtimezones = get_records_sql('SELECT MAX(id), name FROM '.$CFG->prefix.'timezone GROUP BY name')) {
        foreach($rawtimezones as $timezone) {
            if (!empty($timezone->name)) {
                $timezones[$timezone->name] = get_string(strtolower($timezone->name), 'timezones');
                if (substr($timezones[$timezone->name], 0, 1) == '[') {  // No translation found
                    $timezones[$timezone->name] = $timezone->name;
                }
            }
        }
    }

    asort($timezones);

    for ($i = -13; $i <= 13; $i += .5) {
        $tzstring = 'UTC';
        if ($i < 0) {
            $timezones[sprintf("%.1f", $i)] = $tzstring . $i;
        } else if ($i > 0) {
            $timezones[sprintf("%.1f", $i)] = $tzstring . '+' . $i;
        } else {
            $timezones[sprintf("%.1f", $i)] = $tzstring;
        }
    }

    return $timezones;
}

/**
 * Returns a list of currencies in the current language
 *
 * @uses $CFG
 * @uses $USER
 * @return array
 */
function get_list_of_currencies() {
    global $CFG, $USER;

    $lang = current_language();

    if (!file_exists($CFG->dataroot .'/lang/'. $lang .'/currencies.php')) {
        if ($parentlang = get_string('parentlanguage')) {
            if (file_exists($CFG->dataroot .'/lang/'. $parentlang .'/currencies.php')) {
                $lang = $parentlang;
            } else {
                $lang = 'en_utf8';  // currencies.php must exist in this pack
            }
        } else {
            $lang = 'en_utf8';  // currencies.php must exist in this pack
        }
    }

    if (file_exists($CFG->dataroot .'/lang/'. $lang .'/currencies.php')) {
        include_once($CFG->dataroot .'/lang/'. $lang .'/currencies.php');
    } else {    //if en_utf8 is not installed in dataroot
        include_once($CFG->dirroot .'/lang/'. $lang .'/currencies.php');
    }

    if (!empty($string)) {
        asort($string);
    }

    return $string;
}



/**
 * Can include a given document file (depends on second
 * parameter) or just return info about it.
 *
 * @uses $CFG
 * @param string $file ?
 * @param bool $include ?
 * @return ?
 * @todo Finish documenting this function
 */
function document_file($file, $include=true) {
    global $CFG;

    $file = clean_filename($file);

    if (empty($file)) {
        return false;
    }

    $langs = array(current_language(), get_string('parentlanguage'), 'en');

    foreach ($langs as $lang) {
        $info = new object();
        $info->filepath = $CFG->dirroot .'/lang/'. $lang .'/docs/'. $file;
        $info->urlpath  = $CFG->wwwroot .'/lang/'. $lang .'/docs/'. $file;

        if (file_exists($info->filepath)) {
            if ($include) {
                include($info->filepath);
            }
            return $info;
        }
    }

    return false;
}

/// ENCRYPTION  ////////////////////////////////////////////////

/**
 * rc4encrypt
 *
 * @param string $data ?
 * @return string
 * @todo Finish documenting this function
 */
function rc4encrypt($data) {
    $password = 'nfgjeingjk';
    return endecrypt($password, $data, '');
}

/**
 * rc4decrypt
 *
 * @param string $data ?
 * @return string
 * @todo Finish documenting this function
 */
function rc4decrypt($data) {
    $password = 'nfgjeingjk';
    return endecrypt($password, $data, 'de');
}

/**
 * Based on a class by Mukul Sabharwal [mukulsabharwal @ yahoo.com]
 *
 * @param string $pwd ?
 * @param string $data ?
 * @param string $case ?
 * @return string
 * @todo Finish documenting this function
 */
function endecrypt ($pwd, $data, $case) {

    if ($case == 'de') {
        $data = urldecode($data);
    }

    $key[] = '';
    $box[] = '';
    $temp_swap = '';
    $pwd_length = 0;

    $pwd_length = strlen($pwd);

    for ($i = 0; $i <= 255; $i++) {
        $key[$i] = ord(substr($pwd, ($i % $pwd_length), 1));
        $box[$i] = $i;
    }

    $x = 0;

    for ($i = 0; $i <= 255; $i++) {
        $x = ($x + $box[$i] + $key[$i]) % 256;
        $temp_swap = $box[$i];
        $box[$i] = $box[$x];
        $box[$x] = $temp_swap;
    }

    $temp = '';
    $k = '';

    $cipherby = '';
    $cipher = '';

    $a = 0;
    $j = 0;

    for ($i = 0; $i < strlen($data); $i++) {
        $a = ($a + 1) % 256;
        $j = ($j + $box[$a]) % 256;
        $temp = $box[$a];
        $box[$a] = $box[$j];
        $box[$j] = $temp;
        $k = $box[(($box[$a] + $box[$j]) % 256)];
        $cipherby = ord(substr($data, $i, 1)) ^ $k;
        $cipher .= chr($cipherby);
    }

    if ($case == 'de') {
        $cipher = urldecode(urlencode($cipher));
    } else {
        $cipher = urlencode($cipher);
    }

    return $cipher;
}


/// CALENDAR MANAGEMENT  ////////////////////////////////////////////////////////////////


/**
 * Call this function to add an event to the calendar table
 *  and to call any calendar plugins
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field. The object event should include the following:
 *  <ul>
 *    <li><b>$event->name</b> - Name for the event
 *    <li><b>$event->description</b> - Description of the event (defaults to '')
 *    <li><b>$event->format</b> - Format for the description (using formatting types defined at the top of weblib.php)
 *    <li><b>$event->courseid</b> - The id of the course this event belongs to (0 = all courses)
 *    <li><b>$event->groupid</b> - The id of the group this event belongs to (0 = no group)
 *    <li><b>$event->userid</b> - The id of the user this event belongs to (0 = no user)
 *    <li><b>$event->modulename</b> - Name of the module that creates this event
 *    <li><b>$event->instance</b> - Instance of the module that owns this event
 *    <li><b>$event->eventtype</b> - The type info together with the module info could
 *             be used by calendar plugins to decide how to display event
 *    <li><b>$event->timestart</b>- Timestamp for start of event
 *    <li><b>$event->timeduration</b> - Duration (defaults to zero)
 *    <li><b>$event->visible</b> - 0 if the event should be hidden (e.g. because the activity that created it is hidden)
 *  </ul>
 * @return int The id number of the resulting record
 */
 function add_event($event) {

    global $CFG;

    $event->timemodified = time();

    if (!$event->id = insert_record('event', $event)) {
        return false;
    }

    if (!empty($CFG->calendar)) { // call the add_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_add_event = $CFG->calendar.'_add_event';
            if (function_exists($calendar_add_event)) {
                $calendar_add_event($event);
            }
        }
    }

    return $event->id;
}

/**
 * Call this function to update an event in the calendar table
 * the event will be identified by the id field of the $event object.
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field.
 * @return bool
 */
function update_event($event) {

    global $CFG;

    $event->timemodified = time();

    if (!empty($CFG->calendar)) { // call the update_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_update_event = $CFG->calendar.'_update_event';
            if (function_exists($calendar_update_event)) {
                $calendar_update_event($event);
            }
        }
    }
    return update_record('event', $event);
}

/**
 * Call this function to delete the event with id $id from calendar table.
 *
 * @uses $CFG
 * @param int $id The id of an event from the 'calendar' table.
 * @return array An associative array with the results from the SQL call.
 * @todo Verify return type
 */
function delete_event($id) {

    global $CFG;

    if (!empty($CFG->calendar)) { // call the delete_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_delete_event = $CFG->calendar.'_delete_event';
            if (function_exists($calendar_delete_event)) {
                $calendar_delete_event($id);
            }
        }
    }
    return delete_records('event', 'id', $id);
}

/**
 * Call this function to hide an event in the calendar table
 * the event will be identified by the id field of the $event object.
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field.
 * @return array An associative array with the results from the SQL call.
 * @todo Verify return type
 */
function hide_event($event) {
    global $CFG;

    if (!empty($CFG->calendar)) { // call the update_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_hide_event = $CFG->calendar.'_hide_event';
            if (function_exists($calendar_hide_event)) {
                $calendar_hide_event($event);
            }
        }
    }
    return set_field('event', 'visible', 0, 'id', $event->id);
}

/**
 * Call this function to unhide an event in the calendar table
 * the event will be identified by the id field of the $event object.
 *
 * @uses $CFG
 * @param array $event An associative array representing an event from the calendar table. The event will be identified by the id field.
 * @return array An associative array with the results from the SQL call.
 * @todo Verify return type
 */
function show_event($event) {
    global $CFG;

    if (!empty($CFG->calendar)) { // call the update_event function of the selected calendar
        if (file_exists($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php')) {
            include_once($CFG->dirroot .'/calendar/'. $CFG->calendar .'/lib.php');
            $calendar_show_event = $CFG->calendar.'_show_event';
            if (function_exists($calendar_show_event)) {
                $calendar_show_event($event);
            }
        }
    }
    return set_field('event', 'visible', 1, 'id', $event->id);
}


/// ENVIRONMENT CHECKING  ////////////////////////////////////////////////////////////

/**
 * Lists plugin directories within some directory
 *
 * @uses $CFG
 * @param string $plugin dir under we'll look for plugins (defaults to 'mod')
 * @param string $exclude dir name to exclude from the list (defaults to none)
 * @param string $basedir full path to the base dir where $plugin resides (defaults to $CFG->dirroot)
 * @return array of plugins found under the requested parameters
 */
function get_list_of_plugins($plugin='mod', $exclude='', $basedir='') {

    global $CFG;

    $plugins = array();

    if (empty($basedir)) {

        # This switch allows us to use the appropiate theme directory - and potentialy alternatives for other plugins
        switch ($plugin) {
        case "theme":
            $basedir = $CFG->themedir;
            break;

        default:
            $basedir = $CFG->dirroot .'/'. $plugin;
        }

    } else {
        $basedir = $basedir .'/'. $plugin;
    }

    if (file_exists($basedir) && filetype($basedir) == 'dir') {
        $dirhandle = opendir($basedir);
        while (false !== ($dir = readdir($dirhandle))) {
            $firstchar = substr($dir, 0, 1);
            if ($firstchar == '.' or $dir == 'CVS' or $dir == '_vti_cnf' or $dir == $exclude) {
                continue;
            }
            if (filetype($basedir .'/'. $dir) != 'dir') {
                continue;
            }
            $plugins[] = $dir;
        }
        closedir($dirhandle);
    }
    if ($plugins) {
        asort($plugins);
    }
    return $plugins;
}

/**
 * Returns true if the current version of PHP is greater that the specified one.
 *
 * @param string $version The version of php being tested.
 * @return bool
 */
function check_php_version($version='4.1.0') {
    return (version_compare(phpversion(), $version) >= 0);
}


/**
 * Checks to see if is a browser matches the specified
 * brand and is equal or better version.
 *
 * @uses $_SERVER
 * @param string $brand The browser identifier being tested
 * @param int $version The version of the browser
 * @return bool true if the given version is below that of the detected browser
 */
 function check_browser_version($brand='MSIE', $version=5.5) {
    if (empty($_SERVER['HTTP_USER_AGENT'])) {
        return false;
    }

    $agent = $_SERVER['HTTP_USER_AGENT'];

    switch ($brand) {

      case 'Camino':   /// Mozilla Firefox browsers

              if (preg_match("/Camino\/([0-9\.]+)/i", $agent, $match)) {
                  if (version_compare($match[1], $version) >= 0) {
                      return true;
                  }
              }
              break;


      case 'Firefox':   /// Mozilla Firefox browsers

          if (preg_match("/Firefox\/([0-9\.]+)/i", $agent, $match)) {
              if (version_compare($match[1], $version) >= 0) {
                  return true;
              }
          }
          break;


      case 'Gecko':   /// Gecko based browsers

          if (substr_count($agent, 'Camino')) {
              // MacOS X Camino support
              $version = 20041110;
          }

          // the proper string - Gecko/CCYYMMDD Vendor/Version
          // Faster version and work-a-round No IDN problem.
          if (preg_match("/Gecko\/([0-9]+)/i", $agent, $match)) {
              if ($match[1] > $version) {
                      return true;
                  }
              }
          break;


      case 'MSIE':   /// Internet Explorer

          if (strpos($agent, 'Opera')) {     // Reject Opera
              return false;
          }
          $string = explode(';', $agent);
          if (!isset($string[1])) {
              return false;
          }
          $string = explode(' ', trim($string[1]));
          if (!isset($string[0]) and !isset($string[1])) {
              return false;
          }
          if ($string[0] == $brand and (float)$string[1] >= $version ) {
              return true;
          }
          break;

      case 'Opera':  /// Opera

          if (preg_match("/Opera\/([0-9\.]+)/i", $agent, $match)) {
              if (version_compare($match[1], $version) >= 0) {
                  return true;
              }
          }
          break;

      case 'Safari':  /// Safari
          // Look for AppleWebKit, excluding strings with OmniWeb, Shiira and SimbianOS
          if (strpos($agent, 'OmniWeb')) { // Reject OmniWeb
              return false;
          } elseif (strpos($agent, 'Shiira')) { // Reject Shiira
              return false;
          } elseif (strpos($agent, 'SimbianOS')) { // Reject SimbianOS
              return false;
          }

          if (preg_match("/AppleWebKit\/([0-9]+)/i", $agent, $match)) {
              if (version_compare($match[1], $version) >= 0) {
                  return true;
              }
          }

          break;

    }

    return false;
}

/**
 * This function makes the return value of ini_get consistent if you are
 * setting server directives through the .htaccess file in apache.
 * Current behavior for value set from php.ini On = 1, Off = [blank]
 * Current behavior for value set from .htaccess On = On, Off = Off
 * Contributed by jdell @ unr.edu
 *
 * @param string $ini_get_arg ?
 * @return bool
 * @todo Finish documenting this function
 */
function ini_get_bool($ini_get_arg) {
    $temp = ini_get($ini_get_arg);

    if ($temp == '1' or strtolower($temp) == 'on') {
        return true;
    }
    return false;
}

/**
 * Compatibility stub to provide backward compatibility
 *
 * Determines if the HTML editor is enabled.
 * @deprecated Use {@link can_use_html_editor()} instead.
 */
 function can_use_richtext_editor() {
    return can_use_html_editor();
}

/**
 * Determines if the HTML editor is enabled.
 *
 * This depends on site and user
 * settings, as well as the current browser being used.
 *
 * @return string|false Returns false if editor is not being used, otherwise
 * returns 'MSIE' or 'Gecko'.
 */
 function can_use_html_editor() {
    global $USER, $CFG;

    if (!empty($USER->htmleditor) and !empty($CFG->htmleditor)) {
        if (check_browser_version('MSIE', 5.5)) {
            return 'MSIE';
        } else if (check_browser_version('Gecko', 20030516)) {
            return 'Gecko';
        }
    }
    return false;
}

/**
 * Hack to find out the GD version by parsing phpinfo output
 *
 * @return int GD version (1, 2, or 0)
 */
function check_gd_version() {
    $gdversion = 0;

    if (function_exists('gd_info')){
        $gd_info = gd_info();
        if (substr_count($gd_info['GD Version'], '2.')) {
            $gdversion = 2;
        } else if (substr_count($gd_info['GD Version'], '1.')) {
            $gdversion = 1;
        }

    } else {
        ob_start();
        phpinfo(8);
        $phpinfo = ob_get_contents();
        ob_end_clean();

        $phpinfo = explode("\n", $phpinfo);


        foreach ($phpinfo as $text) {
            $parts = explode('</td>', $text);
            foreach ($parts as $key => $val) {
                $parts[$key] = trim(strip_tags($val));
            }
            if ($parts[0] == 'GD Version') {
                if (substr_count($parts[1], '2.0')) {
                    $parts[1] = '2.0';
                }
                $gdversion = intval($parts[1]);
            }
        }
    }

    return $gdversion;   // 1, 2 or 0
}

/**
 * Determine if moodle installation requires update
 *
 * Checks version numbers of main code and all modules to see
 * if there are any mismatches
 *
 * @uses $CFG
 * @return bool
 */
function moodle_needs_upgrading() {
    global $CFG;

    $version = null;
    include_once($CFG->dirroot .'/version.php');  # defines $version and upgrades
    if ($CFG->version) {
        if ($version > $CFG->version) {
            return true;
        }
        if ($mods = get_list_of_plugins('mod')) {
            foreach ($mods as $mod) {
                $fullmod = $CFG->dirroot .'/mod/'. $mod;
                $module = new object();
                if (!is_readable($fullmod .'/version.php')) {
                    notify('Module "'. $mod .'" is not readable - check permissions');
                    continue;
                }
                include_once($fullmod .'/version.php');  # defines $module with version etc
                if ($currmodule = get_record('modules', 'name', $mod)) {
                    if ($module->version > $currmodule->version) {
                        return true;
                    }
                }
            }
        }
    } else {
        return true;
    }
    return false;
}


/// MISCELLANEOUS ////////////////////////////////////////////////////////////////////

/**
 * Notify admin users or admin user of any failed logins (since last notification).
 *
 * @uses $CFG
 * @uses $db
 * @uses HOURSECS
 */
function notify_login_failures() {
    global $CFG, $db;

    switch ($CFG->notifyloginfailures) {
        case 'mainadmin' :
            $recip = array(get_admin());
            break;
        case 'alladmins':
            $recip = get_admins();
            break;
    }

    if (empty($CFG->lastnotifyfailure)) {
        $CFG->lastnotifyfailure=0;
    }

    // we need to deal with the threshold stuff first.
    if (empty($CFG->notifyloginthreshold)) {
        $CFG->notifyloginthreshold = 10; // default to something sensible.
    }

    $notifyipsrs = $db->Execute('SELECT ip FROM '. $CFG->prefix .'log WHERE time > '. $CFG->lastnotifyfailure .'
                          AND module=\'login\' AND action=\'error\' GROUP BY ip HAVING count(*) > '. $CFG->notifyloginthreshold);

    $notifyusersrs = $db->Execute('SELECT info FROM '. $CFG->prefix .'log WHERE time > '. $CFG->lastnotifyfailure .'
                          AND module=\'login\' AND action=\'error\' GROUP BY info HAVING count(*) > '. $CFG->notifyloginthreshold);

    if ($notifyipsrs) {
        $ipstr = '';
        while ($row = rs_fetch_next_record($notifyipsrs)) {
            $ipstr .= "'". $row->ip ."',";
        }
        rs_close($notifyipsrs);
        $ipstr = substr($ipstr,0,strlen($ipstr)-1);
    }
    if ($notifyusersrs) {
        $userstr = '';
        while ($row = rs_fetch_next_record($notifyusersrs)) {
            $userstr .= "'". $row->info ."',";
        }
        rs_close($notifyusersrs);
        $userstr = substr($userstr,0,strlen($userstr)-1);
    }

    if (strlen($userstr) > 0 || strlen($ipstr) > 0) {
        $count = 0;
        $logs = get_logs('time > '. $CFG->lastnotifyfailure .' AND module=\'login\' AND action=\'error\' '
                 .((strlen($ipstr) > 0 && strlen($userstr) > 0) ? ' AND ( ip IN ('. $ipstr .') OR info IN ('. $userstr .') ) '
                 : ((strlen($ipstr) != 0) ? ' AND ip IN ('. $ipstr .') ' : ' AND info IN ('. $userstr .') ')), 'l.time DESC', '', '', $count);

        // if we haven't run in the last hour and we have something useful to report and we are actually supposed to be reporting to somebody
        if (is_array($recip) and count($recip) > 0 and ((time() - HOURSECS) > $CFG->lastnotifyfailure)
            and is_array($logs) and count($logs) > 0) {

            $message = '';
            $site = get_site();
            $subject = get_string('notifyloginfailuressubject', '', format_string($site->fullname));
            $message .= get_string('notifyloginfailuresmessagestart', '', $CFG->wwwroot)
                 .(($CFG->lastnotifyfailure != 0) ? '('.userdate($CFG->lastnotifyfailure).')' : '')."\n\n";
            foreach ($logs as $log) {
                $log->time = userdate($log->time);
                $message .= get_string('notifyloginfailuresmessage','',$log)."\n";
            }
            $message .= "\n\n".get_string('notifyloginfailuresmessageend','',$CFG->wwwroot)."\n\n";
            foreach ($recip as $admin) {
                mtrace('Emailing '. $admin->username .' about '. count($logs) .' failed login attempts');
                email_to_user($admin,get_admin(),$subject,$message);
            }
            $conf = new object();
            $conf->name = 'lastnotifyfailure';
            $conf->value = time();
            if ($current = get_record('config', 'name', 'lastnotifyfailure')) {
                $conf->id = $current->id;
                if (! update_record('config', $conf)) {
                    mtrace('Could not update last notify time');
                }

            } else if (! insert_record('config', $conf)) {
                mtrace('Could not set last notify time');
            }
        }
    }
}

/**
 * moodle_setlocale
 *
 * @uses $CFG
 * @param string $locale ?
 * @todo Finish documenting this function
 */
function moodle_setlocale($locale='') {

    global $CFG;

    static $currentlocale = ''; // last locale caching

    $oldlocale = $currentlocale;

/// Fetch the correct locale based on ostype
    if($CFG->ostype == 'WINDOWS') {
        $stringtofetch = 'localewin';
    } else {
        $stringtofetch = 'locale';
    }

/// the priority is the same as in get_string() - parameter, config, course, session, user, global language
    if (!empty($locale)) {
        $currentlocale = $locale;
    } else if (!empty($CFG->locale)) { // override locale for all language packs
        $currentlocale = $CFG->locale;
    } else {
        $currentlocale = get_string($stringtofetch);
    }

/// do nothing if locale already set up
    if ($oldlocale == $currentlocale) {
        return;
    }

/// Due to some strange BUG we cannot set the LC_TIME directly, so we fetch current values,
/// set LC_ALL and then set values again. Just wondering why we cannot set LC_ALL only??? - stronk7
/// Some day, numeric, monetary and other categories should be set too, I think. :-/

/// Get current values
    $monetary= setlocale (LC_MONETARY, 0);
    $numeric = setlocale (LC_NUMERIC, 0);
    $ctype   = setlocale (LC_CTYPE, 0);
    if ($CFG->ostype != 'WINDOWS') {
        $messages= setlocale (LC_MESSAGES, 0);
    }
/// Set locale to all
    setlocale (LC_ALL, $currentlocale);
/// Set old values
    setlocale (LC_MONETARY, $monetary);
    setlocale (LC_NUMERIC, $numeric);
    if ($CFG->ostype != 'WINDOWS') {
        setlocale (LC_MESSAGES, $messages);
    }
    if ($currentlocale == 'tr_TR' or $currentlocale == 'tr_TR.UTF-8') { // To workaround a well-known PHP problem with Turkish letter Ii
        setlocale (LC_CTYPE, $ctype);
    }
}

/**
 * Converts string to lowercase using most compatible function available.
 *
 * @param string $string The string to convert to all lowercase characters.
 * @param string $encoding The encoding on the string.
 * @return string
 * @todo Add examples of calling this function with/without encoding types
 * @deprecated Use textlib->strtolower($text) instead.
 */
function moodle_strtolower ($string, $encoding='') {

    //If not specified use utf8
    if (empty($encoding)) {
        $encoding = 'UTF-8';
    }
    //Use text services
    $textlib = textlib_get_instance();

    return $textlib->strtolower($string, $encoding);
}

/**
 * Count words in a string.
 *
 * Words are defined as things between whitespace.
 *
 * @param string $string The text to be searched for words.
 * @return int The count of words in the specified string
 */
function count_words($string) {
    $string = strip_tags($string);
    return count(preg_split("/\w\b/", $string)) - 1;
}

/** Count letters in a string.
 *
 * Letters are defined as chars not in tags and different from whitespace.
 *
 * @param string $string The text to be searched for letters.
 * @return int The count of letters in the specified text.
 */
function count_letters($string) {
/// Loading the textlib singleton instance. We are going to need it.
    $textlib = textlib_get_instance();

    $string = strip_tags($string); // Tags are out now
    $string = ereg_replace('[[:space:]]*','',$string); //Whitespace are out now

    return $textlib->strlen($string);
}

/**
 * Generate and return a random string of the specified length.
 *
 * @param int $length The length of the string to be created.
 * @return string
 */
function random_string ($length=15) {
    $pool  = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $pool .= 'abcdefghijklmnopqrstuvwxyz';
    $pool .= '0123456789';
    $poollen = strlen($pool);
    mt_srand ((double) microtime() * 1000000);
    $string = '';
    for ($i = 0; $i < $length; $i++) {
        $string .= substr($pool, (mt_rand()%($poollen)), 1);
    }
    return $string;
}

/*
 * Given some text (which may contain HTML) and an ideal length,
 * this function truncates the text neatly on a word boundary if possible
 * @param string $text - text to be shortened
 * @param int $ideal - ideal string length
 * @param boolean $exact if false, $text will not be cut mid-word
 * @return string $truncate - shortened string 
 */

function shorten_text($text, $ideal=30, $exact = false) {

    global $CFG;
    $ending = '...';

    // if the plain text is shorter than the maximum length, return the whole text
    if (strlen(preg_replace('/<.*?>/', '', $text)) <= $ideal) {
        return $text;
    }
            
    // splits all html-tags to scanable lines
    preg_match_all('/(<.+?>)?([^<>]*)/s', $text, $lines, PREG_SET_ORDER);

    $total_length = strlen($ending);
    $open_tags = array();
    $truncate = '';

    foreach ($lines as $line_matchings) {
        // if there is any html-tag in this line, handle it and add it (uncounted) to the output
        if (!empty($line_matchings[1])) {
            // if it's an "empty element" with or without xhtml-conform closing slash (f.e. <br/>)
            if (preg_match('/^<(\s*.+?\/\s*|\s*(img|br|input|hr|area|base|basefont|col|frame|isindex|link|meta|param)(\s.+?)?)>$/is', $line_matchings[1])) {
                    // do nothing
            // if tag is a closing tag (f.e. </b>)
            } else if (preg_match('/^<\s*\/([^\s]+?)\s*>$/s', $line_matchings[1], $tag_matchings)) {
                // delete tag from $open_tags list
                $pos = array_search($tag_matchings[1], array_reverse($open_tags, true)); // can have multiple exact same open tags, close the last one
                if ($pos !== false) {
                    unset($open_tags[$pos]);
                }
            // if tag is an opening tag (f.e. <b>)
            } else if (preg_match('/^<\s*([^\s>!]+).*?>$/s', $line_matchings[1], $tag_matchings)) {
                // add tag to the beginning of $open_tags list
                array_unshift($open_tags, strtolower($tag_matchings[1]));
            }
            // add html-tag to $truncate'd text
            $truncate .= $line_matchings[1];
        }

        // calculate the length of the plain text part of the line; handle entities as one character
        $content_length = strlen(preg_replace('/&[0-9a-z]{2,8};|&#[0-9]{1,7};|&#x[0-9a-f]{1,6};/i', ' ', $line_matchings[2]));
        if ($total_length+$content_length > $ideal) {
            // the number of characters which are left
            $left = $ideal - $total_length;
            $entities_length = 0;
            // search for html entities
            if (preg_match_all('/&[0-9a-z]{2,8};|&#[0-9]{1,7};|&#x[0-9a-f]{1,6};/i', $line_matchings[2], $entities, PREG_OFFSET_CAPTURE)) {
                // calculate the real length of all entities in the legal range
                foreach ($entities[0] as $entity) {
                    if ($entity[1]+1-$entities_length <= $left) {
                        $left--;
                        $entities_length += strlen($entity[0]);
                    } else {
                        // no more characters left
                        break;
                    }
                }
            }
            $truncate .= substr($line_matchings[2], 0, $left+$entities_length);
            // maximum lenght is reached, so get off the loop
            break;
        } else {
            $truncate .= $line_matchings[2];
            $total_length += $content_length;
        }
                
        // if the maximum length is reached, get off the loop
        if($total_length >= $ideal) {
            break;
        }
    }

    // if the words shouldn't be cut in the middle...
    if (!$exact) {
        // ...search the last occurance of a space...
		for ($k=strlen($truncate);$k>0;$k--) {
            if (!empty($truncate[$k]) && ($char = $truncate[$k])) {
                if ($char == '.' or $char == ' ') {
                    $breakpos = $k+1;
                    break;
                } else if (ord($char) >= 0xE0) {  // Chinese/Japanese/Korean text
                    $breakpos = $k;               // can be truncated at any UTF-8
                    break;                        // character boundary.
                }
            }
		}
        
		if (isset($breakpos)) {
            // ...and cut the text in this position
            $truncate = substr($truncate, 0, $breakpos);
		}
	}

    // add the defined ending to the text
	$truncate .= $ending;

    // close all unclosed html-tags
    foreach ($open_tags as $tag) {
        $truncate .= '</' . $tag . '>';
    }

	return $truncate;
}


/**
 * Given dates in seconds, how many weeks is the date from startdate
 * The first week is 1, the second 2 etc ...
 *
 * @uses WEEKSECS
 * @param ? $startdate ?
 * @param ? $thedate ?
 * @return string
 * @todo Finish documenting this function
 */
function getweek ($startdate, $thedate) {
    if ($thedate < $startdate) {   // error
        return 0;
    }

    return floor(($thedate - $startdate) / WEEKSECS) + 1;
}

/**
 * returns a randomly generated password of length $maxlen.  inspired by
 * {@link http://www.phpbuilder.com/columns/jesus19990502.php3}
 *
 * @param int $maxlength  The maximum size of the password being generated.
 * @return string
 */
function generate_password($maxlen=10) {
    global $CFG;

    $fillers = '1234567890!$-+';
    $wordlist = file($CFG->wordlist);

    srand((double) microtime() * 1000000);
    $word1 = trim($wordlist[rand(0, count($wordlist) - 1)]);
    $word2 = trim($wordlist[rand(0, count($wordlist) - 1)]);
    $filler1 = $fillers[rand(0, strlen($fillers) - 1)];

    return substr($word1 . $filler1 . $word2, 0, $maxlen);
}

/**
 * Given a float, prints it nicely
 *
 * @param float $num The float to print
 * @param int $places The number of decimal places to print.
 * @return string
 */
function format_float($num, $places=1) {
    return sprintf("%.$places"."f", $num);
}

/**
 * Given a simple array, this shuffles it up just like shuffle()
 * Unlike PHP's shuffle() ihis function works on any machine.
 *
 * @param array $array The array to be rearranged
 * @return array
 */
function swapshuffle($array) {

    srand ((double) microtime() * 10000000);
    $last = count($array) - 1;
    for ($i=0;$i<=$last;$i++) {
        $from = rand(0,$last);
        $curr = $array[$i];
        $array[$i] = $array[$from];
        $array[$from] = $curr;
    }
    return $array;
}

/**
 * Like {@link swapshuffle()}, but works on associative arrays
 *
 * @param array $array The associative array to be rearranged
 * @return array
 */
function swapshuffle_assoc($array) {
///

    $newkeys = swapshuffle(array_keys($array));
    foreach ($newkeys as $newkey) {
        $newarray[$newkey] = $array[$newkey];
    }
    return $newarray;
}

/**
 * Given an arbitrary array, and a number of draws,
 * this function returns an array with that amount
 * of items.  The indexes are retained.
 *
 * @param array $array ?
 * @param ? $draws ?
 * @return ?
 * @todo Finish documenting this function
 */
function draw_rand_array($array, $draws) {
    srand ((double) microtime() * 10000000);

    $return = array();

    $last = count($array);

    if ($draws > $last) {
        $draws = $last;
    }

    while ($draws > 0) {
        $last--;

        $keys = array_keys($array);
        $rand = rand(0, $last);

        $return[$keys[$rand]] = $array[$keys[$rand]];
        unset($array[$keys[$rand]]);

        $draws--;
    }

    return $return;
}

/**
 * microtime_diff
 *
 * @param string $a ?
 * @param string $b ?
 * @return string
 * @todo Finish documenting this function
 */
function microtime_diff($a, $b) {
    list($a_dec, $a_sec) = explode(' ', $a);
    list($b_dec, $b_sec) = explode(' ', $b);
    return $b_sec - $a_sec + $b_dec - $a_dec;
}

/**
 * Given a list (eg a,b,c,d,e) this function returns
 * an array of 1->a, 2->b, 3->c etc
 *
 * @param array $list ?
 * @param string $separator ?
 * @todo Finish documenting this function
 */
function make_menu_from_list($list, $separator=',') {

    $array = array_reverse(explode($separator, $list), true);
    foreach ($array as $key => $item) {
        $outarray[$key+1] = trim($item);
    }
    return $outarray;
}

/**
 * Creates an array that represents all the current grades that
 * can be chosen using the given grading type.  Negative numbers
 * are scales, zero is no grade, and positive numbers are maximum
 * grades.
 *
 * @param int $gradingtype ?
 * return int
 * @todo Finish documenting this function
 */
function make_grades_menu($gradingtype) {
    $grades = array();
    if ($gradingtype < 0) {
        if ($scale = get_record('scale', 'id', - $gradingtype)) {
            return make_menu_from_list($scale->scale);
        }
    } else if ($gradingtype > 0) {
        for ($i=$gradingtype; $i>=0; $i--) {
            $grades[$i] = $i .' / '. $gradingtype;
        }
        return $grades;
    }
    return $grades;
}

/**
 * Returns true if a scale is in use in the given course.
 *
 * @param int $courseid The course to be checked.
 * @param int $scaleid The scale to be checked.
 * @return boolean
 * @todo Finish documenting this function
 */
function course_scale_used($courseid, $scaleid) {

    global $CFG;

    $return = 0;

    if (!empty($scaleid)) {
        if ($cms = get_course_mods($courseid)) {
            foreach ($cms as $cm) {
                //Check cm->name/lib.php exists
                if (file_exists($CFG->dirroot.'/mod/'.$cm->modname.'/lib.php')) {
                    include_once($CFG->dirroot.'/mod/'.$cm->modname.'/lib.php');
                    $function_name = $cm->modname.'_scale_used';
                    if (function_exists($function_name)) {
                        if ($function_name($cm->instance,$scaleid)) {
                            return true;
                        }
                    }
                }
            }
        }
    }
    return false;
}

/**
 * Returns true if a scale is in use anywhere on the site.
 *
 * @param int $scaleid The scale to be checked.
 * @param array $courses The site courses, needed is the old way to check has to be used.
 * @return boolean
 */
function site_scale_used($scaleid,&$courses) {

    if (empty($scaleid)) {
        return false;
    }

    global $CFG;

    $return = 0;

    $legacy_mods = false;
    if ($mods = get_records('modules', 'visible', 1)) {
        foreach ($mods as $mod) {
            //Check $mod->name/lib.php exists
            if (file_exists($CFG->dirroot.'/mod/'.$mod->name.'/lib.php')) {
                include_once($CFG->dirroot.'/mod/'.$mod->name.'/lib.php');
                $function_name = $mod->name.'_scale_used_anywhere';
                $old_function_name = $mod->name.'_scale_used';
                if (function_exists($function_name)) {
                    if ($function_name($scaleid)) {
                        return true;
                    }
                } else if (function_exists($old_function_name)) {
                    $legacy_mods = true;
                    debugging('Please notify the developer of module "'.$mod->name.'" that new function module_scale_used_anywhere() should be implemented.', DEBUG_DEVELOPER);
                    break;
                }
            }
        }
    }

    // some mods are missing the new xxx_scale_used_anywhere() - use the really slow old way
    if ($legacy_mods) {
        if (!is_array($courses) || count($courses) == 0) {
            $courses = get_courses("all",false,"c.id,c.shortname");
        }
        if (is_array($courses) && count($courses) > 0) {
            foreach ($courses as $course) {
                if (course_scale_used($course->id,$scaleid)) {
                    return true;
                }
            }
        }
    }

    return false;
}

/**
 * make_unique_id_code
 *
 * @param string $extra ?
 * @return string
 * @todo Finish documenting this function
 */
function make_unique_id_code($extra='') {

    $hostname = 'unknownhost';
    if (!empty($_SERVER['HTTP_HOST'])) {
        $hostname = $_SERVER['HTTP_HOST'];
    } else if (!empty($_ENV['HTTP_HOST'])) {
        $hostname = $_ENV['HTTP_HOST'];
    } else if (!empty($_SERVER['SERVER_NAME'])) {
        $hostname = $_SERVER['SERVER_NAME'];
    } else if (!empty($_ENV['SERVER_NAME'])) {
        $hostname = $_ENV['SERVER_NAME'];
    }

    $date = gmdate("ymdHis");

    $random =  random_string(6);

    if ($extra) {
        return $hostname .'+'. $date .'+'. $random .'+'. $extra;
    } else {
        return $hostname .'+'. $date .'+'. $random;
    }
}


/**
 * Function to check the passed address is within the passed subnet
 *
 * The parameter is a comma separated string of subnet definitions.
 * Subnet strings can be in one of three formats:
 *   1: xxx.xxx.xxx.xxx/xx
 *   2: xxx.xxx
 *   3: xxx.xxx.xxx.xxx-xxx   //a range of IP addresses in the last group.
 * Code for type 1 modified from user posted comments by mediator at
 * {@link http://au.php.net/manual/en/function.ip2long.php}
 *
 * @param string $addr    The address you are checking
 * @param string $subnetstr    The string of subnet addresses
 * @return bool
 */
function address_in_subnet($addr, $subnetstr) {

    $subnets = explode(',', $subnetstr);
    $found = false;
    $addr = trim($addr);

    foreach ($subnets as $subnet) {
        $subnet = trim($subnet);
        if (strpos($subnet, '/') !== false) { /// type 1
            list($ip, $mask) = explode('/', $subnet);
            $mask = 0xffffffff << (32 - $mask);
            $found = ((ip2long($addr) & $mask) == (ip2long($ip) & $mask));
        } else if (strpos($subnet, '-') !== false)  {/// type 3
            $subnetparts = explode('.', $subnet);
            $addrparts = explode('.', $addr);
            $subnetrange = explode('-', array_pop($subnetparts));
            if (count($subnetrange) == 2) {
                $lastaddrpart = array_pop($addrparts);
                $found = ($subnetparts == $addrparts &&
                        $subnetrange[0] <= $lastaddrpart && $lastaddrpart <= $subnetrange[1]);
            }
        } else { /// type 2
            $found = (strpos($addr, $subnet) === 0);
        }

        if ($found) {
            break;
        }
    }
    return $found;
}

/**
 * This function sets the $HTTPSPAGEREQUIRED global
 * (used in some parts of moodle to change some links)
 * and calculate the proper wwwroot to be used
 *
 * By using this function properly, we can ensure 100% https-ized pages
 * at our entire discretion (login, forgot_password, change_password)
 */
function httpsrequired() {

    global $CFG, $HTTPSPAGEREQUIRED;

    if (!empty($CFG->loginhttps)) {
        $HTTPSPAGEREQUIRED = true;
        $CFG->httpswwwroot = str_replace('http:', 'https:', $CFG->wwwroot);
        $CFG->httpsthemewww = str_replace('http:', 'https:', $CFG->themewww);

        // change theme URLs to https
        theme_setup();

    } else {
        $CFG->httpswwwroot = $CFG->wwwroot;
        $CFG->httpsthemewww = $CFG->themewww;
    }
}

/**
 * For outputting debugging info
 *
 * @uses STDOUT
 * @param string $string ?
 * @param string $eol ?
 * @todo Finish documenting this function
 */
function mtrace($string, $eol="\n", $sleep=0) {

    if (defined('STDOUT')) {
        fwrite(STDOUT, $string.$eol);
    } else {
        echo $string . $eol;
    }

    flush();

    //delay to keep message on user's screen in case of subsequent redirect
    if ($sleep) {
        sleep($sleep);
    }
}

//Replace 1 or more slashes or backslashes to 1 slash
function cleardoubleslashes ($path) {
    return preg_replace('/(\/|\\\){1,}/','/',$path);
}

function zip_files ($originalfiles, $destination) {
//Zip an array of files/dirs to a destination zip file
//Both parameters must be FULL paths to the files/dirs

    global $CFG;

    //Extract everything from destination
    $path_parts = pathinfo(cleardoubleslashes($destination));
    $destpath = $path_parts["dirname"];       //The path of the zip file
    $destfilename = $path_parts["basename"];  //The name of the zip file
    $extension = $path_parts["extension"];    //The extension of the file

    //If no file, error
    if (empty($destfilename)) {
        return false;
    }

    //If no extension, add it
    if (empty($extension)) {
        $extension = 'zip';
        $destfilename = $destfilename.'.'.$extension;
    }

    //Check destination path exists
    if (!is_dir($destpath)) {
        return false;
    }

    //Check destination path is writable. TODO!!

    //Clean destination filename
    $destfilename = clean_filename($destfilename);

    //Now check and prepare every file
    $files = array();
    $origpath = NULL;

    foreach ($originalfiles as $file) {  //Iterate over each file
        //Check for every file
        $tempfile = cleardoubleslashes($file); // no doubleslashes!
        //Calculate the base path for all files if it isn't set
        if ($origpath === NULL) {
            $origpath = rtrim(cleardoubleslashes(dirname($tempfile)), "/");
        }
        //See if the file is readable
        if (!is_readable($tempfile)) {  //Is readable
            continue;
        }
        //See if the file/dir is in the same directory than the rest
        if (rtrim(cleardoubleslashes(dirname($tempfile)), "/") != $origpath) {
            continue;
        }
        //Add the file to the array
        $files[] = $tempfile;
    }

    //Everything is ready:
    //    -$origpath is the path where ALL the files to be compressed reside (dir).
    //    -$destpath is the destination path where the zip file will go (dir).
    //    -$files is an array of files/dirs to compress (fullpath)
    //    -$destfilename is the name of the zip file (without path)

    //print_object($files);                  //Debug

    if (empty($CFG->zip)) {    // Use built-in php-based zip function

        include_once("$CFG->libdir/pclzip/pclzip.lib.php");
        //rewrite filenames because the old method with PCLZIP_OPT_REMOVE_PATH does not work under win32
        $zipfiles = array();
        $start = strlen($origpath)+1;
        foreach($files as $file) {
            $tf = array();
            $tf[PCLZIP_ATT_FILE_NAME] = $file;
            $tf[PCLZIP_ATT_FILE_NEW_FULL_NAME] = substr($file, $start);
            $zipfiles[] = $tf;
        }
        //create the archive
        $archive = new PclZip(cleardoubleslashes("$destpath/$destfilename"));
        if (($list = $archive->create($zipfiles) == 0)) {
            notice($archive->errorInfo(true));
            return false;
        }

    } else {                   // Use external zip program

        $filestozip = "";
        foreach ($files as $filetozip) {
            $filestozip .= escapeshellarg(basename($filetozip));
            $filestozip .= " ";
        }
        //Construct the command
        $separator = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' ? ' &' : ' ;';
        $command = 'cd '.escapeshellarg($origpath).$separator.
                    escapeshellarg($CFG->zip).' -r '.
                    escapeshellarg(cleardoubleslashes("$destpath/$destfilename")).' '.$filestozip;
        //All converted to backslashes in WIN
        if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
            $command = str_replace('/','\\',$command);
        }
        Exec($command);
    }
    return true;
}

function unzip_file ($zipfile, $destination = '', $showstatus = true) {
//Unzip one zip file to a destination dir
//Both parameters must be FULL paths
//If destination isn't specified, it will be the
//SAME directory where the zip file resides.

    global $CFG;

    //Extract everything from zipfile
    $path_parts = pathinfo(cleardoubleslashes($zipfile));
    $zippath = $path_parts["dirname"];       //The path of the zip file
    $zipfilename = $path_parts["basename"];  //The name of the zip file
    $extension = $path_parts["extension"];    //The extension of the file

    //If no file, error
    if (empty($zipfilename)) {
        return false;
    }

    //If no extension, error
    if (empty($extension)) {
        return false;
    }

    //Clear $zipfile
    $zipfile = cleardoubleslashes($zipfile);

    //Check zipfile exists
    if (!file_exists($zipfile)) {
        return false;
    }

    //If no destination, passed let's go with the same directory
    if (empty($destination)) {
        $destination = $zippath;
    }

    //Clear $destination
    $destpath = rtrim(cleardoubleslashes($destination), "/");

    //Check destination path exists
    if (!is_dir($destpath)) {
        return false;
    }

    //Check destination path is writable. TODO!!

    //Everything is ready:
    //    -$zippath is the path where the zip file resides (dir)
    //    -$zipfilename is the name of the zip file (without path)
    //    -$destpath is the destination path where the zip file will uncompressed (dir)

    $list = null;

    if (empty($CFG->unzip)) {    // Use built-in php-based unzip function

        include_once("$CFG->libdir/pclzip/pclzip.lib.php");
        $archive = new PclZip(cleardoubleslashes("$zippath/$zipfilename"));
        if (!$list = $archive->extract(PCLZIP_OPT_PATH, $destpath,
                                       PCLZIP_CB_PRE_EXTRACT, 'unzip_cleanfilename',
                                       PCLZIP_OPT_EXTRACT_DIR_RESTRICTION, $destpath)) {
            notice($archive->errorInfo(true));
            return false;
        }

    } else {                     // Use external unzip program

        $separator = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' ? ' &' : ' ;';
        $redirection = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN' ? '' : ' 2>&1';

        $command = 'cd '.escapeshellarg($zippath).$separator.
                    escapeshellarg($CFG->unzip).' -o '.
                    escapeshellarg(cleardoubleslashes("$zippath/$zipfilename")).' -d '.
                    escapeshellarg($destpath).$redirection;
        //All converted to backslashes in WIN
        if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
            $command = str_replace('/','\\',$command);
        }
        Exec($command,$list);
    }

    //Display some info about the unzip execution
    if ($showstatus) {
        unzip_show_status($list,$destpath);
    }

    return true;
}

function unzip_cleanfilename ($p_event, &$p_header) {
//This function is used as callback in unzip_file() function
//to clean illegal characters for given platform and to prevent directory traversal.
//Produces the same result as info-zip unzip.
    $p_header['filename'] = ereg_replace('[[:cntrl:]]', '', $p_header['filename']); //strip control chars first!
    $p_header['filename'] = ereg_replace('\.\.+', '', $p_header['filename']); //directory traversal protection
    if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
        $p_header['filename'] = ereg_replace('[:*"?<>|]', '_', $p_header['filename']); //replace illegal chars
        $p_header['filename'] = ereg_replace('^([a-zA-Z])_', '\1:', $p_header['filename']); //repair drive letter
    } else {
        //Add filtering for other systems here
        // BSD: none (tested)
        // Linux: ??
        // MacosX: ??
    }
    $p_header['filename'] = cleardoubleslashes($p_header['filename']); //normalize the slashes/backslashes
    return 1;
}

function unzip_show_status ($list,$removepath) {
//This function shows the results of the unzip execution
//depending of the value of the $CFG->zip, results will be
//text or an array of files.

    global $CFG;

    if (empty($CFG->unzip)) {    // Use built-in php-based zip function
        $strname = get_string("name");
        $strsize = get_string("size");
        $strmodified = get_string("modified");
        $strstatus = get_string("status");
        echo "<table width=\"640\">";
        echo "<tr><th class=\"header\" scope=\"col\">$strname</th>";
        echo "<th class=\"header\" align=\"right\" scope=\"col\">$strsize</th>";
        echo "<th class=\"header\" align=\"right\" scope=\"col\">$strmodified</th>";
        echo "<th class=\"header\" align=\"right\" scope=\"col\">$strstatus</th></tr>";
        foreach ($list as $item) {
            echo "<tr>";
            $item['filename'] = str_replace(cleardoubleslashes($removepath).'/', "", $item['filename']);
            print_cell("left", s($item['filename']));
            if (! $item['folder']) {
                print_cell("right", display_size($item['size']));
            } else {
                echo "<td>&nbsp;</td>";
            }
            $filedate  = userdate($item['mtime'], get_string("strftimedatetime"));
            print_cell("right", $filedate);
            print_cell("right", $item['status']);
            echo "</tr>";
        }
        echo "</table>";

    } else {                   // Use external zip program
        print_simple_box_start("center");
        echo "<pre>";
        foreach ($list as $item) {
            echo s(str_replace(cleardoubleslashes($removepath.'/'), '', $item)).'<br />';
        }
        echo "</pre>";
        print_simple_box_end();
    }
}

/**
 * Returns most reliable client address
 *
 * @return string The remote IP address
 */
 function getremoteaddr() {
    if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
        return cleanremoteaddr($_SERVER['HTTP_CLIENT_IP']);
    }
    if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        return cleanremoteaddr($_SERVER['HTTP_X_FORWARDED_FOR']);
    }
    if (!empty($_SERVER['REMOTE_ADDR'])) {
        return cleanremoteaddr($_SERVER['REMOTE_ADDR']);
    }
    return '';
}

/**
 * Cleans a remote address ready to put into the log table
 */
function cleanremoteaddr($addr) {
    $originaladdr = $addr;
    $matches = array();
    // first get all things that look like IP addresses.
    if (!preg_match_all('/(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/',$addr,$matches,PREG_SET_ORDER)) {
        return '';
    }
    $goodmatches = array();
    $lanmatches = array();
    foreach ($matches as $match) {
        //        print_r($match);
        // check to make sure it's not an internal address.
        // the following are reserved for private lans...
        // 10.0.0.0 - 10.255.255.255
        // 172.16.0.0 - 172.31.255.255
        // 192.168.0.0 - 192.168.255.255
        // 169.254.0.0 -169.254.255.255
        $bits = explode('.',$match[0]);
        if (count($bits) != 4) {
            // weird, preg match shouldn't give us it.
            continue;
        }
        if (($bits[0] == 10)
            || ($bits[0] == 172 && $bits[1] >= 16 && $bits[1] <= 31)
            || ($bits[0] == 192 && $bits[1] == 168)
            || ($bits[0] == 169 && $bits[1] == 254)) {
            $lanmatches[] = $match[0];
            continue;
        }
        // finally, it's ok
        $goodmatches[] = $match[0];
    }
    if (!count($goodmatches)) {
        // perhaps we have a lan match, it's probably better to return that.
        if (!count($lanmatches)) {
            return '';
        } else {
            return array_pop($lanmatches);
        }
    }
    if (count($goodmatches) == 1) {
        return $goodmatches[0];
    }
    error_log("NOTICE: cleanremoteaddr gives us something funny: $originaladdr had ".count($goodmatches)." matches");
    // we need to return something, so
    return array_pop($goodmatches);
}

/**
 * file_put_contents is only supported by php 5.0 and higher
 * so if it is not predefined, define it here
 *
 * @param $file full path of the file to write
 * @param $contents contents to be sent
 * @return number of bytes written (false on error)
 */
if(!function_exists('file_put_contents')) {
    function file_put_contents($file, $contents) {
        $result = false;
        if ($f = fopen($file, 'w')) {
            $result = fwrite($f, $contents);
            fclose($f);
        }
        return $result;
    }
}

/**
 * The clone keyword is only supported from PHP 5 onwards.
 * The behaviour of $obj2 = $obj1 differs fundamentally
 * between PHP 4 and PHP 5. In PHP 4 a copy of $obj1 was
 * created, in PHP 5 $obj1 is referenced. To create a copy
 * in PHP 5 the clone keyword was introduced. This function
 * simulates this behaviour for PHP < 5.0.0.
 * See also: http://mjtsai.com/blog/2004/07/15/php-5-object-references/
 *
 * Modified 2005-09-29 by Eloy (from Julian Sedding proposal)
 * Found a better implementation (more checks and possibilities) from PEAR:
 * http://cvs.php.net/co.php/pear/PHP_Compat/Compat/Function/clone.php
 *
 * @param object $obj
 * @return object
 */
if(!check_php_version('5.0.0')) {
// the eval is needed to prevent PHP 5 from getting a parse error!
eval('
    function clone($obj) {
    /// Sanity check
        if (!is_object($obj)) {
            user_error(\'clone() __clone method called on non-object\', E_USER_WARNING);
            return;
        }

    /// Use serialize/unserialize trick to deep copy the object
        $obj = unserialize(serialize($obj));

    /// If there is a __clone method call it on the "new" class
        if (method_exists($obj, \'__clone\')) {
            $obj->__clone();
        }

        return $obj;
    }

    // Supply the PHP5 function scandir() to older versions.
    function scandir($directory) {
        $files = array();
        if ($dh = opendir($directory)) {
            while (($file = readdir($dh)) !== false) {
               $files[] = $file;
            }
            closedir($dh);
        }
        return $files;
    }

    // Supply the PHP5 function array_combine() to older versions.
    function array_combine($keys, $values) {
        if (!is_array($keys) || !is_array($values) || count($keys) != count($values)) {
            return false;
        }
        reset($values);
        $result = array();
        foreach ($keys as $key) {
            $result[$key] = current($values);
            next($values);
        }
        return $result;
    }
');
}

/**
 * This function will make a complete copy of anything it's given,
 * regardless of whether it's an object or not.
 * @param mixed $thing
 * @return mixed
 */
function fullclone($thing) {
    return unserialize(serialize($thing));
}


/*
 * This function expects to called during shutdown
 * should be set via register_shutdown_function()
 * in lib/setup.php .
 *
 * Right now we do it only if we are under apache, to
 * make sure apache children that hog too much mem are
 * killed.
 *
 */
function moodle_request_shutdown() {

    global $CFG;

    // initially, we are only ever called under apache
    // but check just in case
    if (function_exists('apache_child_terminate')
        && function_exists('memory_get_usage')
        && ini_get_bool('child_terminate')) {
        if (empty($CFG->apachemaxmem)) {
            $CFG->apachemaxmem = 25000000; // default 25MiB
        }
        if (memory_get_usage() > (int)$CFG->apachemaxmem) {
            trigger_error('Mem usage over $CFG->apachemaxmem: marking child for reaping.');
            @apache_child_terminate();
        }
    }
    if (defined('MDL_PERF') || (!empty($CFG->perfdebug) and $CFG->perfdebug > 7)) {
        if (defined('MDL_PERFTOLOG')) {
            $perf = get_performance_info();
            error_log("PERF: " . $perf['txt']);
        }
    }
}

/**
 * If new messages are waiting for the current user, then return
 * Javascript code to create a popup window
 *
 * @return string Javascript code
 */
function message_popup_window() {
    global $USER;

    $popuplimit = 30;     // Minimum seconds between popups

    if (!defined('MESSAGE_WINDOW')) {
        if (isset($USER->id)) {
            if (!isset($USER->message_lastpopup)) {
                $USER->message_lastpopup = 0;
            }
            if ((time() - $USER->message_lastpopup) > $popuplimit) {  /// It's been long enough
                if (get_user_preferences('message_showmessagewindow', 1) == 1) {
                    if (count_records_select('message', 'useridto = \''.$USER->id.'\' AND timecreated > \''.$USER->message_lastpopup.'\'')) {
                        $USER->message_lastpopup = time();
                        return '<script type="text/javascript">'."\n//<![CDATA[\n openpopup('/message/index.php', 'message',
                        'menubar=0,location=0,scrollbars,status,resizable,width=400,height=500', 0);\n//]]>\n</script>";
                    }
                }
            }
        }
    }

    return '';
}

// Used to make sure that $min <= $value <= $max
function bounded_number($min, $value, $max) {
    if($value < $min) {
        return $min;
    }
    if($value > $max) {
        return $max;
    }
    return $value;
}

function array_is_nested($array) {
    foreach ($array as $value) {
        if (is_array($value)) {
            return true;
        }
    }
    return false;
}

/**
 *** get_performance_info() pairs up with init_performance_info()
 *** loaded in setup.php. Returns an array with 'html' and 'txt'
 *** values ready for use, and each of the individual stats provided
 *** separately as well.
 ***
 **/
function get_performance_info() {
    global $CFG, $PERF, $rcache;

    $info = array();
    $info['html'] = '';         // holds userfriendly HTML representation
    $info['txt']  = me() . ' '; // holds log-friendly representation

    $info['realtime'] = microtime_diff($PERF->starttime, microtime());

    $info['html'] .= '<span class="timeused">'.$info['realtime'].' secs</span> ';
    $info['txt'] .= 'time: '.$info['realtime'].'s ';

    if (function_exists('memory_get_usage')) {
        $info['memory_total'] = memory_get_usage();
        $info['memory_growth'] = memory_get_usage() - $PERF->startmemory;
        $info['html'] .= '<span class="memoryused">RAM: '.display_size($info['memory_total']).'</span> ';
        $info['txt']  .= 'memory_total: '.$info['memory_total'].'B (' . display_size($info['memory_total']).') memory_growth: '.$info['memory_growth'].'B ('.display_size($info['memory_growth']).') ';
    }

    $inc = get_included_files();
    //error_log(print_r($inc,1));
    $info['includecount'] = count($inc);
    $info['html'] .= '<span class="included">Included '.$info['includecount'].' files</span> ';
    $info['txt']  .= 'includecount: '.$info['includecount'].' ';

    if (!empty($PERF->dbqueries)) {
        $info['dbqueries'] = $PERF->dbqueries;
        $info['html'] .= '<span class="dbqueries">DB queries '.$info['dbqueries'].'</span> ';
        $info['txt'] .= 'dbqueries: '.$info['dbqueries'].' ';
    }

    if (!empty($PERF->logwrites)) {
        $info['logwrites'] = $PERF->logwrites;
        $info['html'] .= '<span class="logwrites">Log writes '.$info['logwrites'].'</span> ';
        $info['txt'] .= 'logwrites: '.$info['logwrites'].' ';
    }

    if (function_exists('posix_times')) {
        $ptimes = posix_times();
        if (is_array($ptimes)) {
            foreach ($ptimes as $key => $val) {
                $info[$key] = $ptimes[$key] -  $PERF->startposixtimes[$key];
            }
            $info['html'] .= "<span class=\"posixtimes\">ticks: $info[ticks] user: $info[utime] sys: $info[stime] cuser: $info[cutime] csys: $info[cstime]</span> ";
            $info['txt'] .= "ticks: $info[ticks] user: $info[utime] sys: $info[stime] cuser: $info[cutime] csys: $info[cstime] ";
        }
    }

    // Grab the load average for the last minute
    // /proc will only work under some linux configurations
    // while uptime is there under MacOSX/Darwin and other unices
    if (is_readable('/proc/loadavg') && $loadavg = @file('/proc/loadavg')) {
        list($server_load) = explode(' ', $loadavg[0]);
        unset($loadavg);
    } else if ( function_exists('is_executable') && is_executable('/usr/bin/uptime') && $loadavg = `/usr/bin/uptime` ) {
        if (preg_match('/load averages?: (\d+[\.,:]\d+)/', $loadavg, $matches)) {
            $server_load = $matches[1];
        } else {
            trigger_error('Could not parse uptime output!');
        }
    }
    if (!empty($server_load)) {
        $info['serverload'] = $server_load;
        $info['html'] .= '<span class="serverload">Load average: '.$info['serverload'].'</span> ';
        $info['txt'] .= "serverload: {$info['serverload']} ";
    }

    if (isset($rcache->hits) && isset($rcache->misses)) {
        $info['rcachehits'] = $rcache->hits;
        $info['rcachemisses'] = $rcache->misses;
        $info['html'] .= '<span class="rcache">Record cache hit/miss ratio : '.
            "{$rcache->hits}/{$rcache->misses}</span> ";
        $info['txt'] .= 'rcache: '.
            "{$rcache->hits}/{$rcache->misses} ";
    }
    $info['html'] = '<div class="performanceinfo">'.$info['html'].'</div>';
    return $info;
}

function apd_get_profiling() {
    return shell_exec('pprofp -u ' . ini_get('apd.dumpdir') . '/pprof.' . getmypid() . '.*');
}

function remove_dir($dir, $content_only=false) {
    // if content_only=true then delete all but
    // the directory itself

    $handle = opendir($dir);
    while (false!==($item = readdir($handle))) {
        if($item != '.' && $item != '..') {
            if(is_dir($dir.'/'.$item)) {
                remove_dir($dir.'/'.$item);
            }else{
                unlink($dir.'/'.$item);
            }
        }
    }
    closedir($handle);
    if ($content_only) {
        return true;
    }
    return rmdir($dir);
}

/**
 * Function to check if a directory exists and optionally create it.
 *
 * @param string absolute directory path (must be under $CFG->dataroot)
 * @param boolean create directory if does not exist
 * @param boolean create directory recursively
 *
 * @return boolean true if directory exists or created
 */
function check_dir_exists($dir, $create=false, $recursive=false) {

    global $CFG;

    if (strstr($dir, $CFG->dataroot) === false) {
        debugging('Warning. Wrong call to check_dir_exists(). $dir must be an absolute path under $CFG->dataroot ("' . $dir . '" is incorrect)', DEBUG_DEVELOPER);
    }

    $status = true;

    if(!is_dir($dir)) {
        if (!$create) {
            $status = false;
        } else {
            umask(0000);
            if ($recursive) {
            /// PHP 5.0 has recursive mkdir parameter, but 4.x does not :-(
                $dir = str_replace('\\', '/', $dir); //windows compatibility
            /// We are going to make it recursive under $CFG->dataroot only
            /// (will help sites running open_basedir security and others)
                $dir = str_replace($CFG->dataroot . '/', '', $dir);
                $dirs = explode('/', $dir); /// Extract path parts
            /// Iterate over each part with start point $CFG->dataroot
                $dir = $CFG->dataroot . '/';
                foreach ($dirs as $part) {
                    if ($part == '') {
                        continue;
                    }
                    $dir .= $part.'/';
                    if (!is_dir($dir)) {
                        if (!mkdir($dir, $CFG->directorypermissions)) {
                            $status = false;
                            break;
                        }
                    }
                }
            } else {
                $status = mkdir($dir, $CFG->directorypermissions);
            }
        }
    }
    return $status;
}

function report_session_error() {
    global $CFG, $FULLME;

    if (empty($CFG->lang)) {
        $CFG->lang = "en";
    }
    // Set up default theme and locale
    theme_setup();
    moodle_setlocale();

    //clear session cookies
    setcookie('MoodleSession'.$CFG->sessioncookie, '', time() - 3600, $CFG->sessioncookiepath);
    setcookie('MoodleSessionTest'.$CFG->sessioncookie, '', time() - 3600, $CFG->sessioncookiepath);
    //increment database error counters
    if (isset($CFG->session_error_counter)) {
        set_config('session_error_counter', 1 + $CFG->session_error_counter);
    } else {
        set_config('session_error_counter', 1);
    }
    redirect($FULLME, get_string('sessionerroruser2', 'error'), 5);
}


/**
 * Detect if an object or a class contains a given property
 * will take an actual object or the name of a class
 * @param mix $obj Name of class or real object to test
 * @param string $property name of property to find
 * @return bool true if property exists
 */
function object_property_exists( $obj, $property ) {
    if (is_string( $obj )) {
        $properties = get_class_vars( $obj );
    }
    else {
        $properties = get_object_vars( $obj );
    }
    return array_key_exists( $property, $properties );
}


/**
 * Detect a custom script replacement in the data directory that will
 * replace an existing moodle script
 * @param string $urlpath path to the original script
 * @return string full path name if a custom script exists
 * @return bool false if no custom script exists
 */
function custom_script_path($urlpath='') {
    global $CFG;

    // set default $urlpath, if necessary
    if (empty($urlpath)) {
        $urlpath = qualified_me(); // e.g. http://www.this-server.com/moodle/this-script.php
    }

    // $urlpath is invalid if it is empty or does not start with the Moodle wwwroot
    if (empty($urlpath) or (strpos($urlpath, $CFG->wwwroot) === false )) {
        return false;
    }

    // replace wwwroot with the path to the customscripts folder and clean path
    $scriptpath = $CFG->customscripts . clean_param(substr($urlpath, strlen($CFG->wwwroot)), PARAM_PATH);

    // remove the query string, if any
    if (($strpos = strpos($scriptpath, '?')) !== false) {
        $scriptpath = substr($scriptpath, 0, $strpos);
    }

    // remove trailing slashes, if any
    $scriptpath = rtrim($scriptpath, '/\\');

    // append index.php, if necessary
    if (is_dir($scriptpath)) {
        $scriptpath .= '/index.php';
    }

    // check the custom script exists
    if (file_exists($scriptpath)) {
        return $scriptpath;
    } else {
        return false;
    }
}

/**
 * Wrapper function to load necessary editor scripts
 * to $CFG->editorsrc array. Params can be coursei id
 * or associative array('courseid' => value, 'name' => 'editorname').
 * @uses $CFG
 * @param mixed $args Courseid or associative array.
 */
function loadeditor($args) {
    global $CFG;
    include($CFG->libdir .'/editorlib.php');
    return editorObject::loadeditor($args);
}

/**
 * Returns whether or not the user object is a remote MNET user. This function
 * is in moodlelib because it does not rely on loading any of the MNET code.
 *
 * @param object $user A valid user object
 * @return bool        True if the user is from a remote Moodle.
 */
function is_mnet_remote_user($user) {
    global $CFG;

    if (!isset($CFG->mnet_localhost_id)) {
        include_once $CFG->dirroot . '/mnet/lib.php';
        $env = new mnet_environment();
        $env->init();
        unset($env);
    }

    return (!empty($user->mnethostid) && $user->mnethostid != $CFG->mnet_localhost_id);
}

/**
 * Checks if a given plugin is in the list of enabled enrolment plugins.
 *
 * @param string $auth Enrolment plugin.
 * @return boolean Whether the plugin is enabled.
 */
function is_enabled_enrol($enrol='') {
    global $CFG;

    // use the global default if not specified
    if ($enrol == '') {
        $enrol = $CFG->enrol;
    }
    return in_array($enrol, explode(',', $CFG->enrol_plugins_enabled));
}

/**
 * This function will search for browser prefereed languages, setting Moodle
 * to use the best one available if $SESSION->lang is undefined
 */
function setup_lang_from_browser() {

    global $CFG, $SESSION, $USER;

    if (!empty($SESSION->lang) or !empty($USER->lang)) {
        // Lang is defined in session or user profile, nothing to do
        return;
    }

    if (!isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) { // There isn't list of browser langs, nothing to do
        return;
    }

/// Extract and clean langs from headers
    $rawlangs = $_SERVER['HTTP_ACCEPT_LANGUAGE'];
    $rawlangs = str_replace('-', '_', $rawlangs);         // we are using underscores
    $rawlangs = explode(',', $rawlangs);                  // Convert to array
    $langs = array();

    $order = 1.0;
    foreach ($rawlangs as $lang) {
        if (strpos($lang, ';') === false) {
            $langs[(string)$order] = $lang;
            $order = $order-0.01;
        } else {
            $parts = explode(';', $lang);
            $pos = strpos($parts[1], '=');
            $langs[substr($parts[1], $pos+1)] = $parts[0];
        }
    }
    krsort($langs, SORT_NUMERIC);

    $langlist = get_list_of_languages();

/// Look for such langs under standard locations
    foreach ($langs as $lang) {
        $lang = strtolower(clean_param($lang.'_utf8', PARAM_SAFEDIR)); // clean it properly for include
        if (!array_key_exists($lang, $langlist)) {
            continue; // language not allowed, try next one
        }
        if (file_exists($CFG->dataroot .'/lang/'. $lang) or file_exists($CFG->dirroot .'/lang/'. $lang)) {
            $SESSION->lang = $lang; /// Lang exists, set it in session
            break; /// We have finished. Go out
        }
    }
    return;
}

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?>