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<?php

// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.

/**
* This file contains the parent class for moodle blocks, block_base.
*
* @package core
* @subpackage block
* @license http://www.gnu.org/copyleft/gpl.html GNU Public License
*/

/// Constants

/**
* Block type of list. Contents of block should be set as an associative array in the content object as items ($this->content->items). Optionally include footer text in $this->content->footer.
*/
define('BLOCK_TYPE_LIST', 1);

/**
* Block type of text. Contents of block should be set to standard html text in the content object as items ($this->content->text). Optionally include footer text in $this->content->footer.
*/
define('BLOCK_TYPE_TEXT', 2);
/**
* Block type of tree. $this->content->items is a list of tree_item objects and $this->content->footer is a string.
*/
define('BLOCK_TYPE_TREE', 3);

/**
* Class for describing a moodle block, all Moodle blocks derive from this class
*
* @author Jon Papaioannou
* @package blocks
*/
class block_base {

    /**
* Internal var for storing/caching translated strings
* @var string $str
*/
    var $str;

    /**
* The title of the block to be displayed in the block title area.
* @var string $title
*/
    var $title = NULL;

    /**
* The name of the block to be displayed in the block title area if the title is empty.
* @var string arialabel
*/
    var $arialabel = NULL;

    /**
* The type of content that this block creates. Currently support options - BLOCK_TYPE_LIST, BLOCK_TYPE_TEXT
* @var int $content_type
*/
    var $content_type = BLOCK_TYPE_TEXT;

    /**
* An object to contain the information to be displayed in the block.
* @var stdObject $content
*/
    var $content = NULL;

    /**
* A string generated by {@link _add_edit_controls()} to display block manipulation links when the user is in editing mode.
* @var string $edit_controls
*/
    var $edit_controls = NULL;

    /**
* The initialized instance of this block object.
* @var block $instance
*/
    var $instance = NULL;

    /**
* The page that this block is appearing on.
* @var moodle_page
*/
    public $page = NULL;

    /**
* This blocks's context.
* @var stdClass
*/
    public $context = NULL;

    /**
* An object containing the instance configuration information for the current instance of this block.
* @var stdObject $config
*/
    var $config = NULL;

    /**
* How often the cronjob should run, 0 if not at all.
* @var int $cron
*/

    var $cron = NULL;

/// Class Functions

    /**
* Fake constructor to keep PHP5 happy
*
*/
    function __construct() {
        $this->init();
    }

    /**
* Function that can be overridden to do extra cleanup before
* the database tables are deleted. (Called once per block, not per instance!)
*/
    function before_delete() {
    }

    /**
* Returns the block name, as present in the class name,
* the database, the block directory, etc etc.
*
* @return string
*/
    function name() {
        // Returns the block name, as present in the class name,
        // the database, the block directory, etc etc.
        static $myname;
        if ($myname === NULL) {
            $myname = strtolower(get_class($this));
            $myname = substr($myname, strpos($myname, '_') + 1);
        }
        return $myname;
    }

    /**
* Parent class version of this function simply returns NULL
* This should be implemented by the derived class to return
* the content object.
*
* @return stdObject
*/
    function get_content() {
        // This should be implemented by the derived class.
        return NULL;
    }

    /**
* Returns the class $title var value.
*
* Intentionally doesn't check if a title is set.
* This is already done in {@link _self_test()}
*
* @return string $this->title
*/
    function get_title() {
        // Intentionally doesn't check if a title is set. This is already done in _self_test()
        return $this->title;
    }

    /**
* Returns the class $content_type var value.
*
* Intentionally doesn't check if content_type is set.
* This is already done in {@link _self_test()}
*
* @return string $this->content_type
*/
    function get_content_type() {
        // Intentionally doesn't check if a content_type is set. This is already done in _self_test()
        return $this->content_type;
    }

    /**
* Returns true or false, depending on whether this block has any content to display
* and whether the user has permission to view the block
*
* @return boolean
*/
    function is_empty() {
        if ( !has_capability('moodle/block:view', $this->context) ) {
            return true;
        }

        $this->get_content();
        return(empty($this->content->text) && empty($this->content->footer));
    }

    /**
* First sets the current value of $this->content to NULL
* then calls the block's {@link get_content()} function
* to set its value back.
*
* @return stdObject
*/
    function refresh_content() {
        // Nothing special here, depends on content()
        $this->content = NULL;
        return $this->get_content();
    }

    /**
* Return a block_contents object representing the full contents of this block.
*
* This internally calls ->get_content(), and then adds the editing controls etc.
*
* You probably should not override this method, but instead override
* {@link html_attributes()}, {@link formatted_contents()} or {@link get_content()},
* {@link hide_header()}, {@link (get_edit_controls)}, etc.
*
* @return block_contents a representation of the block, for rendering.
* @since Moodle 2.0.
*/
    public function get_content_for_output($output) {
        global $CFG;

        $bc = new block_contents($this->html_attributes());

        $bc->blockinstanceid = $this->instance->id;
        $bc->blockpositionid = $this->instance->blockpositionid;

        if ($this->instance->visible) {
            $bc->content = $this->formatted_contents($output);
            if (!empty($this->content->footer)) {
                $bc->footer = $this->content->footer;
            }
        } else {
            $bc->add_class('invisible');
        }

        if (!$this->hide_header()) {
            $bc->title = $this->title;
        }

        if (empty($bc->title)) {
            $bc->arialabel = new lang_string('pluginname', get_class($this));
            $this->arialabel = $bc->arialabel;
        }

        if ($this->page->user_is_editing()) {
            $bc->controls = $this->page->blocks->edit_controls($this);
        } else {
            // we must not use is_empty on hidden blocks
            if ($this->is_empty() && !$bc->controls) {
                return null;
            }
        }

        if (empty($CFG->allowuserblockhiding)
                || (empty($bc->content) && empty($bc->footer))
                || !$this->instance_can_be_collapsed()) {
            $bc->collapsible = block_contents::NOT_HIDEABLE;
        } else if (get_user_preferences('block' . $bc->blockinstanceid . 'hidden', false)) {
            $bc->collapsible = block_contents::HIDDEN;
        } else {
            $bc->collapsible = block_contents::VISIBLE;
        }

        $bc->annotation = ''; // TODO MDL-19398 need to work out what to say here.

        return $bc;
    }

    /**
* Convert the contents of the block to HTML.
*
* This is used by block base classes like block_list to convert the structured
* $this->content->list and $this->content->icons arrays to HTML. So, in most
* blocks, you probaby want to override the {@link get_contents()} method,
* which generates that structured representation of the contents.
*
* @param $output The core_renderer to use when generating the output.
* @return string the HTML that should appearn in the body of the block.
* @since Moodle 2.0.
*/
    protected function formatted_contents($output) {
        $this->get_content();
        $this->get_required_javascript();
        if (!empty($this->content->text)) {
            return $this->content->text;
        } else {
            return '';
        }
    }

    /**
* Tests if this block has been implemented correctly.
* Also, $errors isn't used right now
*
* @return boolean
*/

    function _self_test() {
        // Tests if this block has been implemented correctly.
        // Also, $errors isn't used right now
        $errors = array();

        $correct = true;
        if ($this->get_title() === NULL) {
            $errors[] = 'title_not_set';
            $correct = false;
        }
        if (!in_array($this->get_content_type(), array(BLOCK_TYPE_LIST, BLOCK_TYPE_TEXT, BLOCK_TYPE_TREE))) {
            $errors[] = 'invalid_content_type';
            $correct = false;
        }
        //following selftest was not working when roles&capabilities were used from block
/* if ($this->get_content() === NULL) {
$errors[] = 'content_not_set';
$correct = false;
}*/
        $formats = $this->applicable_formats();
        if (empty($formats) || array_sum($formats) === 0) {
            $errors[] = 'no_formats';
            $correct = false;
        }

        $width = $this->preferred_width();
        if (!is_int($width) || $width <= 0) {
            $errors[] = 'invalid_width';
            $correct = false;
        }
        return $correct;
    }

    /**
* Subclasses should override this and return true if the
* subclass block has a config_global.html file.
*
* @return boolean
*/
    function has_config() {
        return false;
    }

    /**
* Default behavior: save all variables as $CFG properties
* You don't need to override this if you 're satisfied with the above
*
* @param array $data
* @return boolean
*/
    function config_save($data) {
        foreach ($data as $name => $value) {
            set_config($name, $value);
        }
        return true;
    }

    /**
* Which page types this block may appear on.
*
* The information returned here is processed by the
* {@link blocks_name_allowed_in_format()} function. Look there if you need
* to know exactly how this works.
*
* Default case: everything except mod and tag.
*
* @return array page-type prefix => true/false.
*/
    function applicable_formats() {
        // Default case: the block can be used in courses and site index, but not in activities
        return array('all' => true, 'mod' => false, 'tag' => false);
    }


    /**
* Default return is false - header will be shown
* @return boolean
*/
    function hide_header() {
        return false;
    }

    /**
* Return any HTML attributes that you want added to the outer <div> that
* of the block when it is output.
*
* Because of the way certain JS events are wired it is a good idea to ensure
* that the default values here still get set.
* I found the easiest way to do this and still set anything you want is to
* override it within your block in the following way
*
* <code php>
* function html_attributes() {
* $attributes = parent::html_attributes();
* $attributes['class'] .= ' mynewclass';
* return $attributes;
* }
* </code>
*
* @return array attribute name => value.
*/
    function html_attributes() {
        $attributes = array(
            'id' => 'inst' . $this->instance->id,
            'class' => 'block_' . $this->name(). ' block',
            'role' => $this->get_aria_role()
        );
        if ($this->instance_can_be_docked() && get_user_preferences('docked_block_instance_'.$this->instance->id, 0)) {
            $attributes['class'] .= ' dock_on_load';
        }
        return $attributes;
    }

    /**
* Set up a particular instance of this class given data from the block_insances
* table and the current page. (See {@link block_manager::load_blocks()}.)
*
* @param stdClass $instance data from block_insances, block_positions, etc.
* @param moodle_page $the page this block is on.
*/
    function _load_instance($instance, $page) {
        if (!empty($instance->configdata)) {
            $this->config = unserialize(base64_decode($instance->configdata));
        }
        $this->instance = $instance;
        $this->context = context_block::instance($instance->id);
        $this->page = $page;
        $this->specialization();
    }

    function get_required_javascript() {
        if ($this->instance_can_be_docked() && !$this->hide_header()) {
            $this->page->requires->js_init_call('M.core_dock.init_genericblock', array($this->instance->id));
            user_preference_allow_ajax_update('docked_block_instance_'.$this->instance->id, PARAM_INT);
        }
    }

    /**
* This function is called on your subclass right after an instance is loaded
* Use this function to act on instance data just after it's loaded and before anything else is done
* For instance: if your block will have different title's depending on location (site, course, blog, etc)
*/
    function specialization() {
        // Just to make sure that this method exists.
    }

    /**
* Is each block of this type going to have instance-specific configuration?
* Normally, this setting is controlled by {@link instance_allow_multiple()}: if multiple
* instances are allowed, then each will surely need its own configuration. However, in some
* cases it may be necessary to provide instance configuration to blocks that do not want to
* allow multiple instances. In that case, make this function return true.
* I stress again that this makes a difference ONLY if {@link instance_allow_multiple()} returns false.
* @return boolean
*/
    function instance_allow_config() {
        return false;
    }

    /**
* Are you going to allow multiple instances of each block?
* If yes, then it is assumed that the block WILL USE per-instance configuration
* @return boolean
*/
    function instance_allow_multiple() {
        // Are you going to allow multiple instances of each block?
        // If yes, then it is assumed that the block WILL USE per-instance configuration
        return false;
    }

    /**
* Default behavior: print the config_instance.html file
* You don't need to override this if you're satisfied with the above
*
* @deprecated since Moodle 2.0.
* @return boolean whether anything was done. Blocks should use edit_form.php.
*/
    function instance_config_print() {
        global $CFG, $DB, $OUTPUT;
        // Default behavior: print the config_instance.html file
        // You don't need to override this if you're satisfied with the above
        if (!$this->instance_allow_multiple() && !$this->instance_allow_config()) {
            return false;
        }

        if (is_file($CFG->dirroot .'/blocks/'. $this->name() .'/config_instance.html')) {
            echo $OUTPUT->box_start('generalbox boxaligncenter blockconfiginstance');
            include($CFG->dirroot .'/blocks/'. $this->name() .'/config_instance.html');
            echo $OUTPUT->box_end();
        } else {
            notice(get_string('blockconfigbad'), str_replace('blockaction=', 'dummy=', qualified_me()));
        }

        return true;
    }

    /**
* Serialize and store config data
*/
    function instance_config_save($data, $nolongerused = false) {
        global $DB;
        $DB->set_field('block_instances', 'configdata', base64_encode(serialize($data)),
                array('id' => $this->instance->id));
    }

    /**
* Replace the instance's configuration data with those currently in $this->config;
*/
    function instance_config_commit($nolongerused = false) {
        global $DB;
        $this->instance_config_save($this->config);
    }

    /**
* Do any additional initialization you may need at the time a new block instance is created
* @return boolean
*/
    function instance_create() {
        return true;
    }

    /**
* Delete everything related to this instance if you have been using persistent storage other than the configdata field.
* @return boolean
*/
    function instance_delete() {
        return true;
    }

    /**
* Allows the block class to have a say in the user's ability to edit (i.e., configure) blocks of this type.
* The framework has first say in whether this will be allowed (e.g., no editing allowed unless in edit mode)
* but if the framework does allow it, the block can still decide to refuse.
* @return boolean
*/
    function user_can_edit() {
        global $USER;

        if (has_capability('moodle/block:edit', $this->context)) {
            return true;
        }

        // The blocks in My Moodle are a special case. We want them to inherit from the user context.
        if (!empty($USER->id)
            && $this->instance->parentcontextid == $this->page->context->id // Block belongs to this page
            && $this->page->context->contextlevel == CONTEXT_USER // Page belongs to a user
            && $this->page->context->instanceid == $USER->id) { // Page belongs to this user
            return has_capability('moodle/my:manageblocks', $this->page->context);
        }

        return false;
    }

    /**
* Allows the block class to have a say in the user's ability to create new instances of this block.
* The framework has first say in whether this will be allowed (e.g., no adding allowed unless in edit mode)
* but if the framework does allow it, the block can still decide to refuse.
* This function has access to the complete page object, the creation related to which is being determined.
*
* @param moodle_page $page
* @return boolean
*/
    function user_can_addto($page) {
        global $USER;

        // The blocks in My Moodle are a special case and use a different capability.
        if (!empty($USER->id)
            && $page->context->contextlevel == CONTEXT_USER // Page belongs to a user
            && $page->context->instanceid == $USER->id // Page belongs to this user
            && $page->pagetype == 'my-index') { // Ensure we are on the My Moodle page
            $capability = 'block/' . $this->name() . ':myaddinstance';
            return $this->has_add_block_capability($page, $capability)
                    && has_capability('moodle/my:manageblocks', $page->context);
        }

        $capability = 'block/' . $this->name() . ':addinstance';
        if ($this->has_add_block_capability($page, $capability)
                && has_capability('moodle/block:edit', $page->context)) {
            return true;
        }

        return false;
    }

    /**
* Returns true if the user can add a block to a page.
*
* @param moodle_page $page
* @param string $capability the capability to check
* @return boolean true if user can add a block, false otherwise.
*/
    private function has_add_block_capability($page, $capability) {
        // Check if the capability exists.
        if (!get_capability_info($capability)) {
            // Debug warning that the capability does not exist, but no more than once per page.
            static $warned = array();
            if (!isset($warned[$this->name()])) {
                debugging('The block ' .$this->name() . ' does not define the standard capability ' .
                        $capability , DEBUG_DEVELOPER);
                $warned[$this->name()] = 1;
            }
            // If the capability does not exist, the block can always be added.
            return true;
        } else {
            return has_capability($capability, $page->context);
        }
    }

    static function get_extra_capabilities() {
        return array('moodle/block:view', 'moodle/block:edit');
    }

    // Methods deprecated in Moodle 2.0 ========================================

    /**
* Default case: the block wants to be 180 pixels wide
* @deprecated since Moodle 2.0.
* @return int
*/
    function preferred_width() {
        return 180;
    }

    /** @deprecated since Moodle 2.0. */
    function _print_block() {
        throw new coding_exception('_print_block is no longer used. It was a private ' .
                'method of the block class, only for use by the blocks system. You ' .
                'should not have been calling it anyway.');
    }

    /** @deprecated since Moodle 2.0. */
    function _print_shadow() {
        throw new coding_exception('_print_shadow is no longer used. It was a private ' .
                'method of the block class, only for use by the blocks system. You ' .
                'should not have been calling it anyway.');
    }

    /** @deprecated since Moodle 2.0. */
    function _title_html() {
        throw new coding_exception('_title_html is no longer used. It was a private ' .
                'method of the block class, only for use by the blocks system. You ' .
                'should not have been calling it anyway.');
    }

    /** @deprecated since Moodle 2.0. */
    function _add_edit_controls() {
        throw new coding_exception('_add_edit_controls is no longer used. It was a private ' .
                'method of the block class, only for use by the blocks system. You ' .
                'should not have been calling it anyway.');
    }

    /** @deprecated since Moodle 2.0. */
    function config_print() {
        throw new coding_exception('config_print() can no longer be used. Blocks should use a settings.php file.');
    }

    /**
* Can be overridden by the block to prevent the block from being dockable.
*
* @return bool
*/
    public function instance_can_be_docked() {
        global $CFG;
        return (!empty($CFG->allowblockstodock) && $this->page->theme->enable_dock);
    }

    /**
* If overridden and set to false by the block it will not be hidable when
* editing is turned on.
*
* @return bool
*/
    public function instance_can_be_hidden() {
        return true;
    }

    /**
* If overridden and set to false by the block it will not be collapsible.
*
* @return bool
*/
    public function instance_can_be_collapsed() {
        return true;
    }

    /** @callback callback functions for comments api */
    public static function comment_template($options) {
        $ret = <<<EOD
<div class="comment-userpicture">___picture___</div>
<div class="comment-content">
    ___name___ - <span>___time___</span>
    <div>___content___</div>
</div>
EOD;
        return $ret;
    }
    public static function comment_permissions($options) {
        return array('view'=>true, 'post'=>true);
    }
    public static function comment_url($options) {
        return null;
    }
    public static function comment_display($comments, $options) {
        return $comments;
    }
    public static function comment_add(&$comments, $options) {
        return true;
    }

    /**
* Returns the aria role attribute that best describes this block.
*
* Region is the default, but this should be overridden by a block is there is a region child, or even better
* a landmark child.
*
* Options are as follows:
* - landmark
* - application
* - banner
* - complementary
* - contentinfo
* - form
* - main
* - navigation
* - search
*
* @return string
*/
    public function get_aria_role() {
        return 'complementary';
    }
}

/**
* Specialized class for displaying a block with a list of icons/text labels
*
* The get_content method should set $this->content->items and (optionally)
* $this->content->icons, instead of $this->content->text.
*
* @author Jon Papaioannou
* @package blocks
*/

class block_list extends block_base {
    var $content_type = BLOCK_TYPE_LIST;

    function is_empty() {
        if ( !has_capability('moodle/block:view', $this->context) ) {
            return true;
        }

        $this->get_content();
        return (empty($this->content->items) && empty($this->content->footer));
    }

    protected function formatted_contents($output) {
        $this->get_content();
        $this->get_required_javascript();
        if (!empty($this->content->items)) {
            return $output->list_block_contents($this->content->icons, $this->content->items);
        } else {
            return '';
        }
    }

    function html_attributes() {
        $attributes = parent::html_attributes();
        $attributes['class'] .= ' list_block';
        return $attributes;
    }

}

/**
* Specialized class for displaying a tree menu.
*
* The {@link get_content()} method involves setting the content of
* <code>$this->content->items</code> with an array of {@link tree_item}
* objects (these are the top-level nodes). The {@link tree_item::children}
* property may contain more tree_item objects, and so on. The tree_item class
* itself is abstract and not intended for use, use one of it's subclasses.
*
* Unlike {@link block_list}, the icons are specified as part of the items,
* not in a separate array.
*
* @author Alan Trick
* @package blocks
* @internal this extends block_list so we get is_empty() for free
*/
class block_tree extends block_list {

    /**
* @var int specifies the manner in which contents should be added to this
* block type. In this case <code>$this->content->items</code> is used with
* {@link tree_item}s.
*/
    public $content_type = BLOCK_TYPE_TREE;

    /**
* Make the formatted HTML ouput.
*
* Also adds the required javascript call to the page output.
*
* @param core_renderer $output
* @return string HTML
*/
    protected function formatted_contents($output) {
        // based of code in admin_tree
        global $PAGE; // TODO change this when there is a proper way for blocks to get stuff into head.
        static $eventattached;
        if ($eventattached===null) {
            $eventattached = true;
        }
        if (!$this->content) {
            $this->content = new stdClass;
            $this->content->items = array();
        }
        $this->get_required_javascript();
        $this->get_content();
        $content = $output->tree_block_contents($this->content->items,array('class'=>'block_tree list'));
        if (isset($this->id) && !is_numeric($this->id)) {
            $content = $output->box($content, 'block_tree_box', $this->id);
        }
        return $content;
    }
}
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