wplicense.php

<?php
/*
Plugin Name: Creative Commons
Description: Official Creative Commons plugin for WordPress. Allows users to select and display Creative Commons licenses for their content. Partially inspired by the License plugin by mitcho (Michael Yoshitaka Erlewine) and Brett Mellor, as well as the original WpLicense plugin by CC CTO Nathan R. Yergler.
Version: 2.0
Author: Bjorn Wijers <burobjorn@burobjorn.nl>, Tarmo Toikkanen <tarmo@iki.fi>, Matt Lee <mattl@creativecommons.org>
Plugin URI: http://wiki.creativecommons.org/WpLicense
License: GPLv2 or later versions
*/

if( ! class_exists('WPLicense') ) { 
  class WPLicense {

    // MAKE SURE THE PLUGIN HEADER HAS THE SAME VERSION NUMBER!
    const VERSION = '2.0-beta'; 

    private $plugin_url; 
    private $localization_domain = 'WPLicense';
    private $locale; 

    function __construct() {
      $this->plugin_url =  WP_PLUGIN_URL .'/' . str_replace( basename( __FILE__ ), "", plugin_basename( __FILE__ ) );

      // language setup
      $this->locale = get_locale();
      $mo     = dirname(__FILE__) . '/languages/' . $this->locale . '.mo';
      load_textdomain($this->localization_domain, $mo);
      
      // add admin.js to wp-admin pages and displays the site license settings 
      // in the Settings->General settings page unless you're running WordPress 
      // Multisite (Network) and the superadmin has disabled this.  
      add_action( 'admin_init', array(&$this, 'license_admin_init') );
  


      // Selecting a license for individual posts or pages is only possible if the settings of the site allow it
      // by default it does allow it.
      if( $this->allow_content_override_site_license() ) {
        add_action( 'post_submitbox_misc_actions', array(&$this, 'post_page_license_settings_html') );
        add_action( 'page_submitbox_misc_actions', array(&$this, 'post_page_license_settings_html') );
        add_action( 'save_post',                   array(&$this, 'save_license') );
      }

      // Selecting a license as a user for all your content is only possible if the settings of the site allow it, 
      // by default it will allow it.
      if( $this->allow_user_override_site_license() ) {
        add_action( 'personal_options',            array(&$this, 'user_license_settings_html') );
        add_action( 'personal_options_update',     array(&$this, 'save_license') );
      }
      
      // this implements the license plugin as a widget.
      // TODO: Widget needs more testing with the new approach 
      add_action( 'widgets_init', array(&$this, 'license_as_widget') );
    
      // if the plugin is installed in multisite environment allow to set the 
      // options for all sites as default from the network options
      if( is_multisite() ) {
        add_action('wpmu_options', array(&$this, 'network_license_settings_html') , 10, 0);
        add_action('update_wpmu_options', array(&$this, 'save_license'), 10, 0 );
      }
    }

    function register_site_settings() {
      register_setting( 'general', 'license', array(&$this, '_wrapper_settings_api_verify') );
      add_settings_section( 'license-section', 'License Settings', array(&$this, 'settings_license_section'), 'general', 'license-section');

      add_settings_field( 'license', '<label for="license">' . __('License your site', $this->localization_domain) . '</label>', array(&$this, 'setting_license_field'), 'general', 'license-section');
      
      add_settings_field( 'warning_txt', '<label for="warning_txt">' . __('Add license warning text', $this->localization_domain) . '</label>', array(&$this, 'setting_warning_field'), 'general', 'license-section');
      
      add_settings_field( 'attribution_to', '<label for="attribution_to">' . __('Set attribution to', $this->localization_domain) . '</label>', array(&$this, 'setting_attribution_field'), 'general', 'license-section');
      add_settings_field( 'allow_user_override', '<label for="allow_user_override">' . __('Allow users override site license', $this->localization_domain) . '</label>', array(&$this, 'setting_user_override_license_field'), 'general', 'license-section');
      add_settings_field( 'allow_content_override', '<label for="allow_content_override">' . __('Allow license per post or page', $this->localization_domain) . '</label>', array(&$this, 'setting_content_override_license_field'), 'general', 'license-section');
    
    }

    function settings_license_section() {
      $this->display_settings_warning( $echo = true );
    }


    function setting_license_field() {
      $this->select_license_html( $location = 'site', $echo = true );
    }
    
    function setting_warning_field() {
      $license = $this->get_license( $location = 'site');
      $w = esc_html( $license['warning_txt'] );
      echo "<input name='license[warning_txt]' type='text' maxlength='250' id='warning-txt' value='$w' />";
    }

    function setting_attribution_field() {
      $this->select_attribute_to_html( $location = 'site', $echo = true );
    }

    // only used once in site admin
    function setting_user_override_license_field() {
      $license = $this->get_license( $location = 'site');
      $checked = ( array_key_exists('user_override_license', $license) ) ? checked( $license['user_override_license'], 'true', false ) : '';
      echo "<input name='license[user_override_license]' type='checkbox' " . $checked . " id='user-override-license' value='true' />";
    }
    
    // only used once in site admin
    function setting_content_override_license_field() {
      $license = $this->get_license( $location = 'site');
      $checked = ( array_key_exists('content_override_license', $license) ) ? checked( $license['content_override_license'], 'true', false ) : '';
      echo "<input name='license[content_override_license]' type='checkbox' " . $checked . " id='content-override-license' value='true' />";
    }

    /** 
     * Check if a site may override the network license.
     *
     * If a network license override is allowed, a site admin may change their 
     * site's license. The rights are cascading: if a site admin may change a 
     * site's license, she may also allow a user to select their own license. 
     * if a site admin may not change the license she will also not be allowed 
     * to let a user pick their own license. A siteadmin may also enable to 
     * have a license per content.
     *
     * @return bool true if the network license override is allowed, false 
     * otherwise
     */
    function allow_site_override_network_license() {
      $license = $this->get_license( $location = 'network' );
      // gotcha: using true as string instead of bool since it will be a string value 
      // returned from the settings form
      if( 'true' == $license['site_override_license'] ) {
        return true;
      } else {
        return false;
      }  
    }
    
    function allow_user_override_site_license() {
      if( is_multisite() && ! $this->allow_site_override_network_license() ) {
        return false;
      } else {
        $license = $this->get_license ( $location = 'site' );
        if( array_key_exists('user_override_license', $license) && 'true' == $license['user_override_license'] ) {
          return true;
        } else {
          return false;
        }
      }
    }

    function allow_content_override_site_license() {
      if( is_multisite() && ! $this->allow_site_override_network_license() ) {
        return false;
      } else {
        $license = $this->get_license ( $location = 'site' );
        if( array_key_exists('content_override_license', $license) && 'true' == $license['content_override_license'] ) {
          return true;
        } else {
          return false;
        }
      }
    }



    /**
     * Set a default license.
     * 
     * Hierarchy of license selection
     * If the plugin is used in a Multisite Network WordPress setup there is an 
     * option added to the network options to set a default license for all 
     * sites in this particular network. Each site will inherit this default. 
     * A sit owner may change this license (at least if the Multisite Admin 
     * allows it). On a site level (or single WordPress install) an admin may 
     * allow this site default license to be changed. If the site allows a 
     * user may change the default license for her/his posts. The same goes for 
     * posts/pages: if the site admin allows it these can be changed per post 
     * or page.  
     * 
     * 
     **/
    function plugin_default_license() {
      $this->_logger('Got default settings');
      return $license = array(
        'deed'                     => 'http://creativecommons.org/licenses/by-sa/4.0/',
        'image'                    => 'http://i.creativecommons.org/l/by-sa/4.0/88x31.png',
        'attribute_to'             => '',
        'title'                    => get_bloginfo('name'),
        'name'                     => 'Creative Commons Attribution-Share Alike 4.0 License',
        'sitename'                 => get_bloginfo(''),
        'siteurl'                  => get_bloginfo('url'),
        'author'                   => get_bloginfo(),
        'site_override_license'    => true,
        'user_override_license'    => true,
        'content_override_license' => true,
        'version'                  => self::VERSION,
        'warning_txt'             => __('The license shown may be overriden by individual content such as a single post or image.', $this->localization_domain)
      );
    }


    
    
    // 1) Check if it's allowed to have a license per content => check the 
    // content for a license. No license found or not allowed? Continue 2
    // 2) Check if it's allowed to have a license per user => check the 
    // content author and grab his/her license preference. No license found 
    // or user are not allowed to choose their own license? Continue 3
    // 3) Check if the site is part of a network => No? continue step 4a
    // Yes? continue step 4b
    // 4a) the site is NOT part of a network => Get license from options or 
    // return plugin's default 
    // 4b) The site is part of a network => check if the site may choose it's 
    // own license => check the options for a license. Not allowed or no 
    // license found Continue step 5
    // 5) Check the multisite options for a license and return if not found 
    // return plugin default     
    function get_license( $location = null ) {
      switch ($location) {
        case 'network' :
          $this->_logger('called network');
          $license = ( $network_license = get_site_option( 'license' ) ) ? $network_license : $this->plugin_default_license();
          break;
        
        case 'site':
          $this->_logger('called site');
          if( is_multisite() ) {
            $this->_logger('multisite, check network settings');
            $license = ( $site_license = get_option( 'license') ) ? $site_license : $this->get_license( 'network' );
          } else {
            $this->_logger('single site, get site license or else default settings');
            $license = ( $site_license = get_option( 'license') ) ? $site_license : $this->plugin_default_license();
          }
          break;

        case 'profile':
          $this->_logger('called profile');
          $license = ( $user_license = get_user_option( 'license' ) ) ? $user_license : $this->get_license( 'site' );
          break;

        case 'post-page':
          $this->_logger('called post-page');
          $license = ( $post_page_license = $this->get_post_page_license() ) ? $post_page_license : $this->get_license( 'profile' );
          break;

        // TODO need to check default structure below since this can cause way 
        // too many calls for the right license   
        case 'frontend':
          $this->_logger('get license for the frontend');
          if( is_multisite() ) {
            $this->_logger('get license: multisite');
            $license = $this->get_license( 'network' );
            $this->_logger('got network license');
            if( $this->allow_site_override_network_license() ) { 
              $this->_logger('site may override network license');
              $license = $this->get_license( 'site' );
              $site_license = $license; // keep track of site license cause we need to check it twice...
              $this->_logger('got site license');
              if( array_key_exists( 'user_override_license', $site_license ) && 'true' == $site_license['user_override_license'] ) {
                $this->_logger('user may override license');
                $license = $this->get_license( 'profile' );
                $this->_logger('got user license');
              } 
              if( array_key_exists('content_override_license', $site_license) && 'true' == $site_license['content_override_license'] ) {
                $this->_logger('content may override license');
                $license = $this->get_license( 'post-page' ); 
                $this->_logger('got content license');
              }
            }
          } else {
            $license = $this->get_license( 'site' );
            if( array_key_exists( 'user_override_license', $license ) && 'true' == $license['user_override_license'] ) {
              $license = $this->get_license( 'profile' );
            } 
            if( array_key_exists('content_override_license', $license) && 'true' == $license['content_override_license'] ) {
              $license = $this->get_license( 'post-page' ); 
            }
          }
          break;
      } 
      return $license;
    }


    // will use a variable prefix with underscore to make *really* sure this 
    // postmeta value will NOT be displayed to other users. The option is the 
    // same structure as everywhere: a serialized array.
    // (http://codex.wordpress.org/Function_Reference/add_post_meta)
    function get_post_page_license() {
      global $post; // TODO check if this can be done without a global and if we're always getting what we want
      $license = get_post_meta( $post->ID, '_license', true ); 
      if( is_array($license) && sizeof($license) > 0 ) {
        return $license;
      } else { 
        return false; 
      } 
    }



    // used in: 
    // - network settings
    // - site settings 
    // - profile settings (personal & others) 
    // - post/page edit screen (my own & others)
    function select_license_html( $location = null, $echo = true ) {
      // get the previously selected license from this site's options or the plugin's default license
      //$license = get_option('license', $this->plugin_default_license() );
      $license  = $this->get_license( $location );
      // add lang option 
      $lang = ( isset($this->locale) && ! empty($this->locale) ) ? 'lang=' . esc_attr($this->locale) : '';

      $html = '';
      $html .= "<span id='license-display'></span>";
      $html .= '<br id="license"><a title="' . __('Choose a Creative Commons license', $this->localization_domain) . '" class="thickbox edit-license" href="http://creativecommons.org/choose/?';
        $html .= 'partner=WordPress+License+Plugin&';
        $html .= $lang;  
        $html .= '&exit_url=' . $this->plugin_url . 'licensereturn.php?url=[license_url]%26name=[license_name]%26button=[license_button]%26deed=[deed_url]&';
        $html .= '&KeepThis=true&TB_iframe=true&height=500&width=600">' . __('Change license', $this->localization_domain);
      $html .=  '</a>';

      $html .= '<input type="hidden" value="'.$license['deed'].'" id="hidden-license-deed" name="license[deed]"/>';
      $html .= '<input type="hidden" value="'.$license['image'].'" id="hidden-license-image" name="license[image]"/>';
      $html .= '<input type="hidden" value="'.$license['name'].'" id="hidden-license-name" name="license[name]"/>';
      if( $echo ) {
        echo $html; 
      } else {
        return $html;
      }
    }


    // return default attribution options
    function get_attribution_options( $location ) {
      switch ( $location ) {
      
      case 'network':
          $attribution_options = array(
            'network_name' => sprintf( __('The network name: %s', $this->localization_domain), get_site_option('site_name') ), 
            'site_name'    => __("A site's name", $this->localization_domain),
            'display_name' => __('The author display name', $this->localization_domain),
            'other'        => __('Something completely differrent', $this->localization_domain)
          );
        break;
        
        case 'site':
          $attribution_options = array(
            'site_name'    => sprintf( __('The site name: %s', $this->localization_domain), get_bloginfo('site') ),
            'display_name' => __('The author display name', $this->localization_domain),
            'other'        => __('Something completely differrent', $this->localization_domain)
          );
        break;

        default: 
          if( $this->allow_user_override_site_license() ) {
            $attribution_options = array(
              'display_name' => __('The author display name', $this->localization_domain),
              'other'        => __('Something completely differrent', $this->localization_domain)
            );
          }            
        break;
      }
      
      return $attribution_options;     
    }




    function select_attribute_to_html( $location = null, $echo = true ) {
      $license = $this->get_license( $location ); 
      $attribute_options = $this->get_attribution_options( $location );


      $html = '';
      if( is_array($attribute_options) && sizeof($attribute_options) > 0 ) {
        foreach( $attribute_options as $attr_val => $attr_text) {
          $checked = '';
          $id = "license-$attr_val";
          $checked = checked($license['attribute_to'], $attr_val, false);
          $html .= "<label for='$id'><input type='radio' class='license-attribution-options' id='$id' $checked name='license[attribute_to]' value='$attr_val' />" . $attr_text . "</label><br/>\n";
        }
        if ( 'other' == $license['attribute_to'] ) {
          $class = ''; 
          $value = esc_html( $license['attribute_other'] );
          $url   = esc_url ( $license['attribute_other_url']);        
        } else {
          $class = 'hidden'; // hide the other input text field if the 'other' option is not ticked
          $value = '';
          $url = '';
        }

        $html .= "<p id='attribute-other-data' class='$class'>";
        $html .= "<label for='license-other-value'>". __('Attribution text:', $this->localization_domain) . "<br /><input type='text' value='$value' name='license[attribute_other]' id='license-other-value' class='large' size='45' /></label><br />"; //might need max length? TODO need to check hidden value if other prev was selected
        $html .= "<label for='license-other-value-url'>". __('Attribution url:', $this->localization_domain) . "<br /><input type='text' value='$url' name='license[attribute_other_url]' id='license-other-value-url' class='large' size='45' /></label>";
        $html .= '</p>';
      }
      if( $echo ) {
        echo $html; 
      } else {
        return $html;
      }
    }


    // add a warning text at the site/network settings
    function display_settings_warning( $echo = false ) {
      $html = '';
      $html .= '<p>'; 
      $html .= __('WARNING: Changing these license settings after content has been added may change the licenses authors on the site have selected, effectively relicensing possibly all content on the site!', $this->localization_domain);   
      $html .= '</p>';
      if( $echo ) {
        echo $html; 
      } else {
        return $html;
      }
    }



    /** 
     * Renders the license settings WordPress Network Settings page 
     *
     * Using the settings rendered by this function a superadmin may set a 
     * default license for the WordPress Network. This will be used for all 
     * sites. If the superadmin allows it, siteadmins may change their site's
     * license and choose a different license than the default Network license.
     *
     * Called by wpmu_options action 
     *
     **/
    function network_license_settings_html() {

      // get the previously selected license from the network options or the plugin's default license
      //$license = get_site_option('license', $this->plugin_default_license() );
      $location = 'network';
      $license = $this->get_license( $location ); 


      $html  = '';
      $html .= "<h3>" . __('License settings', $this->localization_domain) . "</h3>\n";
      $html .= $this->display_settings_warning();

      $html .= wp_nonce_field('license-update', $name = 'license_wpnonce', $referer = true, $echo = false);
      $html .= "<table class='form-table'>\n";
      $html .= "<tbody>\n";


      $html .= $this->_license_settings_html( $location ); 
      
      $html .= "<tr valign='top'>\n";
      $html .= "\t<th scope='row'><label for='override-license'>" .  __("Allow siteadmins to change their site's license", $this->localization_domain) . "</label></th>\n";
      $html .= "\t<td><input name='site_override_license' type='checkbox'" . checked( $license['site_override_license'], 'true', false ) . " id='site_override-license' value='true' />";
      $html .= "</td>\n";
      $html .= "</tr>\n";

      $html .= "</tbody>\n";
      $html .= "</table>\n";
      
      echo $html;
    }

    // save license from network settings, user profile and post/page interface
    function save_license( $post_id = false ) {
      if( isset($_POST['license_wpnonce']) && wp_verify_nonce( $_POST['license_wpnonce'], 'license-update') ) { 
        if ( defined('IS_PROFILE_PAGE') && IS_PROFILE_PAGE) {
          $this->_save_user_license();
        } elseif( is_multisite() && defined('WP_NETWORK_ADMIN') && WP_NETWORK_ADMIN ) {
          $this->_save_network_license();
        } else {
          // presume we're in a post or page wp-admin environment
          // might need to deal with autosave 
          
          $this->_save_post_page_license( $post_id );
        }
      } else { 
        return $post_id;
      }
    }


    // wrapper so I can use the _verify_license_data function. 
    // @TODO refactor in the future 
    public function _wrapper_settings_api_verify( $data ) {
      return $this->_verify_license_data( 'site', $data );
    }


    // check the data before saving it
    // use $from ala get_license to determine where the data is coming from 
    // and what should be mandatory return an array or WP_Error?
    private function _verify_license_data( $from, $data = null ) {
      
      $license = array();

      // if no data was provided assume the data is in $_POST['license']
      if( is_null($data) && isset( $_POST['license'] ) ) { 
        $data = $_POST['license']; 
      }
      
      $license['version']          = self::VERSION; // always save the current version
      $license['deed']             = esc_url(  $data['deed']  ); 
      $license['image']            = esc_url(  $data['image'] );
      $license['name']             = esc_attr( $data['name']  );
      $license['attribute_to']     = esc_attr( $data['attribute_to'] );
      $license['attribute_other']  = esc_html( $data['attribute_other' ] );
      $license['attribute_other_url']  = esc_html( $data['attribute_other_url' ] );

      switch( $from ) {
        case 'network': // @TODO need to check this!
          if( isset( $_POST['site_override_license'] ) ) {
            $license['site_override_license'] = esc_attr( $_POST['site_override_license'] );
          }
          break;
        case 'site': 
          $license['user_override_license']    = esc_attr( $data['user_override_license'] );
          $license['content_override_license'] = esc_attr( $data['content_override_license'] );  
          $license['warning_txt']              = esc_html( $data['warning_txt'] );
        break;
      }
      return $license;
    }



    // validates & verifies the data and then saves the license in the site_options
    private function _save_network_license( ) {
      $license = $this->_verify_license_data( $from = 'network' ); 
      return update_site_option('license', $license);
    }

    // TODO: need to decide if the user option is global for all 
    // sites/blogs in a network. Also need to make sure that we're using 
    // the current profile user_id which might not be the 
    // current_user (e.g. admin changing license for a user).
    // validates & verifies the data and then saves the license in the user_options
    private function _save_user_license( ) {
      $license = $this->_verify_license_data( $from = 'profile' );
      $user_id = get_current_user_id();
      return update_user_option( $user_id, 'license', $license, $global = false );
    }

    // save post/page metadata due to it being an array it should not be shown 
    // in the post or page custom fields interface
    // using _license to hide it from the custom fields 
    private function _save_post_page_license( $post_id ) {
      $license = $this->_verify_license_data( $from = 'post-page' );
      return update_post_meta( $post_id,  '_license', $license);
    }


    function license_admin_init() {
      /* Register our script. */
      wp_register_script('license', WP_PLUGIN_URL . '/wplicense/js/admin.js');
      wp_enqueue_script("thickbox");
      wp_enqueue_style("thickbox");
      wp_enqueue_script('license');
      // if a siteadmin may change her site's license, show the settings 
      // otherwise don't bother 
      if( is_multisite() ) {
        if( $this->allow_site_override_network_license() ) {
          $this->register_site_settings();
        }
      } else {
        $this->register_site_settings();
      }
    }

    
    // render the html settings for the user profile 
    // TODO: add global option: if allowed use this license across all my sites 
    // in this network.
    function user_license_settings_html(){
      $location = 'profile';
      $html     = wp_nonce_field('license-update', $name = 'license_wpnonce', $referer = true, $echo = false);
      $html     .= $this->_license_settings_html( $location); 
      echo $html;
    } 
    
    function post_page_license_settings_html(){
      $location = 'post-page';
      $html  = '<div id="license" class="misc-pub-section misc-pub-section-last ">';
      $html .= wp_nonce_field('license-update', $name = 'license_wpnonce', $referer = true, $echo = false);
      $html .= '<strong>' . __('Licensed:', $this->localization_domain) . '</strong>';
      
      $html .= '<p>';
      $html .= $this->select_license_html( $location, $echo = false );  
      $html .= '</p>';
      
      $html .= '<p>';
      $html .= $this->select_attribute_to_html( $location, $echo = false );
      $html .= '</p>';
      $html .= '</div>';
      
      echo $html;
    }



    // DRY wrapper function used for profile settings and network settings
    private function _license_settings_html( $location ){
      $html ='';
      $html .= "<tr valign='top'>\n";
      $html .= "\t<th scope='row'><label for='license'>" .  __('Select a default license', $this->localization_domain) . "</label></th>\n";
      $html .= "\t<td>";
      $html .= $this->select_license_html( $location, $echo = false );
      $html .= "</td>\n";
      $html .= "</tr>\n";

      $html .= "<tr valign='top'>\n";
      $html .= "\t<th scope='row'><label for='attribute_to'>" .  __("Set attribution to", $this->localization_domain) . "</label></th>\n";
      $html .= "\t<td>";
      $html .= $this->select_attribute_to_html( $location, $echo = false );
      $html .= "</td>\n";
      $html .= "</tr>\n";
      
      return $html;
    }




    // add filters to this function so themers can easily change the html 
    // output
    public function print_license_html( $location = 'frontend', $echo = true ) {
      // TODO if the license is shown on a multiple items page (except the author 
      // archive page?) display the site (or network default license) 
      // default license including a warning that individual items may be 
      // licensed differently.  
      // add a filter to include the license with the excerpt & content filter
      // allow an option to switch this off


      $license = $this->get_license( $location );
      $html = '';
      if( is_array($license) && sizeof($license) > 0 ) {
        $deed_url      = esc_url( $license['deed'] ); 
        $image_url     = esc_url( $license['image'] );
        $license_name  = esc_html( $license['name'] );
        $warning       = (array_key_exists( 'warning_txt', $license ) ) ?  esc_html( $license['warning_txt'] ) : ''; // needs check


        if( is_array($attribution = $this->_get_attribution( $license ) ) ) {
          $attribute_text = isset( $attribution['text'] ) ? $attribution['text'] : '';
          $attribute_url  = isset( $attribution['url'] ) ? $attribution['url'] : '';
        }
      

        // it's a single entity so use the post->title otherwise use the site's 
        // title and add a warning that multiple items might have different 
        // licenses.
        if( is_singular() ) {
          global $post;
          if( is_object( $post ) ) { 
            $title_work = esc_html( $post->post_title );
            $warning_text = '';
          }  
        } else {
          $title_work   = get_bloginfo( 'name' );   
	  $attribute_url = esc_html(site_url());
          $warning_text = "<p class='license-warning'>" . esc_html( $warning ) . "</p>";
        }

        $html .= "<div class='license-wrap'>";
        $html .= "<a rel='license' href='$deed_url'>";
        $html .= "<img alt='" . __('Creative Commons License', $this->localization_domain) . "' style='border-width:0' src='$image_url' />";
        $html .= "</a><br />";
        $html .= "<span xmlns:dct='http://purl.org/dc/terms/' property='dct:title'>$title_work</span> "; 
	if (is_singular()) {
	        $html .= __('by', $this->localization_domain);
		$html .= " <a xmlns:cc='http://creativecommons.org/ns#' href='$attribute_url' property='cc:attributionName' rel='cc:attributionURL'>$attribute_text</a> "; 
	}
	$html .= sprintf( __('is licensed under a <a rel="license" href="%s">%s</a>.', $this->localization_domain), $deed_url, $license_name );
	//$html .= '<br />'; 
        //$html .= __('Based on a work at <a xmlns:dct="http://purl.org/dc/terms/" href="http://source.url" rel="dct:source">http://source.url</a>.', $this->localization_domain);
        //$html .='<br />';
        //$html .= __('Permissions beyond the scope of this license may be available at <a xmlns:cc="http://creativecommons.org/ns#" href="http://morepermissions.url" rel="cc:morePermissions">http://morepermissions.url</a>.', $this->localization_domain);
        $html .= $warning_text;
        $html .= '</div>';
      }
      if( $echo ) {
        echo $html;
      } else {
        return $html;
      }

    }

    // log all errors if wp_debug is active
    private function _logger( $string ) {
      if( defined('WP_DEBUG') && (WP_DEBUG == true) ) {
        error_log( $string ); 
      } else {
        return;
      }
    }

    private function _get_attribution( $license ) {
      if( is_array($license) && sizeof( $license ) > 0 ){
        $attribution_option = isset( $license['attribute_to'] ) ? $license['attribute_to'] : null;  
      }

      $attribution = array();

      switch($attribution_option) { 
      
        case 'network_name': 
          $attribution['text'] = esc_html( get_site_option('site_name') );
          $attribution['url']  = esc_url( get_permalink() );
          break;

        case 'site_name': 
          $attribution['text'] = esc_html( get_bloginfo('site') );
          $attribution['url']  = esc_url( get_permalink() );
          break;

        case 'display_name': 
	  // If displaying multiple posts, the display_name (author) will be reverted to site name later.
	  $attribution['text'] = esc_html(get_the_author_meta('display_name'));
	  $attribution['url'] = esc_url(get_permalink());
          break;

        case 'other': 
          $other = isset( $license['attribute_other'] ) ? $license['attribute_other'] : '';
          $other_url = isset( $license['attribute_other_url'] ) ? $license['attribute_other_url'] : '';
          
          $attribution['text'] = esc_html( $other );
          $attribution['url']  = esc_url( $other_url );
          break;
      }
      return $attribution; 
    }  
    
    function license_as_widget() {
      require_once('widgets/wplicense_widget.php');
      register_widget( 'WPLicense_widget' );
    }
  }
  $license = new WPLicense();
} else {
  $this->_logger('Could not instantiate class WPLicense due to already existing class WPLicense.'); 
}