<?php

defined( '_JEXEC' ) or die( 'Restricted access' );

jimport( 'joomla.plugin.plugin' );
class plgContentCanonical extends JPlugin
{
   function plgContentExample( &$subject, $params )
   {
      parent::__construct( $subject, $params );
   }
   function onPrepareContent( &$article, &$params, $limitstart )
   {
      global $mainframe;
      require_once(JPATH_SITE.DS.'components'.DS.'com_content'.DS.'helpers'.DS.'route.php');
      $alias1 = $article->id.'-';
      $alias1.= $article->alias;
      $articlecanonicalurl=JRoute::_( ContentHelperRoute::getArticleRoute( $alias1, $article->catslug, $article->sectionid));
      $canonical= '<link rel="canonical" href="'.$articlecanonicalurl.'" />';
      $document =& JFactory::getDocument();
      $document->addCustomTag($canonical);
   }

}