#4674 Add support for external medias: oembed, ogp, etc

main/inc/lib/autoload.class.php

@@ -69,6 +69,24 @@ class Autoload
         $result['AnnouncementEmail'] = '/main/announcements/announcement_email.class.php';
         $result['Answer'] = '/main/exercice/answer.class.php';
         $result['AppPlugin'] = '/main/inc/lib/plugin.lib.php';
+        $result['AssetAggregatedRenderer'] = '/main/inc/lib/external_media/renderer/asset_aggregated_renderer.class.php';
+        $result['AssetGoogleCalendarRenderer'] = '/main/inc/lib/external_media/renderer/lab/asset_google_calendar_renderer.class.php';
+        $result['AssetGoogleDocumentRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_google_document_renderer.class.php';
+        $result['AssetGoogleDocumentViewerRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_google_document_viewer_renderer.class.php';
+        $result['AssetGoogleMapRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_google_map_renderer.class.php';
+        $result['AssetGoogleWidgetRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_google_widget_renderer.class.php';
+        $result['AssetImageRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_image_renderer.class.php';
+        $result['AssetMaharaGroupRenderer'] = '/main/inc/lib/external_media/renderer/lab/asset_mahara_group_renderer.class.php';
+        $result['AssetMaharaPersonRenderer'] = '/main/inc/lib/external_media/renderer/lab/asset_mahara_person_renderer.class.php';
+        $result['AssetMediaRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_media_renderer.class.php';
+        $result['AssetMediaserverRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_mediaserver_renderer.class.php';
+        $result['AssetOembedRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_oembed_renderer.class.php';
+        $result['AssetOgRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_og_renderer.class.php';
+        $result['AssetPageRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_page_renderer.class.php';
+        $result['AssetRenderer'] = '/main/inc/lib/external_media/renderer/asset_renderer.class.php';
+        $result['AssetRssRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_rss_renderer.class.php';
+        $result['AssetScratchRenderer'] = '/main/inc/lib/external_media/renderer/protocol/asset_scratch_renderer.class.php';
+        $result['AssetWikiRenderer'] = '/main/inc/lib/external_media/renderer/lab/asset_wiki_renderer.class.php';
         $result['AttendanceLink'] = '/main/gradebook/lib/be/attendancelink.class.php';
         $result['Auth'] = '/main/inc/lib/auth.lib.php';
         $result['Block'] = '/main/dashboard/block.class.php';
@@ -211,6 +229,7 @@ class Autoload
         $result['HotSpotDelineation'] = '/main/exercice/hotspot.class.php';
         $result['Html'] = '/main/inc/lib/html.class.php';
         $result['Html_Quickform_Rule_Date'] = '/main/inc/lib/pear/HTML/QuickForm/Rule/Date.php';
+        $result['HttpResource'] = '/main/inc/lib/external_media/renderer/http_resource.class.php';
         $result['Image'] = '/main/inc/lib/image.lib.php';
         $result['ImageWrapper'] = '/main/inc/lib/image.lib.php';
         $result['ImagickWrapper'] = '/main/inc/lib/image.lib.php';
@@ -430,7 +449,6 @@ class Autoload
         $result['xhtdoc'] = '/main/inc/lib/xht.lib.php';
         $result['xmddoc'] = '/main/inc/lib/xmd.lib.php';
 
-
         return $result;
     }
 

main/inc/lib/external_media/renderer/__README.txt

@@ -0,0 +1 @@
+Used to extract metadata from external resources : youtube, dailymotion, etc

main/inc/lib/external_media/renderer/asset_aggregated_renderer.class.php

@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * Process all renderers attached in order.
+ * 
+ * If a renderer returns an key value that has not already been set add it
+ * to the result. Otherwise let the previous value unchanged.
+ *
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetAggregatedRenderer extends AssetRenderer
+{
+
+    protected $renderers = array();
+
+    public function __construct($renderers)
+    {
+        $this->renderers = $renderers;
+    }
+
+    /**
+     *
+     * @return array
+     */
+    public function renderers()
+    {
+        return $this->renderers;
+    }
+
+    /**
+     *
+     * @param HttpResource $asset
+     * @return array
+     */
+    public function render($asset)
+    {
+        $result = array();
+        $plugins = self::plugins();
+        foreach ($this->renderers as $renderer)
+        {
+            $data = $renderer->render($asset);
+            $data = $data ? $data : array();
+            foreach ($data as $key => $value)
+            {
+                if (!isset($result[$key]) && !empty($value))
+                {
+                    $result[$key] = $value;
+                }
+            }
+        }
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/asset_renderer.class.php

@@ -0,0 +1,107 @@
+<?php
+
+require_once dirname(__FILE__) . '/http_resource.class.php';
+require_once dirname(__FILE__) . '/asset_aggregated_renderer.class.php';
+
+/**
+ * Renderer for an http resource. 
+ * Extract meta data and snippet html view from an given url/resource.
+ * 
+ * Base class. Other renderers must inherit from it.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetRenderer
+{
+
+    const THUMBNAIL = 'thumbnail';
+    const EMBED_SNIPPET = 'embed_snippet';
+    const EMBED_TYPE = 'embed_type';
+    const EMBED_URL = 'embed_url';
+    const WIDTH = 'width';
+    const HEIGHT = 'height';
+    const LANGUAGE = 'language';
+    const URL = 'url';
+    const TAGS = 'tags';
+    const TITLE = 'title';
+    const CREATED_TIME = 'created_time';
+    const DURATION = 'duration';
+    const DESCRIPTION = 'description';
+    const ICON = 'icon';
+
+    static function get($url, $config = array())
+    {
+        if (strpos('url', 'javascript:') !== false)
+        {
+            return array();
+        }
+        $result = array();
+        $url = trim($url);
+        if (empty($url))
+        {
+            return array();
+        }
+        $asset = new HttpResource($url, $config);
+        $renderer = new AssetAggregatedRenderer(self::plugins());
+        $result = $renderer->render($asset);
+        $result['url'] = $url;
+        return $result;
+    }
+
+    static function plugins()
+    {
+        static $result = array();
+        if (!empty($result))
+        {
+            return $result;
+        }
+
+        /*
+         * We make sure we load them from most specialized to less specialized.
+         * The first that provides a value for a field wins.
+         */
+        $protocols = array(
+            'oembed',
+            'og',
+            'image',
+            'media',
+            'rss',
+            'google_map',
+            'google_document',
+            'google_document_viewer',
+            'google_widget',
+            'mediaserver',
+            'scratch',
+            'page');
+
+        foreach ($protocols as $protocol)
+        {
+            $file = "asset_{$protocol}_renderer.class.php";
+            require_once dirname(__FILE__) . '/protocol/' . $file;
+            
+            $class = "asset_{$protocol}_renderer";
+            $class = explode('_', $class);
+            $class = array_map('ucfirst', $class);
+            $class = implode($class);
+            
+            $result[] = new $class();
+        }
+        return $result;
+    }
+
+    /**
+     * Renderer function. Take a http asset as input and return an array containing
+     * various properties: metadata, html snippet, etc.
+     * 
+     * @param HttpResource $asset
+     * @return array
+     */
+    public function render($asset)
+    {
+        $result = array();
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/http_resource.class.php

@@ -0,0 +1,662 @@
+<?php
+
+/**
+ * An HTTP resource. In most cases an HTML document.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class HttpResource
+{
+
+    /**
+     * Fetch the content and metadata of an url. 
+     * 
+     * If the content type is not parsable, i.e. it is not made of text, 
+     * only fetch the metadata and not the content. This is mostly done to 
+     * avoid downloading big files - videos, images, etc - which is unnecessary.
+     * 
+     * @param string $url   the url to fetch
+     * @return array        array containing the content and various info
+     */
+    static function fetch($url, $fetch_content = null)
+    {
+        static $cache = array();
+        if (isset($cache[$url]))
+        {
+            return $cache;
+        }
+
+        if (is_null($fetch_content) || $fetch_content === false)
+        {
+            // create a new cURL resource
+            $ch = curl_init();
+
+            // set URL and other appropriate options
+            curl_setopt($ch, CURLOPT_URL, $url);
+            curl_setopt($ch, CURLOPT_HEADER, false);
+            curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+            curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
+            curl_setopt($ch, CURLOPT_NOBODY, true);
+
+            $content = curl_exec($ch);
+            $error = curl_error($ch);
+            $info = curl_getinfo($ch);
+
+            // close cURL resource, and free up system resources
+            curl_close($ch);
+            $info['content'] = $content;
+            $info['error'] = $error;
+
+            if ($fetch_content === false)
+            {
+                return $cache[$url] = $info;
+            }
+
+            if (isset($info['content_type']) && strpos($info['content_type'], 'text') === false)
+            {
+                return $cache[$url] = $info;
+            }
+        }
+
+        // create a new cURL resource
+        $ch = curl_init();
+
+        // set URL and other appropriate options
+        curl_setopt($ch, CURLOPT_URL, $url);
+        curl_setopt($ch, CURLOPT_HEADER, false);
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
+
+        //curl_setopt($ch, CURLOPT_VERBOSE, true);
+
+        $content = curl_exec($ch);
+        $error = curl_error($ch);
+        $info = curl_getinfo($ch);
+
+        // close cURL resource, and free up system resources
+        curl_close($ch);
+        $info['content'] = $content;
+        $info['error'] = $error;
+
+        return $cache[$url] = $info;
+    }
+
+    static function fetch_json($url)
+    {
+        $content = self::fetch($url, true);
+        $content = $content['content'];
+        if ($content)
+        {
+            $result = (array) json_decode($content);
+        }
+        else
+        {
+            $result = array();
+        }
+        return $result;
+    }
+
+    protected $url;
+    protected $url_params = null;
+    protected $info = null;
+    protected $source = null;
+    protected $metadata = null;
+    protected $links = null;
+    protected $title = null;
+    protected $mime = null;
+    protected $doc = null;
+    protected $config = array();
+
+    public function __construct($url, $config = array())
+    {
+        $this->url = $url;
+        $this->config = $config;
+    }
+
+    public function config($key = '', $default = null)
+    {
+        return isset($this->config[$key]) ? $this->config[$key] : $default;
+    }
+
+    /**
+     * Url of the resource
+     * 
+     * @return string
+     */
+    public function url()
+    {
+        return $this->url;
+    }
+
+    public function url_domain()
+    {
+        $url = $this->url();
+        $url = trim($url, '/');
+        if (strpos($url, '//') !== false)
+        {
+            $parts = explode('//', $url);
+            $url = end($parts);
+        }
+        $parts = explode('/', $url);
+        $result = reset($parts);
+        return $result;
+    }
+
+    /**
+     *
+     * @param array|string $part
+     * @return boolean 
+     */
+    public function url_match($part)
+    {
+        $params = func_get_args();
+        $params = is_array($params) ? $params : array($params);
+
+        $url = strtolower($this->url());
+        foreach ($params as $param)
+        {
+            if (strpos($url, strtolower($param)) !== false)
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public function url_params()
+    {
+        if (!is_null($this->url_params))
+        {
+            return $this->url_params;
+        }
+
+        $url = $this->url();
+        if (strpos($url, '?') === false)
+        {
+            return $this->url_params = array();
+        }
+
+        $result = array();
+        $params = explode('?', $url);
+        $params = end($params);
+        $params = explode('&', $params);
+        foreach ($params as $param)
+        {
+            list($key, $val) = explode('=', $param);
+            $result[$key] = $val;
+        }
+
+        return $this->url_params = $result;
+    }
+
+    public function url_param($name, $default = false)
+    {
+        $params = $this->url_params();
+        return isset($params[$name]) ? $params[$name] : $default;
+    }
+
+    /**
+     * The name of the resource. I.e. the last part of the url without the ext
+     * 
+     * @return string
+     */
+    public function name()
+    {
+        $url = $this->url();
+        $url = explode('/', $url);
+        $title = end($url);
+        $title = explode('.', $title);
+        $title = reset($title);
+        return $title;
+    }
+
+    /**
+     * Extention of the url
+     * 
+     * @return string
+     */
+    public function ext()
+    {
+        $url = $this->url();
+        $url = explode('.', $url);
+        $ext = end($url);
+        $ext = strtolower($ext);
+        return $ext;
+    }
+
+    /**
+     * Return true if the object has one of the extentions. Overloaded:
+     * 
+     *      $res->has_ext('pdf');
+     *      $res->has_ext('pdf', 'doc');
+     *      $res->has_ext(array('pdf', 'doc'));
+     * 
+     * @param array|string $_
+     * @return boolean true if the resource has one of the extentions passed
+     */
+    public function has_ext($_)
+    {
+        if (is_array($_))
+        {
+            $params = $_;
+        }
+        else
+        {
+            $params = func_get_args();
+            $params = is_array($params) ? $params : array($params);
+        }
+        $ext = $this->ext();
+        foreach ($params as $param)
+        {
+            if (strtolower($param) == $ext)
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public function charset()
+    {
+        $info = $this->info();
+
+        $content_type = isset($info['content_type']) ? $info['content_type'] : '';
+        if (empty($content_type))
+        {
+            return null;
+        }
+        $items = explode(';', $content_type);
+        foreach ($items as $item)
+        {
+            $parts = explode('=', $item);
+            if (count($parts) == 2 && reset($parts) == 'charset')
+            {
+                return strtolower(end($parts));
+            }
+        }
+        return null;
+    }
+
+    /**
+     * The mime type of the resource or the empty string if none has been specified
+     * 
+     * @return string
+     */
+    public function mime()
+    {
+        if (!is_null($this->mime))
+        {
+            return $this->mime;
+        }
+        $info = $this->info();
+
+        $content_type = isset($info['content_type']) ? $info['content_type'] : '';
+        if ($content_type)
+        {
+            $result = reset(explode(';', $content_type));
+            $result = strtolower($result);
+            return $this->mime = $result;
+        }
+
+        return $this->mime = '';
+    }
+
+    public function is_xml()
+    {
+        $mime = $this->mime();
+        if (!empty($mime))
+        {
+            return strpos($mime, 'xml') !== false;
+        }
+        return $this->ext() == 'xml';
+    }
+
+    public function is_image()
+    {
+        $mime = $this->mime();
+        if ($mime)
+        {
+            return strpos($mime, 'image') !== false;
+        }
+
+        $ext = $this->ext();
+        $formats = array('gif', 'jpeg', 'jpg', 'jpe', 'pjpeg', 'png', 'svg', 'tiff', 'ico');
+        foreach ($formats as $format)
+        {
+            if ($format == $ext)
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public function is_video()
+    {
+        $mime = $this->mime();
+        if ($mime)
+        {
+            return strpos($mime, 'video') !== false;
+        }
+
+        $ext = $this->ext();
+        $formats = array('mpeg', 'mp4', 'ogg', 'wmv', 'mkv');
+        foreach ($formats as $format)
+        {
+            if ($format == $ext)
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public function is_audio()
+    {
+        $mime = $this->mime();
+        if ($mime)
+        {
+            return strpos($mime, 'audio') !== false;
+        }
+
+        $ext = $this->ext();
+        $formats = array('mp3');
+        foreach ($formats as $format)
+        {
+            if ($format == $ext)
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public function is_rss()
+    {
+        if (!$this->is_xml())
+        {
+            return false;
+        }
+
+        $doc = $this->doc();
+        $nodes = $doc->getElementsByTagName('rss');
+        return $nodes->length != 0;
+    }
+
+    public function is_gadget()
+    {
+        if (!$this->is_xml())
+        {
+            return false;
+        }
+
+        $doc = $this->doc();
+        $nodes = $doc->getElementsByTagName('ModulePrefs');
+        return $nodes->length != 0;
+    }
+
+    public function canonic_url($src)
+    {
+        if (strpos($src, '//') === 0)
+        {
+            $src = "http:$src";
+        }
+        else if (strpos($src, '/') === 0) //relative url to the root 
+        {
+            $url = $this->url();
+            $protocol = reset(explode('://', $url));
+            $domain = end(explode('://', $url));
+            $domain = reset(explode('/', $domain));
+            $src = "$protocol://$domain/$src";
+        }
+        else if (strpos($src, 'http') !== 0) //relative url to the document
+        {
+            $url = $this->url();
+            $tail = end(explode('/', $url));
+            $base = str_replace($tail, '', $url);
+
+            $src = $base . $src;
+        }
+        return $src;
+    }
+
+    /**
+     * Content of the resource.
+     * 
+     * @return string
+     */
+    public function source()
+    {
+        if (!is_null($this->source))
+        {
+            return $this->source;
+        }
+        $info = $this->info();
+
+        return $this->source = $info['content'];
+    }
+
+    /**
+     * Array of arrays containing the page's metadata. 
+     * 
+     * @return array
+     */
+    public function metadata()
+    {
+        if (!is_null($this->metadata))
+        {
+            return $this->metadata;
+        }
+        return $this->metadata = $this->get_metadata();
+    }
+
+    public function title()
+    {
+        if (!is_null($this->title))
+        {
+            return $this->title;
+        }
+        return $this->title = $this->get_title();
+    }
+
+    /**
+     *
+     * @return DOMDocument|boolean
+     */
+    public function doc()
+    {
+        if (!is_null($this->doc))
+        {
+            return $this->doc;
+        }
+        return $this->doc = $this->get_doc($this->source());
+    }
+
+    function get_meta($name)
+    {
+        $metadata = $this->metadata();
+        $name = strtolower($name);
+        foreach ($metadata as $attributes)
+        {
+            $key = isset($attributes['name']) ? $attributes['name'] : false;
+            $key = $key ? strtolower($key) : $key;
+            if ($name == $key)
+            {
+                return $attributes['content'];
+            }
+            $key = isset($attributes['property']) ? $attributes['property'] : false;
+            $key = $key ? strtolower($key) : $key;
+            if ($name == $key)
+            {
+                return isset($attributes['content']) ? $attributes['content'] : false;
+            }
+        }
+        return false;
+    }
+
+    function get_link($key, $value)
+    {
+        $links = $this->links();
+        $key = strtolower($key);
+        $value = strtolower($value);
+        foreach ($links as $attributes)
+        {
+            $a = isset($attributes[$key]) ? $attributes[$key] : false;
+            $a = $a ? strtolower($a) : $a;
+            if ($a == $value)
+            {
+                return $attributes;
+            }
+        }
+        return false;
+    }
+
+    public function links()
+    {
+        if (!is_null($this->links))
+        {
+            return $this->links;
+        }
+        return $this->links = $this->get_links();
+    }
+
+    /**
+     *
+     * @param string $xpath dom xpath
+     * @return string
+     */
+    public function findx($query)
+    {
+        $doc = $this->doc();
+        if (empty($doc))
+        {
+            return array();
+        }
+        $xpath = new DOMXpath($doc);
+        $nodes = $xpath->query($query);
+        if ($nodes->length > 0)
+        {
+            return $doc->saveXML($nodes->item(0));
+        }
+        else
+        {
+            return '';
+        }
+    }
+
+    protected function info()
+    {
+        if (!is_null($this->info))
+        {
+            return $this->info;
+        }
+        return $this->info = self::fetch($this->url());
+    }
+
+    /**
+     *
+     * @param string $source
+     * @return boolean|DOMDocument 
+     */
+    protected function get_doc($source)
+    {
+        if ($source == false)
+        {
+            return false;
+        }
+        $source = $this->source();
+        $result = new DOMDocument();
+        libxml_clear_errors();
+        libxml_use_internal_errors(true);
+        if ($this->is_xml())
+        {
+            $success = $result->loadXML($source);
+        }
+        else
+        {
+            $success = $result->loadHTML($source);
+        }
+        //$e = libxml_get_errors();
+        return $result ? $result : false;
+    }
+
+    protected function get_metadata()
+    {
+        $result = array();
+
+        $doc = $this->doc();
+        if ($doc == false)
+        {
+            return array();
+        }
+        $metas = $doc->getElementsByTagName('meta');
+        if ($metas->length == 0)
+        {
+            return $result;
+        }
+        foreach ($metas as $meta)
+        {
+            $values = array();
+            $attributes = $meta->attributes;
+            $length = $attributes->length;
+            for ($i = 0; $i < $length; ++$i)
+            {
+                $name = $attributes->item($i)->name;
+                $value = $attributes->item($i)->value;
+                $value = $attributes->item($i)->value;
+                $values[$name] = $value;
+            }
+            $result[] = $values;
+        }
+        return $result;
+    }
+
+    protected function get_title()
+    {
+        $doc = $this->doc();
+        if ($doc == false)
+        {
+            return '';
+        }
+        $titles = $doc->getElementsByTagName('title');
+        if ($titles->length == 0)
+        {
+            return false;
+        }
+        $result = $titles->item(0)->nodeValue;
+        return $result;
+    }
+
+    protected function get_links()
+    {
+        $doc = $this->doc();
+        if ($doc == false)
+        {
+            return array();
+        }
+        $result = array();
+
+        $metas = $doc->getElementsByTagName('link');
+        if ($metas->length == 0)
+        {
+            return $result;
+        }
+        foreach ($metas as $meta)
+        {
+            $values = array();
+            $attributes = $meta->attributes;
+            $length = $attributes->length;
+            for ($i = 0; $i < $length; ++$i)
+            {
+                $name = $attributes->item($i)->name;
+                $value = $attributes->item($i)->value;
+                $values[$name] = $value;
+            }
+            $result[] = $values;
+        }
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/lab/asset_google_calendar_renderer.class.php

@@ -0,0 +1,113 @@
+<?php
+
+/**
+ * Google calendar renderer. 
+ * 
+ * @todo: 
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetGoogleCalendarRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {
+        $url = $asset->url();
+        $url = str_replace('http://', '', $url);
+        $url = str_replace('https://', '', $url);
+
+        $domain = reset(split('/', $url));
+        return strpos($domain, 'google.com/calendar') !== false;
+    }
+
+    /**
+     *
+     * @param string $url 
+     */
+    public function explode_url_parameters($url = null)
+    {
+        if (strpos($url, '?') === false)
+        {
+            return array();
+        }
+
+        $result = array();
+        $params = explode('?', $url);
+        $params = end($params);
+        $params = explode('&', $params);
+        foreach ($params as $param)
+        {
+            list($key, $val) = explode('=', $param);
+            $result[$key] = $val;
+        }
+
+        return $result;
+    }
+
+    public function implode_url_parameters($params)
+    {
+        $result = array();
+        foreach ($params as $key => $value)
+        {
+            if ($value)
+            {
+                $result[] = "$key=$value";
+            }
+        }
+        return join('&', $result);
+    }
+
+    protected function url($base = 'http:://map.google.com/', $params = array())
+    {
+        $head = reset(explode('?', $base));
+        $items = $this->explode_url_parameters($base);
+        foreach ($params as $key => $value)
+        {
+                $items[$key] = $value;
+        }
+        $tail = $this->implode_url_parameters($items);
+        $tail = empty($tail) ? '' : "?$tail";
+        return $head . $tail;
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+        $params = array('output' => 'embed');
+        
+        $base = $asset->url();
+        $url = $this->url($base, $params);
+        
+        $title = $asset->title();
+        $description = $asset->get_meta('description');
+
+        $keywords = $asset->get_meta('keywords');
+
+        $embed = <<<EOT
+        <iframe width="100%" height="350" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="$url"></iframe>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        $result[self::THUMBNAIL] = $image_src;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/lab/asset_mahara_group_renderer.class.php

@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * Internal group. I.e. a group from this instance of Mahara.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetMaharaGroupRenderer extends AssetRenderer
+{
+
+    public static function get_group_id($ref)
+    {
+        $ref = trim($ref);
+        $pattern = '#group/view.php\?id\=([0123456789]+)#';
+        $matches = array();
+        //mahara group's profile
+        if (preg_match($pattern, $ref, $matches))
+        {
+            return $matches[1];
+        }
+        //group id
+        if ($val = intval($ref))
+        {
+            return $val;
+        }
+
+        return false;
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        $url = $asset->url();
+        $group_id = self::get_group_id($url);
+        if (empty($group_id))
+        {
+            return false;
+        }
+
+        $data = get_record('group', 'id', $group_id);
+
+        $result = array();
+        safe_require('blocktype', 'ple/group');
+        $result[self::EMBED_SNIPPET] = PluginBlocktypeGroup::render_preview($group_id);
+        $result[self::THUMBNAIL] = PluginBlocktypeGroup::get_thumbnail($group_id);
+        $result[self::TITLE] = $data->name;
+        $result[self::DESCRIPTION] = $data->description;
+
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/lab/asset_mahara_person_renderer.class.php

@@ -0,0 +1,63 @@
+<?php
+
+/**
+ *
+ * Internal person. I.e. a person from this instance of Mahara.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetMaharaPersonRenderer extends AssetRenderer
+{
+
+    public static function get_user_id($ref)
+    {
+        $ref = trim($ref);
+        $pattern = '#user/view.php\?id\=([0123456789]+)#';
+        $matches = array();
+        //mahara user's profile
+        if (preg_match($pattern, $ref, $matches))
+        {
+            return $matches[1];
+        }
+        //email
+        if ($user = get_record('usr', 'email', $ref))
+        {
+            return $user->id;
+        }
+        //user id
+        if ($val = intval($ref))
+        {
+            return $val;
+        }
+
+        return false;
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        $url = $asset->url();
+        $id = self::get_user_id($url);
+        if (empty($id))
+        {
+            return false;
+        }
+
+        $data = get_record('usr', 'id', $id);
+
+        $result = array();
+        safe_require('blocktype', 'ple/person');
+        $result[self::EMBED_SNIPPET] = PluginBlocktypePerson::render_preview($id);
+        $result[self::THUMBNAIL] = PluginBlocktypePerson::get_thumbnail($id);
+        $result[self::TITLE] = $data->prefferedname ? $data->prefferedname : $data->firstname . ' ' . $data->lastname;
+        $result[self::DESCRIPTION] = isset($data->description) ? $data->description : '';
+
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/lab/asset_wiki_renderer.class.php

@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * Wiki renderer. 
+ * 
+ * @see http://en.wikipedia.org/w/api.php
+ * 
+ * @copyright (c) 2012 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetWikiRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {       
+        return $asset->url_match('wikipedia.org/wiki', 'mediawiki.org/wiki');
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     * 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $domain = $asset->url_domain();
+        $description = $asset->findx('//div[@id="bodyContent"]/p');
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $description;
+        $result[self::TITLE] = $title;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_google_document_renderer.class.php

@@ -0,0 +1,75 @@
+<?php
+
+/**
+ * Google document renderer. 
+ * 
+ * @see http://support.google.com/docs/bin/answer.py?hl=en&answer=86101&topic=1360911&ctx=topic
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetGoogleDocumentRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {       
+        $url = $asset->url();
+        
+        return strpos($url, 'docs.google.com/document/pub') !== false;
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $url = $asset->url();
+
+        $title = $asset->title();
+        $description = $asset->get_meta('description');
+        $keywords = $asset->get_meta('keywords');
+        
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+
+        $embed = <<<EOT
+        
+        <div style="height:{$size}px;" class="resize vertical" >
+            <iframe style=background-color:#ffffff;" width="100%" height="100%" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="$url"></iframe>
+        </div>
+        <style type="text/css">
+        div.resize.vertical {
+            background-color: #EEEEEE;
+            border-color: #EEEEEE;
+            border-style: solid;
+            border-width: 1px;
+            resize:vertical;
+            overflow: hidden; 
+            padding-bottom:15px; 
+            min-height:24px; 
+            max-height:800px;
+}
+        </style>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_google_document_viewer_renderer.class.php

@@ -0,0 +1,95 @@
+<?php
+
+/**
+ * Google document viewer renderer. Provide an embeded viewer for the following
+ * documetn types:
+ * 
+ *     Microsoft Word (.DOC and .DOCX)
+ *     Microsoft Excel (.XLS and .XLSX)
+ *     Microsoft PowerPoint (.PPT and .PPTX)
+ *     Adobe Portable Document Format (.PDF)
+ *     Apple Pages (.PAGES)
+ *     Adobe Illustrator (.AI)
+ *     Adobe Photoshop (.PSD)
+ *     Tagged Image File Format (.TIFF)
+ *     Autodesk AutoCad (.DXF)
+ *     Scalable Vector Graphics (.SVG)
+ *     PostScript (.EPS, .PS)
+ *     TrueType (.TTF)
+ *     XML Paper Specification (.XPS)
+ *     Archive file types (.ZIP and .RAR)
+ * 
+ * @see https://docs.google.com/viewer
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetGoogleDocumentViewerRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {
+        $supported_extentions = array('doc', 'docx', 'xls', 'xlsx', 'ppt', 'pptx', 'pdf', 'pages', 'ai', 'psd', 'tiff', 'dxf', 'svg', 'eps', 'ps', 'eps', 'ttf', 'zip', 'rar');
+        return $asset->has_ext($supported_extentions);
+    }
+
+    protected function url($document_url)
+    {
+        return 'https://docs.google.com/viewer?embedded=true&url=' . urlencode($document_url);
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $url = $this->url($asset->url());
+
+        $title = $asset->title();
+        $description = $asset->get_meta('description');
+
+        $keywords = $asset->get_meta('keywords');
+
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+
+        $embed = <<<EOT
+        <div style="height:{$size}px;" class="resize vertical" >
+            <iframe style=background-color:#ffffff;" width="100%" height="100%" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="$url"></iframe>
+        </div>
+        <style type="text/css">
+        div.resize.vertical {
+            background-color: #EEEEEE;
+            border-color: #EEEEEE;
+            border-style: solid;
+            border-width: 1px;
+            resize:vertical;
+            overflow: hidden; 
+            padding-bottom:15px; 
+            min-height:24px; 
+            max-height:800px;
+}
+        </style>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        //$result[self::THUMBNAIL] = $image_src;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_google_map_renderer.class.php

@@ -0,0 +1,129 @@
+<?php
+
+/**
+ * Google map page renderer. 
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetGoogleMapRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {
+        $url = $asset->url();
+        $url = str_replace('http://', '', $url);
+        $url = str_replace('https://', '', $url);
+
+        $domain = reset(explode('/', $url));
+        return strpos($domain, 'maps.google') !== false;
+    }
+
+    /**
+     *
+     * @param string $url 
+     */
+    public function explode_url_parameters($url = null)
+    {
+        if (strpos($url, '?') === false)
+        {
+            return array();
+        }
+
+        $result = array();
+        $params = explode('?', $url);
+        $params = end($params);
+        $params = explode('&', $params);
+        foreach ($params as $param)
+        {
+            list($key, $val) = explode('=', $param);
+            $result[$key] = $val;
+        }
+
+        return $result;
+    }
+
+    public function implode_url_parameters($params)
+    {
+        $result = array();
+        foreach ($params as $key => $value)
+        {
+            if ($value)
+            {
+                $result[] = "$key=$value";
+            }
+        }
+        return join('&', $result);
+    }
+
+    protected function url($base = 'http:://map.google.com/', $params = array())
+    {
+        $head = reset(explode('?', $base));
+        $items = $this->explode_url_parameters($base);
+        foreach ($params as $key => $value)
+        {
+                $items[$key] = $value;
+        }
+        $tail = $this->implode_url_parameters($items);
+        $tail = empty($tail) ? '' : "?$tail";
+        return $head . $tail;
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $params = array('output' => 'embed');
+        
+        $base = $asset->url();
+        $url = $this->url($base, $params);
+        
+        $title = $asset->title();
+        $description = $asset->get_meta('description');
+
+        $keywords = $asset->get_meta('keywords');
+        
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+
+        $embed = <<<EOT
+        <div style="height:{$size}px;" class="resize vertical" >
+            <iframe style=background-color:#ffffff;" width="100%" height="100%" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="$url"></iframe>
+        </div>
+        <style type="text/css">
+        div.resize.vertical {
+            background-color: #EEEEEE;
+            border-color: #EEEEEE;
+            border-style: solid;
+            border-width: 1px;
+            resize:vertical;
+            overflow: hidden; 
+            padding-bottom:15px; 
+            min-height:24px; 
+            max-height:800px;
+}
+        </style>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_google_widget_renderer.class.php

@@ -0,0 +1,90 @@
+<?php
+
+/**
+ * Google widget/gadget renderer.
+ * Accept the following urls:
+ * 
+ *      module:             http://www.google.com/ig/directory?type=gadgets&url=www.google.com/ig/modules/eyes/eyes.xml
+ *      directory entry:    www.google.com/ig/modules/eyes/eyes.xml
+ *      configured url:     www.gmodules.com/ig/ifr?url=http://www.google.com/ig/modules/eyes/eyes.xml&amp;synd=open&amp;w=320&amp;h=121&amp;title=__MSG_title__&amp;lang=fr&amp;country=ALL&amp;border=%23ffffff%7C3px%2C1px+solid+%23999999&amp;output=js
+ * 
+ * @see http://www.google.com/ig/directory?type=gadgets&url=www.google.com/ig/modules/eyes/eyes.xml
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetGoogleWidgetRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        
+        if ($asset->url_match('gmodules.com/ig/') && $asset->url_param('url') != false)
+        {
+            $url = $asset->url();
+            $title = $asset->url_param('title');
+            $title = ($title == '__MSG_title__') ? '' : $title;
+            
+            $embed = <<<EOT
+                <script src="$url"></script>
+EOT;
+            
+            $result = array();
+            $result[self::EMBED_SNIPPET] = $embed;
+            $result[self::TITLE] = $title;
+            return $result;
+        }
+
+        if (!$asset->is_gadget())
+        {
+            $url = $asset->url();
+
+            if (!$asset->url_match('google.com/ig/directory'))
+            {
+                return false;
+            }
+            if (!$asset->url_match('type=gadgets'))
+            {
+                return false;
+            }
+
+            $url = $asset->url_param('url');
+            if (empty($url))
+            {
+                return false;
+            }
+            $asset = new HttpResource($url);
+            if (!$asset->is_gadget())
+            {
+                return false;
+            }
+        }
+
+        $url = $asset->url();
+        if (strpos($url, 'http') !== 0)
+        {
+            $url = "http://$url";
+        }
+        $url = urlencode($url);
+        $title = $asset->title();
+        $title = $title ? $title : $asset->name();
+        
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+
+        $embed = <<<EOT
+        <script src="//www.gmodules.com/ig/ifr?url=$url&amp;w=$size&amp;output=js"></script>
+EOT;
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_image_renderer.class.php

@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * Process image resources. I.e. png, jpeg, etc.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetImageRenderer extends AssetRenderer
+{
+    
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (! $asset->is_image())
+        {
+            return false;
+        }
+        
+        global $THEME;
+        $url = $asset->url();
+        $title = $asset->title();
+        $title = $title ? $title : $asset->name();
+        
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+        
+        $embed = <<<EOT
+        <div style="text-align:center"><a href="$url"><img src="{$url}" width="$size" alt="{$title}" title="{$title}"></a></div>
+EOT;
+
+        $result = array();
+        $result[self::URL] = $url;
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        $result[self::THUMBNAIL] = $url;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_media_renderer.class.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * Media renderer. I.e. video streams that can be embeded through an embed tag.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetMediaRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {
+        if ($asset->is_video())
+        {
+            return true;
+        }
+        
+        //swf mime type is application/x-shockwave-flash
+        return $asset->has_ext('swf');
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $url = $asset->url();
+
+        $title = $asset->title();
+        $description = $asset->get_meta('description');
+        $keywords = $asset->get_meta('keywords');
+        
+        
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+        
+        $width = $size;
+        $height = $size *9/16;
+
+        $embed = <<<EOT
+        <div style="text-align:center;"><embed style="display:inline-block;" width="{$width}px" height="{$height}px" name="plugin" src="$url" ></div>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_mediaserver_renderer.class.php

@@ -0,0 +1,65 @@
+<?php
+
+/**
+ * Media Server renderer. 
+ * 
+ * Note that some videos are protected. It is therefore not possible to use the
+ * autodiscovery feature. That is to get the web page, look at the meta data headers
+ * and read the oembed api call. This would only work for public content/javascript
+ * bookmarklet. 
+ * 
+ * So here we bypass the discovery service and directly call the API endpoint 
+ * with the page url to retrieve oembed metadata - which happens to be public.
+ * 
+ * @see https://mediaserver.unige.ch
+ * 
+ * @copyright (c) 2012 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetMediaserverRenderer extends AssetRenderer
+{
+    
+    const API_ENDPOINT = 'http://129.194.20.121/oembed/unige-oembed-provider-test.php';
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {
+        return $asset->url_match('https://mediaserver.unige.ch/play/') ||$asset->url_match('http://mediaserver.unige.ch/play/');
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $width = (int) $asset->config('size');
+        $width = (24 <= $width && $width <= 800) ? $width : 300;
+        
+        $url = $asset->url();
+        
+        $oembed = self::API_ENDPOINT . '?url=' . urlencode($url) . '&maxwidth=' . $width;
+
+        $data = HttpResource::fetch_json($oembed); 
+        if (empty($data))
+        {
+            return false;
+        }
+
+        $result[self::THUMBNAIL] = isset($data['thumbnail_url']) ? $data['thumbnail_url'] : '';
+        $result[self::TITLE] = isset($data['title']) ? $data['title'] : '';
+        $result[self::EMBED_SNIPPET] = isset($data['html']) ? $data['html'] : '';
+
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_oembed_renderer.class.php

@@ -0,0 +1,124 @@
+<?php
+
+/**
+ * Process html pages that support the oembed protocol.
+ * 
+ * Note that here we rely on the discovery service. That is each page that contains in
+ * its metadata the oembed request.
+ * 
+ * @see http://oembed.com/
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ * 
+ */
+class AssetOembedRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        $link = $asset->get_link('type', 'application/json+oembed');
+        if (empty($link))
+        {
+            return false;
+        }
+
+        $width = (int) $asset->config('size');
+        $width = (24 <= $width && $width <= 800) ? $width : 300;
+
+        $href = $link['href'];
+        $data = HttpResource::fetch_json("$href&maxwidth=$width"); //&maxheight=$height
+        if (empty($data))
+        {
+            return false;
+        }
+
+        $data['title'] = isset($data['title']) ? $data['title'] : '';
+        $data['width'] = isset($data['width']) ? intval($data['width']) : '';
+        $data['height'] = isset($data['height']) ? intval($data['height']) : '';
+
+        $type = $data['type'];
+        $f = array($this, "render_$type");
+        if (is_callable($f))
+        {
+            $result = call_user_func($f, $asset, $data);
+        }
+        else
+        {
+            $result = array();
+        }
+        $result[self::THUMBNAIL] = isset($data['thumbnail_url']) ? $data['thumbnail_url'] : '';
+        $result[self::TITLE] = isset($data['title']) ? $data['title'] : '';
+
+        return $result;
+    }
+
+    protected function render_photo($asset, $data)
+    {
+        if ($data['type'] != 'photo')
+        {
+            return array();
+        }
+
+        $result = array();
+        $html = isset($data['html']) ? $data['html'] : '';
+        if ($html)
+        {
+            $result[self::EMBED_SNIPPET] = '<div style="display:inline-block">' . $html . '</div>';
+            return $result;
+        }
+
+        $title = $data['title'];
+        $width = (int)$data['width'];
+        $height = (int)$data['height'];
+//        $ratio = $height / $width;
+//        $height = $ratio * $width;
+
+        $url = $data['url'];
+
+        $embed = <<<EOT
+        <div><a href="$url"><img src="{$url}" width="{$width}" height="{$height}" "alt="{$title}" title="{$title}"></a></div>
+EOT;
+
+        $result[self::EMBED_SNIPPET] = $embed;
+        return $result;
+    }
+
+    protected function render_video($asset, $data)
+    {
+        if ($data['type'] != 'video')
+        {
+            return array();
+        }
+        $result = array();
+        $result[self::EMBED_SNIPPET] = '<div style="display:inline-block">' . $data['html'] . '</div>';
+        return $result;
+    }
+
+    protected function render_rich($asset, $data)
+    {
+        if ($data['type'] != 'rich')
+        {
+            return array();
+        }
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = '<div style="display:inline-block">' . $data['html'] . '</div>';
+        return $result;
+    }
+
+    protected function render_link($asset, $data)
+    {
+        if ($data['type'] != 'link')
+        {
+            return array();
+        }
+        return array();
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_og_renderer.class.php

@@ -0,0 +1,201 @@
+<?php
+
+/**
+ * Process pages that support the open graph protocol
+ * 
+ * @see http://ogp.me/
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetOgRenderer extends AssetRenderer
+{
+
+    /**
+     * Renderer function. Take a http asset as input and return an array containing
+     * various properties: metadata, html snippet, etc.
+     * 
+     * @param HttpResource $asset
+     * @return array
+     */
+    public function render($asset)
+    {
+        $type = $asset->get_meta('og:type');
+        if (empty($type))
+        {
+            if ($video = $asset->get_meta('og:video'))
+            {
+                $type = 'video';
+            }
+            else if ($video = $asset->get_meta('og:image'))
+            {
+                $type = 'default';
+            }
+        }
+        if (empty($type))
+        {
+            return array();
+        }
+
+        $type = explode('.', $type);
+        $type = reset($type);
+        $f = array($this, "render_$type");
+        if (is_callable($f))
+        {
+            $result = call_user_func($f, $asset);
+        }
+        else
+        {
+            $result = $this->render_default($asset);
+        }
+
+        $result[self::TITLE] = $asset->get_meta('og:title');
+        $result[self::THUMBNAIL] = $asset->get_meta('og:image');
+        $result[self::LANGUAGE] = $asset->get_meta('og:language');
+
+        return $result;
+    }
+
+    /**
+     * @param HttpResource $asset
+     * @return array
+     */
+    protected function render_video($asset)
+    {
+        $url = $asset->get_meta('og:video');
+        $url = str_replace('?autoPlay=1', '?', $url);
+        $url = str_replace('&autoPlay=1', '', $url);
+
+        if (empty($url))
+        {
+            return array();
+        }
+
+        $type = $asset->get_meta('og:video:type');
+        if ($type)
+        {
+            $type = ' type="' . $type . '" ';
+        }
+        
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+        
+        $width = $asset->get_meta('og:video:width');
+        $width = $width ? $width : $asset->get_meta('video_width');
+        $height = $asset->get_meta('og:video:height');
+        $height = $height ? $height : $asset->get_meta('video_height');
+
+        if ($width)
+        {
+            $ratio = $height / $width;
+            $base = min($size, $width);
+            $width = $base;
+            $height = $ratio * $base;
+            $size = 'width="' . $width . '" height="' . $height . '"';
+        }
+        else
+        {
+            $size = 'width="' . $size . '"';
+        }
+
+        $embed = <<<EOT
+        <embed $type $size src="$url" />        
+EOT;
+
+        $result[self::EMBED_TYPE] = $type;
+        $result[self::EMBED_URL] = $url;
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TAGS] = $asset->get_meta('og:video:tag');
+        $result[self::CREATED_TIME] = $asset->get_meta('og:video:release_date');
+        $result[self::DURATION] = $asset->get_meta('og:duration');
+        return $result;
+    }
+
+    protected function render_article($asset)
+    {
+        $result = $this->render_default($asset);
+        return $result;
+    }
+
+    protected function render_audio($asset)
+    {
+        $result = $this->render_default($asset);
+        return $result;
+    }
+
+    protected function render_book($asset)
+    {
+        $result = $this->render_default($asset);
+        return $result;
+    }
+
+    /**
+     * 
+     * @param HttpResource $asset
+     * @return array
+     */
+    protected function render_default($asset)
+    {
+        $url = $asset->get_meta('og:url');
+        $url = htmlentities($url);
+        $title = $asset->get_meta('og:title');
+        $image = $asset->get_meta('og:image');
+        $image = htmlentities($image);
+        $width = $asset->get_meta('og:image:width');
+        $height = $asset->get_meta('og:image:height');
+        $description = $asset->get_meta('og:description');
+        $description = $description ? $description : $asset->get_meta('description');
+
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+
+        if ($width)
+        {
+            $ratio = $height / $width;
+            $base = min($size, $width);
+            $width = $base;
+            $height = $ratio * $base;
+            $size = 'width="' . $width . '" height="' . $height . '"';
+        }
+        else
+        {
+            $size = 'width="' . $size . '"';
+        }
+        $embed = <<<EOT
+        <div>
+            <a href="$url" style="float:left; margin-right:5px; margin-bottom:5px; display:block;"><img src="{$image}" {$size} alt="{$title}" title="{$title}"></a>
+            <div style="clear:both;"></div>
+        </div>
+EOT;
+
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::DESCRIPTION] = $asset->get_meta('description');
+        return $result;
+    }
+
+    /**
+     * @param HttpResource $asset
+     * @return array
+     */
+    protected function render_image($asset)
+    {
+        $size = (int) $asset->config('size');
+        $size = (24 <= $size && $size <= 800) ? $size : 300;
+
+        $title = $data['title'];
+        $width = $data['width'];
+        $height = $data['height'];
+        $ratio = $height / $width;
+        $base = min($size, $width);
+        $width = $base;
+        $height = $ratio * $base;
+
+        $url = $data['url'];
+
+        $embed = <<<EOT
+        <a href="$url"><img src="{$url}" width="{$width}" height="{$height} "alt="{$title}" title="{$title}"></a>
+EOT;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_page_renderer.class.php

@@ -0,0 +1,83 @@
+<?php
+
+/**
+ * Generic HTML page renderer. Process any html page.
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetPageRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        global $THEME;
+        $url = $asset->url();
+        $title = $asset->title();
+        $title = $title ? $title : $asset->name();
+        $description = $asset->get_meta('description');
+        $description = $description;
+
+        $keywords = $asset->get_meta('keywords');
+
+        $image_src = $asset->get_link('rel', 'image_src');
+        $image_src = $image_src ? $image_src['href'] : false;
+
+        if (empty($image_src))
+        {
+            $image_src = $this->get_icon($asset);
+        }
+
+        $icon = $this->get_icon($asset);
+        
+        $image_src = $asset->canonic_url($image_src);
+        $icon = $asset->canonic_url($icon);
+
+        $embed = <<<EOT
+        <a href="$url">
+            <img src="{$image_src}" alt="{$title}" title="{$title}" style="float:left; margin-right:5px; margin-bottom:5px; " >
+        </a>
+        $description
+        <span style="clear:both;"></span>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        $result[self::THUMBNAIL] = $image_src;
+        $result[self::DESCRIPTION] = $description;
+        $result[self::ICON] = $icon;
+        $result[self::TAGS] = $keywords;
+        return $result;
+    }
+
+    function get_icon($asset)
+    {
+
+        $icon = $asset->get_link('rel', 'apple-touch-icon');
+        $icon = $icon ? $icon['href'] : false;
+        if (empty($icon))
+        {
+            $icon = $asset->get_link('rel', 'fluid-icon');
+            $icon = $icon ? $icon['href'] : false;
+        }
+        if (empty($icon))
+        {
+            $icon = $asset->get_link('rel', 'shortcut icon');
+            $icon = $icon ? $icon['href'] : false;
+        }
+        if (empty($icon))
+        {
+            $icon = $asset->get_link('rel', 'icon');
+            $icon = $icon ? $icon['href'] : false;
+        }
+        return $icon;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_rss_renderer.class.php

@@ -0,0 +1,95 @@
+<?php
+
+/**
+ * Rss renderer. Display RSS thanks to Google feed control.
+ * 
+ * @see http://www.google.com/uds/solutions/dynamicfeed/reference.html
+ * @see http://code.google.com/apis/ajax/playground/#dynamic_feed_control_-_vertical
+ * 
+ * @copyright (c) 2011 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetRssRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$asset->is_rss())
+        {
+            return;
+        }
+
+        $url = $asset->url();
+        $title = $asset->title();
+        $id = 'a' . md5($url);
+
+        $embed = <<<EOT
+        <style type="text/css">
+            .gfg-root {
+                border: none;
+                font-family: inherit;
+            }
+        </style>
+        <script type="text/javascript" src="http://www.google.com/jsapi"></script>
+        <script src="http://www.google.com/uds/solutions/dynamicfeed/gfdynamicfeedcontrol.js" type="text/javascript"></script> 
+        <script type="text/javascript">
+        
+            function init()
+            {
+                if (typeof this.has_run == 'undefined' )
+                {
+                    this.has_run = true;
+                }
+                else
+                {
+                    return;
+                }
+                var head = document.getElementsByTagName('head')[0];
+        
+                var element = document.createElement('link');
+                element.type = 'text/css';
+                element.rel = 'stylesheet';
+                element.href = 'http://www.google.com/uds/solutions/dynamicfeed/gfdynamicfeedcontrol.css';
+                head.appendChild(element);
+            }
+
+            function load_$id() {
+                var feeds = [
+                    {
+                    title: ' ',
+                    url: '$url'
+                    }
+                ];
+
+                var options = {
+                    stacked : false,
+                    horizontal : false,
+                    title : '',
+                    numResults : 10
+                };
+
+                new GFdynamicFeedControl(feeds, '$id', options);
+                document.getElementById('content').style.width = "500px";
+            }
+        
+        
+            init();
+            google.load('feeds', '1');
+            google.setOnLoadCallback(load_$id);
+       </script>        
+       <div id="$id" style="min-height:271px;">Loading...</div>
+EOT;
+
+
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::TITLE] = $title;
+        return $result;
+    }
+
+}

main/inc/lib/external_media/renderer/protocol/asset_scratch_renderer.class.php

@@ -0,0 +1,76 @@
+<?php
+
+/**
+ * Scratch renderer. 
+ * 
+ * @see http://scratch.mit.edu/projects/
+ * 
+ * @copyright (c) 2012 University of Geneva
+ * @license GNU General Public License - http://www.gnu.org/copyleft/gpl.html
+ * @author Laurent Opprecht
+ */
+class AssetScratchRenderer extends AssetRenderer
+{
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function accept($asset)
+    {
+        return $asset->url_match('http://scratch.mit.edu/projects/');
+    }
+
+    /**
+     *
+     * @param HttpResource $asset 
+     */
+    public function render($asset)
+    {
+        if (!$this->accept($asset))
+        {
+            return;
+        }
+
+        $matches = array();
+        $pattern = "#http:\/\/scratch.mit.edu\/projects\/(\w+)/(\d*)\/?#ims";
+        preg_match($pattern, $asset->url(), $matches);
+
+        $url = $matches[0];
+        $author = $matches[1];
+        $project_id = $matches[2];
+
+        $project_url = "../../static/projects/$author/$project_id.sb";
+        $image_url = "http://scratch.mit.edu/static/projects/$author/{$project_id}_med.png";
+        $thumb_url = "http://scratch.mit.edu/static/projects/$author/{$project_id}_sm.png";
+
+        $height = 387;
+        $width = 482;
+
+        if (function_exists('get_string'))
+        {
+            $no_java = get_string('no_java', 'artefact.extresource');
+        }
+        else
+        {
+            $no_java = 'Java is not installed on your computer. You must install java first.';
+        }
+
+        $embed = <<<EOT
+        <object type="application/x-java-applet" width="$width" height="$height"  style="display:block" id="ProjectApplet">
+
+            <param name="codebase" value="http://scratch.mit.edu/static/misc">
+            <param name="archive" value="ScratchApplet.jar">
+            <param name="code" value="ScratchApplet">
+            <param name="project" value="$project_url">
+            <pre>$no_java</pre>
+            <img alt="" src="$image_url">
+        </object>
+EOT;
+        $result = array();
+        $result[self::EMBED_SNIPPET] = $embed;
+        $result[self::THUMBNAIL] = $thumb_url;
+        return $result;
+    }
+
+}