Encapsulate the oEmbed -> oohembed fallback into oEmbedHelper class. Also added a chance to whitelist sites that don't show discovery info but do have oEmbed API endpoints, and to provide alternate APIs for some common services.

Newly supported:
- TwitPic: added a local function using TwitPic's API, since the oohembed implementation for TwitPic produced invalid output which Services_oEmbed rejects. (bug filed upstream)

Tweaked...
- Flickr: works, now using whitelist to use their endpoint directly instead of going through oohembed
- Youtube: worked around a bug in Services_oEmbed which broke the direct use of API discovery info, so we don't have to use oohembed.

Not currently working...
- YFrog: whitelisting their endpoint directly as the oohembed output is broken, but this doesn't appear to work currently as I think things are confused by YFrog's servers giving a '204 No Content' response on our HEAD checks on the original link.

2 files changed, 251 insertions, 15 deletions

diff --git a/classes/File_oembed.php b/classes/File_oembed.php
index bcb2f7bac..b7bf3a5da 100644
--- a/classes/File_oembed.php
+++ b/classes/File_oembed.php
@@ -59,25 +59,15 @@ class File_oembed extends Memcached_DataObject
     }
 
     function _getOembed($url) {
-        require_once INSTALLDIR.'/extlib/Services/oEmbed.php';
         $parameters = array(
             'maxwidth' => common_config('attachments', 'thumb_width'),
             'maxheight' => common_config('attachments', 'thumb_height'),
         );
-        try{
-            $oEmbed = new Services_oEmbed($url);
-            $object = $oEmbed->getObject($parameters);
-            return $object;
-        }catch(Exception $e){
-            try{
-                $oEmbed = new Services_oEmbed($url, array(
-                    Services_oEmbed::OPTION_API => common_config('oohembed', 'endpoint')
-                ));
-                $object = $oEmbed->getObject($parameters);
-                return $object;
-            }catch(Exception $ex){
-                return false;
-            }
+        try {
+            return oEmbedHelper::getObject($url, $parameters);
+        } catch (Exception $e) {
+            common_log(LOG_ERR, "Error during oembed lookup for $url - " . $e->getMessage());
+            return false;
         }
     }
 
diff --git a/lib/oembedhelper.php b/lib/oembedhelper.php
new file mode 100644
index 000000000..ef2b59214
--- /dev/null
+++ b/lib/oembedhelper.php
@@ -0,0 +1,246 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2008-2010, StatusNet, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.     See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.     If not, see <http://www.gnu.org/licenses/>.
+ */
+
+if (!defined('STATUSNET')) {
+    exit(1);
+}
+require_once INSTALLDIR.'/extlib/Services/oEmbed.php';
+
+
+/**
+ * Utility class to wrap Services_oEmbed:
+ *
+ * Blacklisted hosts will use an alternate lookup method:
+ *  - Twitpic
+ *
+ * Whitelisted hosts will use known oEmbed API endpoints:
+ *  - Flickr, YFrog
+ *
+ * Sites that provide discovery links will use them directly; a bug
+ * in use of discovery links with query strings is worked around.
+ *
+ * Others will fall back to oohembed (unless disabled).
+ * The API endpoint can be configured or disabled through config
+ * as 'oohembed'/'endpoint'.
+ */
+class oEmbedHelper
+{
+    protected static $apiMap = array(
+        'flickr.com' => 'http://www.flickr.com/services/oembed/',
+        'yfrog.com' => 'http://www.yfrog.com/api/oembed',
+    );
+    protected static $functionMap = array(
+        'twitpic.com' => 'oEmbedHelper::twitPic',
+    );
+
+    /**
+     * Perform or fake an oEmbed lookup for the given resource.
+     *
+     * Some known hosts are whitelisted with API endpoints where we
+     * know they exist but autodiscovery data isn't available.
+     * If autodiscovery links are missing and we don't recognize the
+     * host, we'll pass it to oohembed.com's public service which
+     * will either proxy or fake info on a lot of sites.
+     *
+     * A few hosts are blacklisted due to known problems with oohembed,
+     * in which case we'll look up the info another way and return
+     * equivalent data.
+     *
+     * Throws exceptions on failure.
+     *
+     * @param string $url
+     * @param array $params
+     * @return object
+     */
+    public static function getObject($url, $params=array())
+    {
+        common_log(LOG_INFO, 'QQQ: wtf? ' . $url);
+        $host = parse_url($url, PHP_URL_HOST);
+        if (substr($host, 0, 4) == 'www.') {
+            $host = substr($host, 4);
+        }
+
+        // Blacklist: systems with no oEmbed API of their own, which are
+        // either missing from or broken on oohembed.com's proxy.
+        // we know how to look data up in another way...
+        if (array_key_exists($host, self::$functionMap)) {
+            $func = self::$functionMap[$host];
+            return call_user_func($func, $url, $params);
+        }
+
+        // Whitelist: known API endpoints for sites that don't provide discovery...
+        if (array_key_exists($host, self::$apiMap)) {
+            $api = self::$apiMap[$host];
+            common_log(LOG_INFO, 'QQQ: going to: ' . $api);
+        } else {
+            $api = false;
+            common_log(LOG_INFO, 'QQQ: no map for ' . $host);
+        }
+        return self::getObjectFrom($api, $url, $params);
+    }
+
+    /**
+     * Actually do an oEmbed lookup to a particular API endpoint,
+     * or to the autodiscovered target, or to oohembed.
+     *
+     * @param mixed $api string or false: oEmbed API endpoint URL
+     * @param string $url target URL to look up info about
+     * @param array $params
+     * @return object
+     */
+    static protected function getObjectFrom($api, $url, $params=array())
+    {
+        $options = array();
+        if ($api) {
+            $options[Services_oEmbed::OPTION_API] = $api;
+        }
+
+        try {
+            $oEmbed = new Services_oEmbed_Tweaked($url, $options);
+        } catch (Services_oEmbed_Exception_NoSupport $e) {
+            // Discovery failed... fall back to oohembed if enabled.
+            $oohembed = common_config('oohembed', 'endpoint');
+            if ($oohembed) {
+                $options[Services_oEmbed::OPTION_API] = $oohembed;
+                $oEmbed = new Services_oEmbed_Tweaked($url, $options);
+            } else {
+                throw $e;
+            }
+        }
+
+        // And.... let's go look it up!
+        return $oEmbed->getObject($params);
+    }
+
+    /**
+     * Using a local function for twitpic lookups, as oohembed's adapter
+     * doesn't return a valid result:
+     * http://code.google.com/p/oohembed/issues/detail?id=19
+     *
+     * This code fetches metadata from Twitpic's own API, and attempts
+     * to guess proper thumbnail size from the original's size.
+     *
+     * @todo respect maxwidth and maxheight params
+     *
+     * @param string $url
+     * @param array $params
+     * @return object
+     */
+    static function twitPic($url, $params=array())
+    {
+        $matches = array();
+        if (preg_match('!twitpic\.com/(\w+)!', $url, $matches)) {
+            $id = $matches[1];
+        } else {
+            throw new Exception("Invalid twitpic URL");
+        }
+
+        // Grab metadata from twitpic's API...
+        // http://dev.twitpic.com/docs/2/media_show
+        $data = self::json('http://api.twitpic.com/2/media/show.json',
+                array('id' => $id));
+        $oembed = (object)array('type' => 'photo',
+                                'url' => 'http://twitpic.com/show/full/' . $data->short_id,
+                                'width' => $data->width,
+                                'height' => $data->height);
+        if (!empty($data->message)) {
+            $oembed->title = $data->message;
+        }
+
+        // Thumbnail is cropped and scaled to 150x150 box:
+        // http://dev.twitpic.com/docs/thumbnails/
+        $thumbSize = 150;
+        $oembed->thumbnail_url = 'http://twitpic.com/show/thumb/' . $data->short_id;
+        $oembed->thumbnail_width = $thumbSize;
+        $oembed->thumbnail_height = $thumbSize;
+
+        return $oembed;
+    }
+
+    /**
+     * Fetch some URL and return JSON data.
+     *
+     * @param string $url
+     * @param array $params query-string params
+     * @return object
+     */
+    static protected function json($url, $params=array())
+    {
+        $data = self::http($url, $params);
+        return json_decode($data);
+    }
+
+    /**
+     * Hit some web API and return data on success.
+     * @param string $url
+     * @param array $params
+     * @return string
+     */
+    static protected function http($url, $params=array())
+    {
+        $client = HTTPClient::start();
+        if ($params) {
+            $query = http_build_query($params, null, '&');
+            if (strpos($url, '?') === false) {
+                $url .= '?' . $query;
+            } else {
+                $url .= '&' . $query;
+            }
+        }
+        $response = $client->get($url);
+        if ($response->isOk()) {
+            return $response->getBody();
+        } else {
+            throw new Exception('Bad HTTP response code: ' . $response->getStatus());
+        }
+    }
+}
+
+class Services_oEmbed_Tweaked extends Services_oEmbed
+{
+    protected function discover($url)
+    {
+        $api = parent::discover($url);
+        if (strpos($api, '?') !== false) {
+            // Services_oEmbed doesn't expect to find existing params
+            // on its API endpoint, which may surprise you since the
+            // spec says discovery URLs should include parameters... :)
+            //
+            // Appending a '&' on the end keeps the later-appended '?'
+            // from breaking whatever the first parameters was.
+            return $api . '&';
+        }
+        return $api;
+    }
+
+    public function getObject(array $params = array())
+    {
+        $api = $this->options[self::OPTION_API];
+        if (strpos($api, '?') !== false) {
+            // The Services_oEmbed code appends a '?' on the end, which breaks
+            // the next parameter which may be something important like
+            // maxwidth.
+            //
+            // Sticking this bogus entry into our parameters gets us past it.
+            $params = array_merge(array('statusnet' => 1), $params);
+        }
+        return parent::getObject($params);
+    }
+
+}
\ No newline at end of file