gnu-social/lib/oembedhelper.php

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<?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);
}
/**
* Utility class to wrap basic oEmbed lookups.
*
* 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())
{
$host = parse_url($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];
} else {
try {
$api = self::discover($url);
} catch (Exception $e) {
// Discovery failed... fall back to oohembed if enabled.
$oohembed = common_config('oohembed', 'endpoint');
if ($oohembed) {
$api = $oohembed;
} else {
throw $e;
}
}
}
return self::getObjectFrom($api, $url, $params);
}
/**
* Perform basic discovery.
* @return string
*/
static function discover($url)
{
// @fixme ideally skip this for non-HTML stuff!
$body = self::http($url);
return self::discoverFromHTML($url, $body);
}
/**
* Partially ripped from OStatus' FeedDiscovery class.
*
* @param string $url source URL, used to resolve relative links
* @param string $body HTML body text
* @return mixed string with URL or false if no target found
*/
static function discoverFromHTML($url, $body)
{
// DOMDocument::loadHTML may throw warnings on unrecognized elements,
// and notices on unrecognized namespaces.
$old = error_reporting(error_reporting() & ~(E_WARNING | E_NOTICE));
$dom = new DOMDocument();
$ok = $dom->loadHTML($body);
error_reporting($old);
if (!$ok) {
throw new oEmbedHelper_BadHtmlException();
}
// Ok... now on to the links!
$feeds = array(
'application/json+oembed' => false,
);
$nodes = $dom->getElementsByTagName('link');
for ($i = 0; $i < $nodes->length; $i++) {
$node = $nodes->item($i);
if ($node->hasAttributes()) {
$rel = $node->attributes->getNamedItem('rel');
$type = $node->attributes->getNamedItem('type');
$href = $node->attributes->getNamedItem('href');
if ($rel && $type && $href) {
$rel = array_filter(explode(" ", $rel->value));
$type = trim($type->value);
$href = trim($href->value);
if (in_array('alternate', $rel) && array_key_exists($type, $feeds) && empty($feeds[$type])) {
// Save the first feed found of each type...
$feeds[$type] = $href;
}
}
}
}
// Return the highest-priority feed found
foreach ($feeds as $type => $url) {
if ($url) {
return $url;
}
}
throw new oEmbedHelper_DiscoveryException();
}
/**
* Actually do an oEmbed lookup to a particular API endpoint.
*
* @param string $api oEmbed API endpoint URL
* @param string $url target URL to look up info about
* @param array $params
* @return object
*/
static function getObjectFrom($api, $url, $params=array())
{
$params['url'] = $url;
$params['format'] = 'json';
$data = self::json($api, $params);
return self::normalize($data);
}
/**
* Normalize oEmbed format.
*
* @param object $orig
* @return object
*/
static function normalize($orig)
{
$data = clone($orig);
if (empty($data->type)) {
throw new Exception('Invalid oEmbed data: no type field.');
}
if ($data->type == 'image') {
// YFrog does this.
$data->type = 'photo';
}
if (isset($data->thumbnail_url)) {
if (!isset($data->thumbnail_width)) {
// !?!?!
$data->thumbnail_width = common_config('attachments', 'thumb_width');
$data->thumbnail_height = common_config('attachments', 'thumb_height');
}
}
return $data;
}
/**
* 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: ' . $response->getStatus());
}
}
}
class oEmbedHelper_Exception extends Exception
{
public function __construct($message = "", $code = 0, $previous = null)
{
parent::__construct($message, $code, $previous);
}
}
class oEmbedHelper_BadHtmlException extends oEmbedHelper_Exception
{
function __construct($previous=null)
{
return parent::__construct('Bad HTML in discovery data.', 0, $previous);
}
}
class oEmbedHelper_DiscoveryException extends oEmbedHelper_Exception
{
function __construct($previous=null)
{
return parent::__construct('No oEmbed discovery data.', 0, $previous);
}
}