Wordpress oEmbed Class

<?php
/**
 * API for fetching the HTML to embed remote content based on a provided URL.
 * Used internally by the {@link WP_Embed} class, but is designed to be generic.
 *
 * @link http://codex.wordpress.org/oEmbed oEmbed Codex Article
 * @link http://oembed.com/ oEmbed Homepage
 *
 * @package WordPress
 * @subpackage oEmbed
 */

/**
 * oEmbed class.
 *
 * @package WordPress
 * @subpackage oEmbed
 * @since 2.9.0
 */
class WP_oEmbed {
    var $providers = array();

    /**
     * Constructor
     *
     * @uses apply_filters() Filters a list of pre-defined oEmbed providers.
     */
    function __construct() {
        // List out some popular sites that support oEmbed.
        // The WP_Embed class disables discovery for non-unfiltered_html users, so only providers in this array will be used for them.
        // Add to this list using the wp_oembed_add_provider() function (see its PHPDoc for details).
        $this->providers = apply_filters( 'oembed_providers', array(
            '#http://(www\.)?youtube.com/watch.*#i'         => array( 'http://www.youtube.com/oembed',            true  ),
            'http://youtu.be/*'                             => array( 'http://www.youtube.com/oembed',            false ),
            'http://blip.tv/*'                              => array( 'http://blip.tv/oembed/',                   false ),
            '#http://(www\.)?vimeo\.com/.*#i'               => array( 'http://vimeo.com/api/oembed.{format}',     true  ),
            '#http://(www\.)?dailymotion\.com/.*#i'         => array( 'http://www.dailymotion.com/api/oembed',    true  ),
            '#http://(www\.)?flickr\.com/.*#i'              => array( 'http://www.flickr.com/services/oembed/',   true  ),
            '#http://(.+\.)?smugmug\.com/.*#i'              => array( 'http://api.smugmug.com/services/oembed/',  true  ),
            '#http://(www\.)?hulu\.com/watch/.*#i'          => array( 'http://www.hulu.com/api/oembed.{format}',  true  ),
            '#http://(www\.)?viddler\.com/.*#i'             => array( 'http://lab.viddler.com/services/oembed/',  true  ),
            'http://qik.com/*'                              => array( 'http://qik.com/api/oembed.{format}',       false ),
            'http://revision3.com/*'                        => array( 'http://revision3.com/api/oembed/',         false ),
            'http://i*.photobucket.com/albums/*'            => array( 'http://photobucket.com/oembed',            false ),
            'http://gi*.photobucket.com/groups/*'           => array( 'http://photobucket.com/oembed',            false ),
            '#http://(www\.)?scribd\.com/.*#i'              => array( 'http://www.scribd.com/services/oembed',    true  ),
            'http://wordpress.tv/*'                         => array( 'http://wordpress.tv/oembed/',              false ),
            '#http://(.+\.)?polldaddy\.com/.*#i'            => array( 'http://polldaddy.com/oembed/',             true  ),
            '#http://(www\.)?funnyordie\.com/videos/.*#i'   => array( 'http://www.funnyordie.com/oembed',         true  ),
        ) );

        // Fix any embeds that contain new lines in the middle of the HTML which breaks wpautop().
        add_filter( 'oembed_dataparse', array(&$this, '_strip_newlines'), 10, 3 );
    }

    /**
     * The do-it-all function that takes a URL and attempts to return the HTML.
     *
     * @see WP_oEmbed::discover()
     * @see WP_oEmbed::fetch()
     * @see WP_oEmbed::data2html()
     *
     * @param string $url The URL to the content that should be attempted to be embedded.
     * @param array $args Optional arguments. Usually passed from a shortcode.
     * @return bool|string False on failure, otherwise the UNSANITIZED (and potentially unsafe) HTML that should be used to embed.
     */
    function get_html( $url, $args = '' ) {
        $provider = false;

        if ( !isset($args['discover']) )
            $args['discover'] = true;

        foreach ( $this->providers as $matchmask => $data ) {
            list( $providerurl, $regex ) = $data;

            // Turn the asterisk-type provider URLs into regex
            if ( !$regex )
                $matchmask = '#' . str_replace( '___wildcard___', '(.+)', preg_quote( str_replace( '*', '___wildcard___', $matchmask ), '#' ) ) . '#i';

            if ( preg_match( $matchmask, $url ) ) {
                $provider = str_replace( '{format}', 'json', $providerurl ); // JSON is easier to deal with than XML
                break;
            }
        }

        if ( !$provider && $args['discover'] )
            $provider = $this->discover( $url );

        if ( !$provider || false === $data = $this->fetch( $provider, $url, $args ) )
            return false;

        return apply_filters( 'oembed_result', $this->data2html( $data, $url ), $url, $args );
    }

    /**
     * Attempts to find oEmbed provider discovery <link> tags at the given URL.
     *
     * @param string $url The URL that should be inspected for discovery <link> tags.
     * @return bool|string False on failure, otherwise the oEmbed provider URL.
     */
    function discover( $url ) {
        $providers = array();

        // Fetch URL content
        if ( $html = wp_remote_retrieve_body( wp_remote_get( $url ) ) ) {

            // <link> types that contain oEmbed provider URLs
            $linktypes = apply_filters( 'oembed_linktypes', array(
                'application/json+oembed' => 'json',
                'text/xml+oembed' => 'xml',
                'application/xml+oembed' => 'xml', // Incorrect, but used by at least Vimeo
            ) );

            // Strip <body>
            $html = substr( $html, 0, stripos( $html, '</head>' ) );

            // Do a quick check
            $tagfound = false;
            foreach ( $linktypes as $linktype => $format ) {
                if ( stripos($html, $linktype) ) {
                    $tagfound = true;
                    break;
                }
            }

            if ( $tagfound && preg_match_all( '/<link([^<>]+)>/i', $html, $links ) ) {
                foreach ( $links[1] as $link ) {
                    $atts = shortcode_parse_atts( $link );

                    if ( !empty($atts['type']) && !empty($linktypes[$atts['type']]) && !empty($atts['href']) ) {
                        $providers[$linktypes[$atts['type']]] = $atts['href'];

                        // Stop here if it's JSON (that's all we need)
                        if ( 'json' == $linktypes[$atts['type']] )
                            break;
                    }
                }
            }
        }

        // JSON is preferred to XML
        if ( !empty($providers['json']) )
            return $providers['json'];
        elseif ( !empty($providers['xml']) )
            return $providers['xml'];
        else
            return false;
    }

    /**
     * Connects to a oEmbed provider and returns the result.
     *
     * @param string $provider The URL to the oEmbed provider.
     * @param string $url The URL to the content that is desired to be embedded.
     * @param array $args Optional arguments. Usually passed from a shortcode.
     * @return bool|object False on failure, otherwise the result in the form of an object.
     */
    function fetch( $provider, $url, $args = '' ) {
        $args = wp_parse_args( $args, wp_embed_defaults() );

        $provider = add_query_arg( 'maxwidth', (int) $args['width'], $provider );
        $provider = add_query_arg( 'maxheight', (int) $args['height'], $provider );
        $provider = add_query_arg( 'url', urlencode($url), $provider );

        foreach( array( 'json', 'xml' ) as $format ) {
            $result = $this->_fetch_with_format( $provider, $format );
            if ( is_wp_error( $result ) && 'not-implemented' == $result->get_error_code() )
                continue;
            return ( $result && ! is_wp_error( $result ) ) ? $result : false;
        }
        return false;
    }

    /**
     * Fetches result from an oEmbed provider for a specific format and complete provider URL
     *
     * @since 3.0.0
     * @access private
     * @param string $provider_url_with_args URL to the provider with full arguments list (url, maxheight, etc.)
     * @param string $format Format to use
     * @return bool|object False on failure, otherwise the result in the form of an object.
     */
    function _fetch_with_format( $provider_url_with_args, $format ) {
        $provider_url_with_args = add_query_arg( 'format', $format, $provider_url_with_args );
        $response = wp_remote_get( $provider_url_with_args );
        if ( 501 == wp_remote_retrieve_response_code( $response ) )
            return new WP_Error( 'not-implemented' );
        if ( ! $body = wp_remote_retrieve_body( $response ) )
            return false;
        $parse_method = "_parse_$format";
        return $this->$parse_method( $body );
    }

    /**
     * Parses a json response body.
     *
     * @since 3.0.0
     * @access private
     */
    function _parse_json( $response_body ) {
        return ( ( $data = json_decode( trim( $response_body ) ) ) && is_object( $data ) ) ? $data : false;
    }

    /**
     * Parses an XML response body.
     *
     * @since 3.0.0
     * @access private
     */
    function _parse_xml( $response_body ) {
        if ( function_exists('simplexml_load_string') ) {
            $errors = libxml_use_internal_errors( 'true' );
            $data = simplexml_load_string( $response_body );
            libxml_use_internal_errors( $errors );
            if ( is_object( $data ) )
                return $data;
        }
        return false;
    }

    /**
     * Converts a data object from {@link WP_oEmbed::fetch()} and returns the HTML.
     *
     * @param object $data A data object result from an oEmbed provider.
     * @param string $url The URL to the content that is desired to be embedded.
     * @return bool|string False on error, otherwise the HTML needed to embed.
     */
    function data2html( $data, $url ) {
        if ( !is_object($data) || empty($data->type) )
            return false;

        switch ( $data->type ) {
            case 'photo':
                if ( empty($data->url) || empty($data->width) || empty($data->height) )
                    return false;

                $title = ( !empty($data->title) ) ? $data->title : '';
                $return = '<a href="' . esc_url( $url ) . '"><img src="' . esc_url( $data->url ) . '" alt="' . esc_attr($title) . '" width="' . esc_attr($data->width) . '" height="' . esc_attr($data->height) . '" /></a>';
                break;

            case 'video':
            case 'rich':
                $return = ( !empty($data->html) ) ? $data->html : false;
                break;

            case 'link':
                $return = ( !empty($data->title) ) ? '<a href="' . esc_url($url) . '">' . esc_html($data->title) . '</a>' : false;
                break;

            default;
                $return = false;
        }

        // You can use this filter to add support for custom data types or to filter the result
        return apply_filters( 'oembed_dataparse', $return, $data, $url );
    }

    /**
     * Strip any new lines from the HTML.
     *
     * @access private
     * @param string $html Existing HTML.
     * @param object $data Data object from WP_oEmbed::data2html()
     * @param string $url The original URL passed to oEmbed.
     * @return string Possibly modified $html
     */
    function _strip_newlines( $html, $data, $url ) {
        if ( false !== strpos( $html, "\n" ) )
            $html = str_replace( array( "\r\n", "\n" ), '', $html );

        return $html;
    }
}

/**
 * Returns the initialized {@link WP_oEmbed} object
 *
 * @since 2.9.0
 * @access private
 *
 * @see WP_oEmbed
 * @uses WP_oEmbed
 *
 * @return WP_oEmbed object.
 */
function &_wp_oembed_get_object() {
    static $wp_oembed;

    if ( is_null($wp_oembed) )
        $wp_oembed = new WP_oEmbed();

    return $wp_oembed;
}

?>