<?php

/**

 * API for easily embedding rich media such as videos and images into content.

 *

 * @package WordPress

 * @subpackage Embed

 * @since 2.9.0

 */

class WP_Embed {

	var $handlers = array();

	var $post_ID;

	var $usecache = true;

	var $linkifunknown = true;

	/**

	 * Constructor

	 */

	function __construct() {

		// Hack to get the [embed] shortcode to run before wpautop()

		add_filter( 'the_content', array( $this, 'run_shortcode' ), 8 );

		// Shortcode placeholder for strip_shortcodes()

		add_shortcode( 'embed', '__return_false' );

		// Attempts to embed all URLs in a post

		add_filter( 'the_content', array( $this, 'autoembed' ), 8 );

		// When a post is saved, invalidate the oEmbed cache

		add_action( 'pre_post_update', array( $this, 'delete_oembed_caches' ) );

		// After a post is saved, cache oEmbed items via AJAX

		add_action( 'edit_form_advanced', array( $this, 'maybe_run_ajax_cache' ) );

	}

	/**

	 * Process the [embed] shortcode.

	 *

	 * Since the [embed] shortcode needs to be run earlier than other shortcodes,

	 * this function removes all existing shortcodes, registers the [embed] shortcode,

	 * calls {@link do_shortcode()}, and then re-registers the old shortcodes.

	 *

	 * @uses $shortcode_tags

	 * @uses remove_all_shortcodes()

	 * @uses add_shortcode()

	 * @uses do_shortcode()

	 *

	 * @param string $content Content to parse

	 * @return string Content with shortcode parsed

	 */

	function run_shortcode( $content ) {

		global $shortcode_tags;

		// Back up current registered shortcodes and clear them all out

		$orig_shortcode_tags = $shortcode_tags;

		remove_all_shortcodes();

		add_shortcode( 'embed', array( $this, 'shortcode' ) );

		// Do the shortcode (only the [embed] one is registered)

		$content = do_shortcode( $content );

		// Put the original shortcodes back

		$shortcode_tags = $orig_shortcode_tags;

		return $content;

	}

	/**

	 * If a post/page was saved, then output JavaScript to make

	 * an AJAX request that will call WP_Embed::cache_oembed().

	 */

	function maybe_run_ajax_cache() {

		$post = get_post();

		if ( ! $post || empty($_GET['message']) || 1 != $_GET['message'] )

			return;

?>

<script type="text/javascript">

/* <![CDATA[ */

	jQuery(document).ready(function($){

		$.get("<?php echo admin_url( 'admin-ajax.php?action=oembed-cache&post=' . $post->ID, 'relative' ); ?>");

	});

/* ]]> */

</script>

<?php

	}

	/**

	 * Register an embed handler. Do not use this function directly, use {@link wp_embed_register_handler()} instead.

	 * This function should probably also only be used for sites that do not support oEmbed.

	 *

	 * @param string $id An internal ID/name for the handler. Needs to be unique.

	 * @param string $regex The regex that will be used to see if this handler should be used for a URL.

	 * @param callback $callback The callback function that will be called if the regex is matched.

	 * @param int $priority Optional. Used to specify the order in which the registered handlers will be tested (default: 10). Lower numbers correspond with earlier testing, and handlers with the same priority are tested in the order in which they were added to the action.

	 */

	function register_handler( $id, $regex, $callback, $priority = 10 ) {

		$this->handlers[$priority][$id] = array(

			'regex'    => $regex,

			'callback' => $callback,

		);

	}

	/**

	 * Unregister a previously registered embed handler. Do not use this function directly, use {@link wp_embed_unregister_handler()} instead.

	 *

	 * @param string $id The handler ID that should be removed.

	 * @param int $priority Optional. The priority of the handler to be removed (default: 10).

	 */

	function unregister_handler( $id, $priority = 10 ) {

		if ( isset($this->handlers[$priority][$id]) )

			unset($this->handlers[$priority][$id]);

	}

	/**

	 * The {@link do_shortcode()} callback function.

	 *

	 * Attempts to convert a URL into embed HTML. Starts by checking the URL against the regex of the registered embed handlers.

	 * If none of the regex matches and it's enabled, then the URL will be given to the {@link WP_oEmbed} class.

	 *

	 * @uses wp_oembed_get()

	 * @uses wp_parse_args()

	 * @uses wp_embed_defaults()

	 * @uses WP_Embed::maybe_make_link()

	 * @uses get_option()

	 * @uses author_can()

	 * @uses wp_cache_get()

	 * @uses wp_cache_set()

	 * @uses get_post_meta()

	 * @uses update_post_meta()

	 *

	 * @param array $attr Shortcode attributes.

	 * @param string $url The URL attempting to be embedded.

	 * @return string The embed HTML on success, otherwise the original URL.

	 */

	function shortcode( $attr, $url = '' ) {

		$post = get_post();

		if ( empty( $url ) )

			return '';

		$rawattr = $attr;

		$attr = wp_parse_args( $attr, wp_embed_defaults() );

		// kses converts & into & and we need to undo this

		// See http://core.trac.wordpress.org/ticket/11311

		$url = str_replace( '&', '&', $url );

		// Look for known internal handlers

		ksort( $this->handlers );

		foreach ( $this->handlers as $priority => $handlers ) {

			foreach ( $handlers as $id => $handler ) {

				if ( preg_match( $handler['regex'], $url, $matches ) && is_callable( $handler['callback'] ) ) {

					if ( false !== $return = call_user_func( $handler['callback'], $matches, $attr, $url, $rawattr ) )

						/**

						 * Filter the returned embed handler.

						 *

						 * @since 2.9.0

						 *

						 * @param mixed  $return The shortcode callback function to call.

						 * @param string $url    The attempted embed URL.

						 * @param array  $attr   An array of shortcode attributes.

						 */

						return apply_filters( 'embed_handler_html', $return, $url, $attr );

				}

			}

		}

		$post_ID = ( ! empty( $post->ID ) ) ? $post->ID : null;

		if ( ! empty( $this->post_ID ) ) // Potentially set by WP_Embed::cache_oembed()

			$post_ID = $this->post_ID;

		// Unknown URL format. Let oEmbed have a go.

		if ( $post_ID ) {

			// Check for a cached result (stored in the post meta)

			$cachekey = '_oembed_' . md5( $url . serialize( $attr ) );

			if ( $this->usecache ) {

				$cache = get_post_meta( $post_ID, $cachekey, true );

				// Failures are cached

				if ( '{{unknown}}' === $cache )

					return $this->maybe_make_link( $url );

				if ( ! empty( $cache ) )

					/**

					 * Filter the cached oEmbed HTML.

					 *

					 * @since 2.9.0

					 *

					 * @param mixed  $cache   The cached HTML result, stored in post meta.

					 * @param string $url     The attempted embed URL.

					 * @param array  $attr    An array of shortcode attributes.

					 * @param int    $post_ID Post ID.

					 */

					return apply_filters( 'embed_oembed_html', $cache, $url, $attr, $post_ID );

			}

			/**

			 * Filter whether to inspect the given URL for discoverable <link> tags.

			 *

			 * @see WP_oEmbed::discover()

			 *

			 * @param bool false Whether to enable <link> tag discovery. Default false.

			 */

			$attr['discover'] = ( apply_filters( 'embed_oembed_discover', false ) && author_can( $post_ID, 'unfiltered_html' ) );

			// Use oEmbed to get the HTML

			$html = wp_oembed_get( $url, $attr );

			// Cache the result

			$cache = ( $html ) ? $html : '{{unknown}}';

			update_post_meta( $post_ID, $cachekey, $cache );

			// If there was a result, return it

			if ( $html ) {

				/** This filter is documented in wp-includes/class-wp-embed.php */

				return apply_filters( 'embed_oembed_html', $html, $url, $attr, $post_ID );

			}

		}

		// Still unknown

		return $this->maybe_make_link( $url );

	}

	/**

	 * Delete all oEmbed caches.

	 *

	 * @param int $post_ID Post ID to delete the caches for.

	 */

	function delete_oembed_caches( $post_ID ) {

		$post_metas = get_post_custom_keys( $post_ID );

		if ( empty($post_metas) )

			return;

		foreach( $post_metas as $post_meta_key ) {

			if ( '_oembed_' == substr( $post_meta_key, 0, 8 ) )

				delete_post_meta( $post_ID, $post_meta_key );

		}

	}

	/**

	 * Triggers a caching of all oEmbed results.

	 *

	 * @param int $post_ID Post ID to do the caching for.

	 */

	function cache_oembed( $post_ID ) {

		$post = get_post( $post_ID );

		$post_types = array( 'post', 'page' );

		/**

		 * Filter the array of post types to cache oEmbed results for.

		 *

		 * @since 2.9.0

		 *

		 * @param array $post_types Array of post types to cache oEmbed results for. Default 'post', 'page'.

		 */

		if ( empty($post->ID) || !in_array( $post->post_type, apply_filters( 'embed_cache_oembed_types', $post_types ) ) )

			return;

		// Trigger a caching

		if ( !empty($post->post_content) ) {

			$this->post_ID = $post->ID;

			$this->usecache = false;

			$content = $this->run_shortcode( $post->post_content );

			$this->autoembed( $content );

			$this->usecache = true;

		}

	}

	/**

	 * Passes any unlinked URLs that are on their own line to {@link WP_Embed::shortcode()} for potential embedding.

	 *

	 * @uses WP_Embed::autoembed_callback()

	 *

	 * @param string $content The content to be searched.

	 * @return string Potentially modified $content.

	 */

	function autoembed( $content ) {

		return preg_replace_callback( '|^\s*(https?://[^\s"]+)\s*$|im', array( $this, 'autoembed_callback' ), $content );

	}

	/**

	 * Callback function for {@link WP_Embed::autoembed()}.

	 *

	 * @uses WP_Embed::shortcode()

	 *

	 * @param array $match A regex match array.

	 * @return string The embed HTML on success, otherwise the original URL.

	 */

	function autoembed_callback( $match ) {

		$oldval = $this->linkifunknown;

		$this->linkifunknown = false;

		$return = $this->shortcode( array(), $match[1] );

		$this->linkifunknown = $oldval;

		return "\n$return\n";

	}

	/**

	 * Conditionally makes a hyperlink based on an internal class variable.

	 *

	 * @param string $url URL to potentially be linked.

	 * @return string Linked URL or the original URL.

	 */

	function maybe_make_link( $url ) {

		$output = ( $this->linkifunknown ) ? '<a href="' . esc_url($url) . '">' . esc_html($url) . '</a>' : $url;

		/**

		 * Filter the returned, maybe-linked embed URL.

		 *

		 * @since 2.9.0

		 *

		 * @param string $output The linked or original URL.

		 * @param string $url    The original URL.

		 */

		return apply_filters( 'embed_maybe_make_link', $output, $url );

	}

}

$GLOBALS['wp_embed'] = new WP_Embed();