Media grabber class in development.

hybrid-media-grabber.php

<?php
/**
 * Hybrid Media Grabber - A script for grabbing media related to a post.
 *
 * Hybrid Media Grabber is a script for pulling media either from the post content or attached to the 
 * post.  It's an attempt to consolidate the various methods that users have used over the years to 
 * embed media into their posts.  This script was written so that theme developers could grab that 
 * media and use it in interesting ways within their themes.  For example, a theme could get a video 
 * and display it on archive pages alongside the post excerpt.
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU 
 * General Public License as published by the Free Software Foundation; either version 2 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.
 *
 * @package   HybridMediaGrabber
 * @version   0.1.0 - Alpha
 * @author    Justin Tadlock <justin@justintadlock.com>
 * @copyright Copyright (c) 2013, Justin Tadlock
 * @link      http://themehybrid.com
 * @license   http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 */

/**
 * Wrapper function for the Hybrid_Media_Grabber class.  Returns the HTML output for the found media.
 *
 * @since  0.1.0
 * @access public
 * @param  array
 * @return string
 */
function hybrid_media_grabber( $args = array() ) {

	$media = new Hybrid_Media_Grabber( $args );

	return $media->get_media();
}

/**
 * Grabs media related to the post.
 *
 * @since  0.1.0
 * @access public
 * @return void
 */
class Hybrid_Media_Grabber {

	/**
	 * The HTML version of the media to return.
	 *
	 * @since  0.1.0
	 * @access public
	 * @var    string
	 */
	public $media = '';

	/**
	 * The type of media to get.  Current supported types are 'audio' and 'video'.
	 *
	 * @since  0.1.0
	 * @access public
	 * @var    string
	 */
	public $type = 'video';

	/**
	 * Arguments passed into the class and parsed with the defaults.
	 *
	 * @since  0.1.0
	 * @access public
	 * @var    array
	 */
	public $args = array();

	/**
	 * The content to search for embedded media within.
	 *
	 * @since  0.1.0
	 * @access public
	 * @var    string
	 */
	public $content = '';

	/**
	 * Constructor method.  Sets up the media grabber.
	 *
	 * @since  0.1.0
	 * @access public
	 * @global object $wp_embed
	 * @return void
	 */
	public function __construct( $args = array() ) {
		global $wp_embed;

		add_filter( 'hybrid_media_grabber_embed_shortcode_media', array( $wp_embed, 'run_shortcode' ) );
		add_filter( 'hybrid_media_grabber_get_auto_embed',        array( $wp_embed, 'autoembed' ) );
		add_filter( 'embed_maybe_make_link',                      '__return_false' );

		$defaults = array(
			'type'   => 'video',
			'width'  => 0,
			'height' => 0,
			'before' => '',
			'after'  => ''
		);

		$this->args    = wp_parse_args( $args, $defaults );
		$this->content = get_the_content();
		$this->type    = isset( $this->args['type'] ) && in_array( $this->args['type'], array( 'audio', 'video' ) ) ? $this->args['type'] : 'video';
	}

	/**
	 * Destructor method.  Removes filters we needed to add.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function __destruct() {

		remove_filter( 'embed_maybe_make_link', '__return_false' );
	}

	/**
	 * Tries several methods to find media related to the post.  Returns the found media.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return string
	 */
	public function get_media() {

		/* Find media in the post content based on WordPress' media-related shortcodes. */
		$this->do_shortcode_embed();

		/* If no media is found and autoembeds are enabled, check for autoembeds. */
		if ( empty( $this->media ) && get_option( 'embed_autourls' ) )
			$this->do_auto_embed();

		/* If no media is found, check for media HTML within the post content. */
		if ( empty( $this->media ) )
			$this->do_embedded_media();

		/* If no media is found, check for media attached to the post. */
		if ( empty( $this->media ) )
			$this->do_attached_media();

		/* If media is found, add any HTML before and after it if set in the arguments. */
		if ( !empty( $media ) ) {

			if ( isset( $this->args['before'] ) )
				$this->media = $this->args['before'] . $this->media;

			if ( isset( $this->args['after'] ) )
				$this->media .= $this->args['after'];
		}

		/* Return the media. */
		return $this->filter_dimensions( $this->media );
	}

	/**
	 * WordPress has a few shortcodes for handling embedding media:  [audio], [video], and [embed].  This 
	 * method figures out the shortcode used in the content.  Once it's found, the appropriate method for 
	 * the shortcode is executed.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function do_shortcode_embed() {

		/* Finds matches for shortcodes in the content. */
		preg_match_all( '/' . get_shortcode_regex() . '/s', $this->content, $matches, PREG_SET_ORDER );

		/* If matches are found, loop through them and check if they match one of WP's media shortcodes. */
		if ( !empty( $matches ) ) {

			foreach ( $matches as $shortcode ) {

				/* Call the method related to the specific shortcode found and break out of the loop. */
				if ( in_array( $shortcode[2], array( 'embed', 'audio', 'video' ) ) ) {
					call_user_func( array( $this, "{$shortcode[2]}_shortcode_media" ), $shortcode );
					break;
				}
			}
		}
	}

	/**
	 * Handles the HTML when the [embed] shortcode is used.
	 *
	 * @since  0.1.0
	 * @access public
	 * @param  array  $shortcode
	 * @return void
	 */
	public function embed_shortcode_media( $shortcode ) {

		$this->media = apply_filters(
			'hybrid_media_grabber_embed_shortcode_media',
			array_shift( $shortcode )
		);
	}

	/**
	 * Handles the HTML when the [audio] shortcode is used.
	 *
	 * @since  0.1.0
	 * @access public
	 * @param  array  $shortcode
	 * @return void
	 */
	public function audio_shortcode_media( $shortcode ) {

		$this->media = do_shortcode( array_shift( $shortcode ) );
	}

	/**
	 * Handles the HTML when the [video] shortcode is used.
	 *
	 * @since  0.1.0
	 * @access public
	 * @param  array  $shortcode
	 * @return void
	 */
	public function video_shortcode_media( $shortcode ) {

		$this->media = do_shortcode( array_shift( $shortcode ) );
	}

	/**
	 * Uses WordPress' autoembed feature to automatically to handle media that's just input as a URL.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function do_auto_embed() {

		preg_match_all( '|^\s*(https?://[^\s"]+)\s*$|im', $this->content, $matches, PREG_SET_ORDER );

		/* If URL matches are found, loop through them to see if we can get an embed. */
		if ( is_array( $matches ) ) {

			foreach ( $matches as $value ) {

				/* Let WP work its magic with the 'autoembed' method. */
				$embed = apply_filters( 'hybrid_media_grabber_get_auto_embed', $value[0] );

				if ( !empty( $embed ) ) {
					$this->media = $embed;
					break;
				}
			}
		}
	}

	/**
	 * Grabs media embbeded into the content within <iframe>, <object>, <embed>, and other HTML methods for 
	 * embedding media.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function do_embedded_media() {

		$embedded_media = get_media_embedded_in_content( $this->content );

		if ( !empty( $embedded_media ) )
			$this->media = array_shift( $embedded_media );
	}

	/**
	 * Gets media attached to the post.  Then, uses the WordPress [audio] or [video] shortcode to handle 
	 * the HTML output of the media.
	 *
	 * @since  0.1.0
	 * @access public
	 * @return void
	 */
	public function do_attached_media() {

		/* Gets media attached to the post by mime type. */
		$attached_media = get_attached_media( $this->type );

		/* If media is found. */
		if ( !empty( $attached_media ) ) {

			/* Get the first attachment/post object found for the post. */
			$post = array_shift( $attached_media );

			/* Gets the URI for the attachment (the media file). */
			$url = wp_get_attachment_url( $post->ID );

			/* Run the media as a shortcode using WordPress' built-in [audio] and [video] shortcodes. */
			$this->media = do_shortcode( "[{$this->type} src='{$url}']" );
		}
	}

	/**
	 * Method for filtering the media's 'width' and 'height' attributes so that the theme can handle the 
	 * dimensions how it sees fit.
	 *
	 * @since  0.1.0
	 * @access public
	 * @param  string  $html
	 * @return string
	 */
	public function filter_dimensions( $html ) {

		$patterns     = array();
		$replacements = array();

		if ( !empty( $this->args['width'] ) ) {
			$patterns[]     = '/(width=[\'"]).+?([\'"])/i';
			$replacements[] = '${1}' . $this->args['width'] . '${2}';
		}

		if ( !empty( $this->args['height'] ) ) {
			$patterns[]     = '/(height=[\'"]).+?([\'"])/i';
			$replacements[] = '${1}' . $this->args['height'] . '${2}';
		}

		if ( !empty( $patterns ) && !empty( $replacements ) )
			return preg_replace( $patterns, $replacements, $html );

		return $html;
	}
}

?>

Ignore my last comment. I guess it doesn't belong here.