Porting MediaRSS from WordPress.com

README.md

@@ -26,6 +26,7 @@ The following custom WP-CLI commands exist in this plugin:
 ## Plugins
 
 * [Writing Helper](https://github.com/Automattic/writing-helper) - "Helps you write your posts."  This plugin is a feature on WordPress.com that allows posts to be copied and for feedback to be requested.  This plugin can be disabled by calling `add_filter( 'wpcom_compat_enable_writing_helper', '__return_false' );` before loading the WordPress.com Compatibility mu-plugin.
+* MediaRSS - This plugin adds compatibility for MediaRSS for RSS feeds, it's going to be merged in Jetpack at some point [Jetpack issue #11062](https://github.com/Automattic/jetpack/issues/11062), but for now it's a part of this compat plugin.
 
 ## Filters
 

plugins/mrss.php

@@ -0,0 +1,196 @@
+<?php
+/**
+ * This is not a verbatim copy of WP.com's version.
+ */
+if ( ! function_exists( 'mrss_init' ) ) {
+	add_action( 'template_redirect', 'mrss_init' );
+
+	function mrss_init() {
+		if ( ! is_feed() ) {
+			return;
+		}
+
+		if ( isset( $_GET['mrss'] ) && $_GET['mrss'] == 'off' ) {
+			return;
+		}
+
+		add_action( 'rss2_ns', 'mrss_ns' );
+		add_action( 'rss2_item', 'mrss_item', 10, 0 );
+	}
+
+	function mrss_ns() {
+		?>xmlns:media="http://search.yahoo.com/mrss/"
+		<?php
+	}
+
+	function mrss_item( $content = null ) {
+
+		global $shortcode_tags;
+
+		$meds            = array();
+		$_shortcode_tags = $shortcode_tags;
+		$shortcode_tags  = array( 'gallery' => 'gallery_shortcode' );
+
+		if ( ! isset( $content ) ) {
+			$content = get_the_content();
+		}
+
+		$content        = apply_filters( 'the_content_rss', $content );
+		$content        = do_shortcode( $content );
+		$shortcode_tags = $_shortcode_tags;
+
+		// img tags
+		if ( preg_match_all( '/<img (.+?)>/', $content, $matches ) ) {
+			foreach ( $matches[1] as $attrs ) {
+				$media = $img = array();
+				foreach ( wp_kses_hair( $attrs, array( 'http', 'https' ) ) as $attr ) {
+					$img[ $attr['name'] ] = $attr['value'];
+				}
+				if ( ! isset( $img['src'] ) || 0 !== strpos( $img['src'], 'http' ) ) {
+					continue;
+				}
+				$media['content']['attr']['url']    = esc_url( $img['src'] );
+				$media['content']['attr']['medium'] = 'image';
+				if ( ! empty( $img['title'] ) ) {
+					$media['content']['children']['title']['attr']['type'] = 'html';
+					$media['content']['children']['title']['children'][]   = $img['title'];
+				} elseif ( ! empty( $img['alt'] ) ) {
+					$media['content']['children']['title']['attr']['type'] = 'html';
+					$media['content']['children']['title']['children'][]   = $img['alt'];
+				}
+				$meds[] = $media;
+			}
+		}
+
+		// audio players
+		if ( preg_match_all( '!\[audio (.+)\]!i', $content, $matches ) ) {
+			foreach ( $matches[1] as $url ) {
+				$media = array();
+
+				// New-style media player puts the audio in a src or mp3 attribute.
+				// If we see an attribute starting with a https? url use that instead of the compat stuff below
+				if ( preg_match( '!\w+="(https?://[^"]+)"!', $url, $attribute_match ) ) {
+					$url = $attribute_match[1];
+				} else {
+					// Remove the audio player config args that start with the pipe symbol (&#124;)
+					$url = preg_replace( '/\&#124;.+/', '', $url );
+					$url = html_entity_decode( $url );
+					$url = preg_replace( '/[<>"\']/', '', $url );
+				}
+
+				$media['content']['attr']['url']    = esc_url( $url );
+				$media['content']['attr']['medium'] = 'audio';
+				$meds[]                             = $media;
+			}
+		}
+
+		$meds = apply_filters( 'mrss_media', $meds );
+
+		if ( ! empty( $meds ) ) {
+			foreach ( $meds as $media ) {
+				mrss_print( $media );
+			}
+		}
+	}
+
+	add_filter( 'mrss_media', 'mrss_featured_image' );
+
+	/* Add featured image, as first item */
+	function mrss_featured_image( $meds ) {
+
+		if ( ! ( function_exists( 'has_post_thumbnail' ) && has_post_thumbnail() ) ) {
+			return $meds;
+		}
+
+		$media = array();
+
+		$thumb_id  = get_post_thumbnail_id();
+		$thumb_url = wp_get_attachment_image_src( $thumb_id, 'full' );
+		$thumb_url = $thumb_url[0];
+
+		if ( ! empty( $thumb_url ) ) {
+			$media['thumbnail']['attr']['url']  = esc_url( $thumb_url );
+			$media['content']['attr']['url']    = esc_url( $thumb_url );
+			$media['content']['attr']['medium'] = 'image';
+		}
+
+		$thumbnail = & get_post( $thumb_id );
+		$title     = trim( strip_tags( $thumbnail->post_title ) );
+
+		if ( empty( $title ) ) {
+			$title = trim( strip_tags( get_post_meta( $thumb_id, '_wp_attachment_image_alt', true ) ) );
+		}
+
+		if ( ! empty( $title ) ) {
+			$media['content']['children']['title']['attr']['type'] = 'html';
+			$media['content']['children']['title']['children'][]   = $title;
+		}
+
+		// Remove from list if already there.
+		foreach ( $meds as $key => $med ) {
+			if ( $med['content']['attr']['url'] == $thumb_url ) {
+				unset( $meds[ $key ] );
+			}
+		}
+
+		// Add as first item
+		array_unshift( $meds, $media );
+
+		return $meds;
+	}
+
+	function mrss_news_item() {
+		foreach ( get_post_custom() as $k => $v ) {
+			if ( $k == $v[0] && strpos( $k, ':' ) ) {
+				list( $blog_id, $post_id ) = explode( ':', $k );
+				break;
+			}
+		}
+		$post = get_blog_post( $blog_id, $post_id );
+
+		mrss_item( $post->post_content );
+	}
+
+	function mrss_print( $element, $indent = 2 ) {
+
+		echo "\n";
+
+		foreach ( (array) $element as $name => $data ) {
+
+			echo str_repeat( "\t", $indent ) . "<media:$name";
+			if ( ! empty( $data['attr'] ) ) {
+				foreach ( $data['attr'] as $attr => $value ) {
+					echo " $attr=\"" . ent2ncr( esc_attr( $value ) ) . '"';
+				}
+			}
+			if ( ! empty( $data['children'] ) ) {
+				$nl = false;
+				echo '>';
+				foreach ( $data['children'] as $_name => $_data ) {
+
+					if ( is_int( $_name ) ) {
+
+						if ( ! is_array( $_data ) ) {
+							echo ent2ncr( esc_html( $_data ) );
+						} else {
+							// allow nested same level elements
+							$nl = true;
+							mrss_print( $_data, $indent + 1 );
+						}
+					} else {
+						$nl = true;
+						mrss_print( array( $_name => $_data ), $indent + 1 );
+					}
+				}
+
+				if ( $nl ) {
+					echo str_repeat( "\t", $indent );
+				}
+
+				echo "</media:$name>\n";
+			} else {
+				echo " />\n";
+			}
+		}
+	}
+}

wpcom-plugins.php

@@ -26,3 +26,5 @@ function wpcom_vip_legacy_load_plugin( $plugin = false, $folder = false, $versio
 if ( true === apply_filters( 'wpcom_compat_enable_writing_helper', true ) && ! class_exists( 'Writing_Helper' ) ) {
 	require __DIR__ . '/plugins/writing-helper/writing-helper.php';
 }
+
+require_once __DIR__ . '/plugins/mrss.php';