Prototype support for amp-wordpress-embed component

includes/amp-helper-functions.php

@@ -810,6 +810,7 @@ function amp_get_content_embed_handlers( $post = null ) {
 			'AMP_Gfycat_Embed_Handler'      => [],
 			'AMP_Hulu_Embed_Handler'        => [],
 			'AMP_Imgur_Embed_Handler'       => [],
+			'AMP_WordPress_Embed_Handler'   => [],
 		],
 		$post
 	);

includes/class-amp-autoloader.php

@@ -59,6 +59,7 @@ class AMP_Autoloader {
 		'AMP_Twitter_Embed_Handler'          => 'includes/embeds/class-amp-twitter-embed',
 		'AMP_Vimeo_Embed_Handler'            => 'includes/embeds/class-amp-vimeo-embed',
 		'AMP_Vine_Embed_Handler'             => 'includes/embeds/class-amp-vine-embed',
+		'AMP_WordPress_Embed_Handler'        => 'includes/embeds/class-amp-wordpress-embed-handler',
 		'AMP_YouTube_Embed_Handler'          => 'includes/embeds/class-amp-youtube-embed',
 		'AMP_Analytics_Options_Submenu'      => 'includes/options/class-amp-analytics-options-submenu',
 		'AMP_Options_Menu'                   => 'includes/options/class-amp-options-menu',

includes/embeds/class-amp-wordpress-embed-handler.php

@@ -0,0 +1,94 @@
+<?php
+/**
+ * Class AMP_WordPress_Embed_Handler
+ *
+ * @package AMP
+ */
+
+/**
+ * Class AMP_WordPress_Embed_Handler
+ *
+ * @since 1.3.1
+ */
+class AMP_WordPress_Embed_Handler extends AMP_Base_Embed_Handler {
+
+	/**
+	 * Default height.
+	 *
+	 * Note that 200px is the minimum that WordPress allows for a post embed. This minimum height is enforced by
+	 * WordPress in the wp.receiveEmbedMessage() function, and the <amp-wordpress-embed> also enforces that same
+	 * minimum height. It is important for the minimum height to be initially used because if the actual post embed
+	 * window is _less_ than the initial, then no overflow button will be presented to resize the iframe to be
+	 * _smaller_. So this ensures that the iframe will only ever overflow to grow in height.
+	 *
+	 * @var int
+	 */
+	protected $DEFAULT_HEIGHT = 200;
+
+	/**
+	 * Register embed.
+	 */
+	public function register_embed() {
+		add_filter( 'embed_oembed_html', [ $this, 'filter_embed_oembed_html' ], 100, 2 );
+	}
+
+	/**
+	 * Unregister embed.
+	 */
+	public function unregister_embed() {
+		remove_filter( 'embed_oembed_html', [ $this, 'filter_embed_oembed_html' ], 100 );
+	}
+
+	/**
+	 * Filter oEmbed HTML for WordPress to convert to AMP.
+	 *
+	 * @param string $cache Cache for oEmbed.
+	 * @param string $url   Embed URL.
+	 * @return string Embed.
+	 */
+	public function filter_embed_oembed_html( $cache, $url ) {
+		/*
+		 * Example WordPress embed HTML that would be present in $cache.
+		 *
+		 * <blockquote class="wp-embedded-content" data-secret="xUuZHketRt">
+		 *     <a href="https://make.wordpress.org/core/2015/10/28/new-embeds-feature-in-wordpress-4-4/">New Embeds Feature in WordPress 4.4</a>
+		 * </blockquote>
+		 * <iframe
+		 *      title="&#8220;New Embeds Feature in WordPress 4.4&#8221; &#8212; Make WordPress Core"
+		 *      class="wp-embedded-content"
+		 *      sandbox="allow-scripts"
+		 *      security="restricted"
+		 *      style="position: absolute; clip: rect(1px, 1px, 1px, 1px);"
+		 *      src="https://make.wordpress.org/core/2015/10/28/new-embeds-feature-in-wordpress-4-4/embed/#?secret=xUuZHketRt"
+		 *      data-secret="xUuZHketRt"
+		 *      width="600"
+		 *      height="338"
+		 *      frameborder="0"
+		 *      marginwidth="0"
+		 *      marginheight="0"
+		 *      scrolling="no">
+		 * </iframe>
+		 */
+		if ( ! preg_match( '#<blockquote class="wp-embedded-content" data-secret="\w+">(.+?)</blockquote>#s', $cache, $matches ) ) {
+			return $cache;
+		}
+		$placeholder = sprintf( '<blockquote class="wp-embedded-content" placeholder>%s</blockquote>', $matches[1] );
+
+		$attributes = [
+			'height' => $this->args['height'],
+			'title'  => '',
+		];
+		if ( preg_match( '#<iframe[^>]*?title="(?P<title>[^"]+?)"#s', $cache, $matches ) ) {
+			$attributes['title'] = $matches['title'];
+		}
+
+		return sprintf(
+			'<amp-wordpress-embed layout="fixed-height" height="%d" title="%s" data-url="%s">%s<button overflow>%s</button></amp-wordpress-embed>',
+			esc_attr( $attributes['height'] ),
+			esc_attr( $attributes['title'] ),
+			esc_url( $url ),
+			$placeholder,
+			esc_html__( 'Expand', 'amp' )
+		);
+	}
+}

includes/sanitizers/class-amp-allowed-tags-generated.php

@@ -6395,6 +6395,31 @@ class AMP_Allowed_Tags_Generated {
 				),
 			),
 		),
+		'amp-wordpress-embed' => array(
+			array(
+				'attr_spec_list' => array(
+					'data-url' => array(
+						'mandatory' => true,
+						'value_url' => array(
+							'allow_relative' => false,
+							'protocol' => array(
+								'https',
+							),
+						),
+					),
+				),
+				'tag_spec' => array(
+					'amp_layout' => array(
+						'supported_layouts' => array(
+							3,
+						),
+					),
+					'requires_extension' => array(
+						'amp-wordpress-embed',
+					),
+				),
+			),
+		),
 		'amp-yotpo' => array(
 			array(
 				'attr_spec_list' => array(
@@ -14928,6 +14953,32 @@ class AMP_Allowed_Tags_Generated {
 					),
 				),
 			),
+			array(
+				'attr_spec_list' => array(
+					'async' => array(
+						'mandatory' => true,
+						'value' => array(
+							'',
+						),
+					),
+					'nonce' => array(),
+					'type' => array(
+						'value_casei' => array(
+							'text/javascript',
+						),
+					),
+				),
+				'tag_spec' => array(
+					'extension_spec' => array(
+						'name' => 'amp-wordpress-embed',
+						'version' => array(
+							'0.1',
+							'latest',
+						),
+					),
+					'spec_url' => 'https://amp.dev/documentation/components/amp-wordpress-embed',
+				),
+			),
 			array(
 				'attr_spec_list' => array(
 					'async' => array(