Add support for allowing a site subset to be native AMP

amp.php

@@ -272,28 +272,55 @@ function amp_correct_query_when_is_front_page( WP_Query $query ) {
 }
 
 /**
- * Whether this is in 'canonical mode.'
+ * Whether this is in 'canonical mode'.
  *
- * Themes can register support for this with `add_theme_support( 'amp' )`.
- * Then, this will change the plugin from 'paired mode,' and it won't use its own templates.
- * Nor output frontend markup like the 'rel' link. If the theme registers support for AMP with:
- * `add_theme_support( 'amp', array( 'template_dir' => 'my-amp-templates' ) )`
- * it will retain 'paired mode.
+ * Themes can register support for this with `add_theme_support( 'amp' )`:
  *
- * @return boolean Whether this is in AMP 'canonical mode'.
+ *      add_theme_support( 'amp' );
+ *
+ * This will serve templates in native AMP by default but the user would be able to change the template mode
+ * from native to paired in the admin. To force only native to be available, such as when you are using AMP components
+ * in your theme templates, do:
+ *
+ *      add_theme_support( 'amp', array(
+ *          'mode' => 'native',
+ *      ) );
+ *
+ * If you want to force AMP to always be served on a given template, use the amp_supportable_templates filter,
+ * for example to always serve the Category template in AMP:
+ *
+ *      add_filter( 'amp_supportable_templates', function( $templates ) {
+ *          $templates['is_category']['supported'] = true;
+ *          return $template;
+ *      } );
+ *
+ * Or if you want to prevent AMP from ever being served on the homepage:
+ *
+ *      add_filter( 'amp_supportable_templates', function( $templates ) {
+ *          $templates['is_front_page']['supported'] = false;
+ *          return $template;
+ *      } );
+ *
+ * @todo There needs to be a required flag which is the same as forcing all to be supported. This would be the same in the UI as the all_templates_supported flag. Might as well rename all_templates_supported to just required. If required is set to be false, or if any of the supported templates are immutable, then this option should not be available.
+ *
+ * @return boolean Whether this is in AMP 'canonical' mode, that is whether it is native and there is not separate AMP URL current URL.
  */
 function amp_is_canonical() {
-	$support = get_theme_support( 'amp' );
-	if ( true === $support ) {
-		return true;
+	if ( ! current_theme_supports( 'amp' ) ) {
+		return false;
 	}
+
+	$mode    = 'native';
+	$support = get_theme_support( 'amp' );
 	if ( is_array( $support ) ) {
 		$args = array_shift( $support );
-		if ( empty( $args['template_dir'] ) ) {
-			return true;
+		if ( isset( $args['mode'] ) ) {
+			$mode = $args['mode'];
+		} elseif ( ! empty( $args['template_dir'] ) ) {
+			$mode = 'paired'; // If there is a template_dir, then paired mode is implied.
 		}
 	}
-	return false;
+	return 'native' === $mode;
 }
 
 /**
@@ -426,6 +453,7 @@ function _amp_bootstrap_customizer() {
 
 /**
  * Redirects the old AMP URL to the new AMP URL.
+ *
  * If post slug is updated the amp page with old post slug will be redirected to the updated url.
  *
  * @since 0.5

includes/admin/class-amp-post-meta-box.php

@@ -170,16 +170,38 @@ public function render_status( $post ) {
 			is_post_type_viewable( $post->post_type )
 			&&
 			current_user_can( 'edit_post', $post->ID )
-			&&
-			! amp_is_canonical()
+			// @todo What if a site does not have non-AMP pages? Formerly this was indicated via amp_is_canonical(). Now we need a flag for whether AMP is exclusive to a theme, in which case all templates and post types must render AMP. In other words, all_templates_supported.
 		);
 
 		if ( true !== $verify ) {
 			return;
 		}
 
 		$errors = AMP_Post_Type_Support::get_support_errors( $post );
-		$status = post_supports_amp( $post ) ? self::ENABLED_STATUS : self::DISABLED_STATUS;
+		$status = empty( $errors ) ? self::ENABLED_STATUS : self::DISABLED_STATUS;
+		$errors = array_diff( $errors, array( 'post-status-disabled' ) ); // Subtract the status which the metabox will allow to be toggled.
+
+		// @todo If ! supported and immutable, don't show the toggle at all?
+		// Handle special case of the static front page or page for posts.
+		if ( current_theme_supports( 'amp' ) ) {
+
+			$query = new WP_Query();
+			if ( 'page' === $post->post_type ) {
+				$query->set( 'page_id', $post->ID );
+			} else {
+				$query->set( 'p', $post->ID );
+			}
+			$query->queried_object    = $post;
+			$query->queried_object_id = $post->ID;
+			$query->parse_query_vars();
+
+			$availability = AMP_Theme_Support::get_template_availability( $query );
+			if ( $availability instanceof WP_Error && 0 !== count( array_diff( $availability->get_error_codes(), $errors, array( 'post-status-disabled' ) ) ) ) {
+				$errors[] = 'template-unavailable';
+				$status   = self::DISABLED_STATUS;
+			}
+		}
+
 		$labels = array(
 			'enabled'  => __( 'Enabled', 'amp' ),
 			'disabled' => __( 'Disabled', 'amp' ),

includes/amp-helper-functions.php

@@ -239,80 +239,62 @@ function amp_add_amphtml_link() {
  * @see   AMP_Post_Type_Support::get_support_errors()
  *
  * @param WP_Post $post Post.
- *
  * @return bool Whether the post supports AMP.
  */
 function post_supports_amp( $post ) {
-	if ( amp_is_canonical() ) {
-		return true;
-	}
-
-	$errors = AMP_Post_Type_Support::get_support_errors( $post );
-
-	// Return false if an error is found.
-	if ( ! empty( $errors ) ) {
-		return false;
-	}
-
-	switch ( get_post_meta( $post->ID, AMP_Post_Meta_Box::STATUS_POST_META_KEY, true ) ) {
-		case AMP_Post_Meta_Box::ENABLED_STATUS:
-			return true;
-
-		case AMP_Post_Meta_Box::DISABLED_STATUS:
-			return false;
-
-		// Disabled by default for custom page templates, page on front and page for posts.
-		default:
-			$enabled = (
-				! (bool) get_page_template_slug( $post )
-				&&
-				! (
-					'page' === $post->post_type
-					&&
-					'page' === get_option( 'show_on_front' )
-					&&
-					in_array( (int) $post->ID, array(
-						(int) get_option( 'page_on_front' ),
-						(int) get_option( 'page_for_posts' ),
-					), true )
-				)
-			);
-
-			/**
-			 * Filters whether default AMP status should be enabled or not.
-			 *
-			 * @since 0.6
-			 *
-			 * @param string  $status Status.
-			 * @param WP_Post $post   Post.
-			 */
-			return apply_filters( 'amp_post_status_default_enabled', $enabled, $post );
-	}
+	return 0 === count( AMP_Post_Type_Support::get_support_errors( $post ) );
 }
 
 /**
- * Are we currently on an AMP URL?
+ * Determine whether the current response being served as AMP.
  *
- * @since 1.0 This function can be called before the `parse_query` action because the 'amp' query var is specifically and exclusively used when 'amp' theme support is added.
+ * This function cannot be called before the parse_query action because it needs to be able
+ * to determine the queried object is able to be served as AMP.
  *
+ * @see is_header_video_active()
  * @return bool Whether it is the AMP endpoint.
  */
 function is_amp_endpoint() {
+	global $wp_query;
 	if ( is_admin() || is_feed() || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ) {
 		return false;
 	}
 
-	// When 'amp' theme support is (or will be added) then these are the conditions that are key to be checked.
-	if ( amp_is_canonical() || isset( $_GET[ amp_get_slug() ] ) ) { // WPCS: CSRF OK.
-		return true;
+	$did_parse_query = did_action( 'parse_query' );
+
+	if ( ! $did_parse_query ) {
+		_doing_it_wrong( __FUNCTION__, sprintf( esc_html__( "is_amp_endpoint() was called before the 'parse_query' hook was called. This function will always return 'false' before the 'parse_query' hook is called.", 'amp' ) ), '0.4.2' );
 	}
 
-	// Condition for non-theme support when /amp/ endpoint is used.
-	if ( false !== get_query_var( amp_get_slug(), false ) ) {
-		return true;
+	$has_amp_query_var = (
+		isset( $_GET[ amp_get_slug() ] ) // WPCS: CSRF OK.
+		||
+		false !== get_query_var( amp_get_slug(), false )
+	);
+
+	// When there is no query var and AMP is not canonical/native, then this is definitely not an AMP endpoint.
+	if ( ! $has_amp_query_var && ! amp_is_canonical() ) {
+		return false;
 	}
 
-	return false;
+	if ( current_theme_supports( 'amp' ) ) {
+		$template_available = true === AMP_Theme_Support::get_template_availability();
+		return amp_is_canonical() ? $template_available : $has_amp_query_var;
+	} else {
+
+		// Check if the queried object supports AMP.
+		if ( is_singular() || ( $wp_query instanceof WP_Query && $wp_query->is_posts_page ) ) {
+			/**
+			 * Post.
+			 *
+			 * @var WP_Post $queried_object
+			 */
+			$queried_object = get_queried_object();
+			return post_supports_amp( $queried_object );
+		}
+
+		return false; // Legacy templates only support posts via AMP_Post_Template.
+	}
 }
 
 /**

includes/class-amp-post-type-support.php

@@ -14,9 +14,11 @@ class AMP_Post_Type_Support {
 	/**
 	 * Get post types that plugin supports out of the box (which cannot be disabled).
 	 *
+	 * @deprecated
 	 * @return string[] Post types.
 	 */
 	public static function get_builtin_supported_post_types() {
+		_deprecated_function( __METHOD__, '1.0' );
 		return array_filter( array( 'post' ), 'post_type_exists' );
 	}
 
@@ -27,17 +29,12 @@ public static function get_builtin_supported_post_types() {
 	 * @return string[] Post types eligible for AMP.
 	 */
 	public static function get_eligible_post_types() {
-		return array_merge(
-			self::get_builtin_supported_post_types(),
-			array( 'page' ),
-			array_values( get_post_types(
-				array(
-					'public'   => true,
-					'_builtin' => false,
-				),
-				'names'
-			) )
-		);
+		return array_values( get_post_types(
+			array(
+				'public' => true,
+			),
+			'names'
+		) );
 	}
 
 	/**
@@ -49,10 +46,11 @@ public static function get_eligible_post_types() {
 	 * @since 0.6
 	 */
 	public static function add_post_type_support() {
-		$post_types = array_merge(
-			self::get_builtin_supported_post_types(),
-			AMP_Options_Manager::get_option( 'supported_post_types', array() )
-		);
+		if ( current_theme_supports( 'amp' ) && AMP_Options_Manager::get_option( 'all_templates_supported' ) ) {
+			$post_types = self::get_eligible_post_types();
+		} else {
+			$post_types = AMP_Options_Manager::get_option( 'supported_post_types', array() );
+		}
 		foreach ( $post_types as $post_type ) {
 			add_post_type_support( $post_type, amp_get_slug() );
 		}
@@ -72,8 +70,7 @@ public static function get_support_errors( $post ) {
 		}
 		$errors = array();
 
-		// Because `add_rewrite_endpoint` doesn't let us target specific post_types.
-		if ( isset( $post->post_type ) && ! post_type_supports( $post->post_type, amp_get_slug() ) ) {
+		if ( ! post_type_supports( $post->post_type, amp_get_slug() ) ) {
 			$errors[] = 'post-type-support';
 		}
 
@@ -94,6 +91,48 @@ public static function get_support_errors( $post ) {
 			$errors[] = 'skip-post';
 		}
 
+		$status = get_post_meta( $post->ID, AMP_Post_Meta_Box::STATUS_POST_META_KEY, true );
+		if ( $status ) {
+			if ( AMP_Post_Meta_Box::DISABLED_STATUS === $status ) {
+				$errors[] = 'post-status-disabled';
+			}
+		} else {
+			/*
+			 * Disabled by default for custom page templates, page on front and page for posts, unless 'amp' theme
+			 * support is present (in which case AMP_Theme_Support::get_template_availability() determines availability).
+			 */
+			$enabled = (
+				current_theme_supports( 'amp' )
+				||
+				(
+					! (bool) get_page_template_slug( $post )
+					&&
+					! (
+						'page' === $post->post_type
+						&&
+						'page' === get_option( 'show_on_front' )
+						&&
+						in_array( (int) $post->ID, array(
+							(int) get_option( 'page_on_front' ),
+							(int) get_option( 'page_for_posts' ),
+						), true )
+					)
+				)
+			);
+
+			/**
+			 * Filters whether default AMP status should be enabled or not.
+			 *
+			 * @since 0.6
+			 *
+			 * @param string  $status Status.
+			 * @param WP_Post $post   Post.
+			 */
+			$enabled = apply_filters( 'amp_post_status_default_enabled', $enabled, $post );
+			if ( ! $enabled ) {
+				$errors[] = 'post-status-disabled';
+			}
+		}
 		return $errors;
 	}
 }