Improved page default status logic and add overwrite ability; ensure front page and page for posts can be served as AMP when enabled

amp.php

@@ -75,6 +75,7 @@ function amp_after_setup_theme() {
 	add_filter( 'amp_post_template_analytics', 'amp_add_custom_analytics' );
 	add_action( 'wp_loaded', 'amp_post_meta_box' );
 	add_action( 'wp_loaded', 'amp_add_options_menu' );
+	add_action( 'parse_query', 'amp_correct_query_when_is_front_page' );
 	AMP_Post_Type_Support::add_post_type_support();
 }
 add_action( 'after_setup_theme', 'amp_after_setup_theme', 5 );
@@ -117,22 +118,69 @@ function amp_force_query_var_value( $query_vars ) {
 	return $query_vars;
 }
 
+/**
+ * Fix up WP_Query for front page when amp query var is present.
+ *
+ * Normally the front page would not get served if a query var is present other than preview, page, paged, and cpage.
+ *
+ * @since 0.6
+ * @see WP_Query::parse_query()
+ * @link https://github.com/WordPress/wordpress-develop/blob/0baa8ae85c670d338e78e408f8d6e301c6410c86/src/wp-includes/class-wp-query.php#L951-L971
+ *
+ * @param WP_Query $query Query.
+ */
+function amp_correct_query_when_is_front_page( WP_Query $query ) {
+	$is_front_page_query = (
+		$query->is_main_query()
+		&&
+		$query->is_home()
+		&&
+		// Is AMP endpoint.
+		false !== $query->get( AMP_QUERY_VAR, false )
+		&&
+		// Is query not yet fixed uo up to be front page.
+		! $query->is_front_page()
+		&&
+		// Is showing pages on front.
+		'page' === get_option( 'show_on_front' )
+		&&
+		// Has page on front set.
+		get_option( 'page_on_front' )
+		&&
+		// See line in WP_Query::parse_query() at <https://github.com/WordPress/wordpress-develop/blob/0baa8ae/src/wp-includes/class-wp-query.php#L961>.
+		0 === count( array_diff( array_keys( wp_parse_args( $query->query ) ), array( AMP_QUERY_VAR, 'preview', 'page', 'paged', 'cpage' ) ) )
+	);
+	if ( $is_front_page_query ) {
+		$query->is_home     = false;
+		$query->is_page     = true;
+		$query->is_singular = true;
+		$query->set( 'page_id', get_option( 'page_on_front' ) );
+	}
+}
+
+/**
+ * Add AMP actions when the request can be served as AMP.
+ *
+ * Actions will only be added if the request is for a singular post (including front page and page for posts), excluding feeds.
+ *
+ * @since 0.2
+ */
 function amp_maybe_add_actions() {
-	if ( ! is_singular() || is_feed() ) {
+	global $wp_query;
+	if ( ! ( is_singular() || $wp_query->is_posts_page ) || is_feed() ) {
 		return;
 	}
-
 	$is_amp_endpoint = is_amp_endpoint();
 
-	// Cannot use `get_queried_object` before canonical redirect; see https://core.trac.wordpress.org/ticket/35344
-	global $wp_query;
-	$post = $wp_query->post;
-
-	$supports = post_supports_amp( $post );
-
-	if ( ! $supports ) {
+	/**
+	 * Queried post object.
+	 *
+	 * @var WP_Post $post
+	 */
+	$post = get_queried_object();
+	if ( ! post_supports_amp( $post ) ) {
 		if ( $is_amp_endpoint ) {
-			wp_safe_redirect( get_permalink( $post->ID ), 301 );
+			wp_safe_redirect( get_permalink( $post->ID ), 302 ); // Temporary redirect because AMP may be supported in future.
 			exit;
 		}
 		return;

assets/js/amp-post-meta-box.js

@@ -19,7 +19,8 @@ var ampPostMetaBox = ( function( $ ) {
 		 */
 		data: {
 			previewLink: '',
-			disabled: false,
+			enabled: true, // Overridden by post_supports_amp( $post ).
+			canSupport: true, // Overridden by count( AMP_Post_Type_Support::get_support_errors( $post ) ) === 0.
 			statusInputName: '',
 			l10n: {
 				ampPreviewBtnLabel: ''
@@ -58,7 +59,8 @@ var ampPostMetaBox = ( function( $ ) {
 	component.boot = function boot( data ) {
 		component.data = data;
 		$( document ).ready( function() {
-			if ( ! component.data.disabled ) {
+			component.statusRadioInputs = $( '[name="' + component.data.statusInputName + '"]' );
+			if ( component.data.enabled ) {
 				component.addPreviewButton();
 			}
 			component.listen();
@@ -77,8 +79,10 @@ var ampPostMetaBox = ( function( $ ) {
 			component.onAmpPreviewButtonClick();
 		} );
 
+		component.statusRadioInputs.prop( 'disabled', true ); // Prevent cementing setting default status as overridden status.
 		$( '.edit-amp-status, [href="#amp_status"]' ).click( function( e ) {
 			e.preventDefault();
+			component.statusRadioInputs.prop( 'disabled', false );
 			component.toggleAmpStatus( $( e.target ) );
 		} );
 
@@ -147,7 +151,7 @@ var ampPostMetaBox = ( function( $ ) {
 
 		// Don't modify status on cancel button click.
 		if ( ! $target.hasClass( 'button-cancel' ) ) {
-			status = $( '[name="' + component.data.statusInputName + '"]:checked' ).val();
+			status = component.statusRadioInputs.filter( ':checked' ).val();
 		}
 
 		$checked = $( '#amp-status-' + status );
@@ -161,7 +165,7 @@ var ampPostMetaBox = ( function( $ ) {
 		$container.slideToggle( component.toggleSpeed );
 
 		// Update status.
-		if ( ! component.data.disabled ) {
+		if ( component.data.canSupport ) {
 			$container.data( 'amp-status', status );
 			$checked.prop( 'checked', true );
 			$( '.amp-status-text' ).text( $checked.next().text() );

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

@@ -22,12 +22,28 @@ class AMP_Post_Meta_Box {
 	const ASSETS_HANDLE = 'amp-post-meta-box';
 
 	/**
-	 * The post meta key for whether the post is skipped.
+	 * The enabled status post meta value.
 	 *
 	 * @since 0.6
 	 * @var string
 	 */
-	const DISABLED_POST_META_KEY = 'amp_disabled';
+	const ENABLED_STATUS = 'enabled';
+
+	/**
+	 * The disabled status post meta value.
+	 *
+	 * @since 0.6
+	 * @var string
+	 */
+	const DISABLED_STATUS = 'disabled';
+
+	/**
+	 * The status post meta key.
+	 *
+	 * @since 0.6
+	 * @var string
+	 */
+	const STATUS_POST_META_KEY = 'amp_status';
 
 	/**
 	 * The field name for the enabled/disabled radio buttons.
@@ -59,32 +75,38 @@ class AMP_Post_Meta_Box {
 	 * @since 0.6
 	 */
 	public function init() {
+		register_meta( 'post', self::STATUS_POST_META_KEY, array(
+			'sanitize_callback' => array( $this, 'sanitize_status' ),
+			'type'              => 'string',
+			'description'       => __( 'AMP status.', 'amp' ),
+			'show_in_rest'      => true,
+			'single'            => true,
+		) );
+
 		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_admin_assets' ) );
 		add_action( 'post_submitbox_misc_actions', array( $this, 'render_status' ) );
 		add_action( 'save_post', array( $this, 'save_amp_status' ) );
 		add_filter( 'preview_post_link', array( $this, 'preview_post_link' ) );
 	}
 
 	/**
-	 * Get whether AMP is available for a given post.
-	 *
-	 * This is just calling `post_supports_amp()` but ignoring any user-supplied opt-out for AMP.
+	 * Sanitize status.
 	 *
-	 * @since 0.6
-	 * @see post_supports_amp()
-	 *
-	 * @param WP_Post $post Post.
-	 * @return bool Whether or not AMP is available.
+	 * @param string $status Status.
+	 * @return string Sanitized status. Empty string when invalid.
 	 */
-	protected function is_amp_available( $post ) {
-		$support_errors = AMP_Post_Type_Support::get_support_errors( $post );
-		if ( empty( $support_errors ) ) {
-			return true;
-		}
-		if ( 1 === count( $support_errors ) && 'post-disabled' === $support_errors[0] ) {
-			return true;
+	public function sanitize_status( $status ) {
+		$status = strtolower( trim( $status ) );
+		if ( ! in_array( $status, array( 'enabled', 'disabled' ), true ) ) {
+			/*
+			 * In lieu of actual validation being available, clear the status entirely
+			 * so that the underlying default status will be used instead.
+			 * In the future it would be ideal if register_meta() accepted a
+			 * validate_callback as well which the REST API could leverage.
+			 */
+			$status = '';
 		}
-		return false;
+		return $status;
 	}
 
 	/**
@@ -122,7 +144,8 @@ public function enqueue_admin_assets() {
 		wp_add_inline_script( self::ASSETS_HANDLE, sprintf( 'ampPostMetaBox.boot( %s );',
 			wp_json_encode( array(
 				'previewLink'     => esc_url_raw( add_query_arg( AMP_QUERY_VAR, '', get_preview_post_link( $post ) ) ),
-				'disabled'        => (bool) get_post_meta( $post->ID, self::DISABLED_POST_META_KEY, true ) || ! $this->is_amp_available( $post ),
+				'enabled'         => post_supports_amp( $post ),
+				'canSupport'      => count( AMP_Post_Type_Support::get_support_errors( $post ) ) === 0,
 				'statusInputName' => self::STATUS_INPUT_NAME,
 				'l10n'            => array(
 					'ampPreviewBtnLabel' => __( 'Preview changes in AMP (opens in new window)', 'amp' ),
@@ -148,10 +171,9 @@ public function render_status( $post ) {
 			return;
 		}
 
-		$available = $this->is_amp_available( $post );
-		$disabled  = (bool) get_post_meta( $post->ID, self::DISABLED_POST_META_KEY, true );
-		$status    = $disabled || ! $available ? 'disabled' : 'enabled';
-		$labels    = array(
+		$errors = AMP_Post_Type_Support::get_support_errors( $post );
+		$status = post_supports_amp( $post ) ? self::ENABLED_STATUS : self::DISABLED_STATUS;
+		$labels = array(
 			'enabled'  => __( 'Enabled', 'amp' ),
 			'disabled' => __( 'Disabled', 'amp' ),
 		);
@@ -182,11 +204,11 @@ public function save_amp_status( $post_id ) {
 		);
 
 		if ( true === $verify ) {
-			if ( 'disabled' === $_POST[ self::STATUS_INPUT_NAME ] ) {
-				update_post_meta( $post_id, self::DISABLED_POST_META_KEY, true );
-			} else {
-				delete_post_meta( $post_id, self::DISABLED_POST_META_KEY );
-			}
+			update_post_meta(
+				$post_id,
+				self::STATUS_POST_META_KEY,
+				$_POST[ self::STATUS_INPUT_NAME ] // Note: The sanitize_callback has been supplied in the register_meta() call above.
+			);
 		}
 	}
 

includes/amp-helper-functions.php

@@ -55,15 +55,55 @@ function amp_get_permalink( $post_id ) {
  * Determine whether a given post supports AMP.
  *
  * @since 0.1
- * @since 0.6 Returns false when post has meta to disable AMP or when page is homepage or page for posts.
+ * @since 0.6 Returns false when post has meta to disable AMP.
  * @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 ) {
-	return 0 === count( AMP_Post_Type_Support::get_support_errors( $post ) );
+	$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 );
+	}
 }
 
 /**

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

@@ -17,7 +17,7 @@ class AMP_Post_Type_Support {
 	 * @return string[] Post types.
 	 */
 	public static function get_builtin_supported_post_types() {
-		return array_filter( array( 'post', 'page' ), 'post_type_exists' );
+		return array_filter( array( 'post' ), 'post_type_exists' );
 	}
 
 	/**
@@ -29,6 +29,7 @@ public static function get_builtin_supported_post_types() {
 	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,
@@ -76,20 +77,6 @@ public static function get_support_errors( $post ) {
 			$errors[] = 'post-type-support';
 		}
 
-		// Skip based on postmeta.
-		if ( ! isset( $post->ID ) || (bool) get_post_meta( $post->ID, AMP_Post_Meta_Box::DISABLED_POST_META_KEY, true ) ) {
-			$errors[] = 'post-disabled';
-		}
-
-		// Homepage and page for posts are not supported yet.
-		if ( 'page' === get_post_type( $post ) && 'page' === get_option( 'show_on_front' ) ) {
-			if ( (int) get_option( 'page_for_posts' ) === (int) $post->ID ) {
-				$errors[] = 'page-for-posts';
-			} elseif ( (int) get_option( 'page_on_front' ) === (int) $post->ID ) {
-				$errors[] = 'page-on-front';
-			}
-		}
-
 		if ( post_password_required( $post ) ) {
 			$errors[] = 'password-protected';
 		}

includes/templates/class-amp-post-template.php

@@ -199,7 +199,8 @@ public function get_customizer_setting( $name, $default = null ) {
 	 * Load and print the template parts for the given post.
 	 */
 	public function load() {
-		$template = is_page() ? 'page' : 'single';
+		global $wp_query;
+		$template = is_page() || $wp_query->is_posts_page ? 'page' : 'single';
 		$this->load_parts( array( $template ) );
 	}