Let Gutenberg be default editor for posts with blocks; add links to classic editor

lib/register.php

@@ -62,6 +62,62 @@ function gutenberg_menu() {
 }
 add_action( 'admin_menu', 'gutenberg_menu' );
 
+/**
+ * Provide an edit link for posts and terms.
+ *
+ * @since 0.5.0
+ *
+ * @param WP_Admin_Bar $wp_admin_bar Admin bar.
+ */
+function gutenberg_add_admin_bar_edit_link( $wp_admin_bar ) {
+	$edit_node = $wp_admin_bar->get_node( 'edit' );
+	if ( ! $edit_node ) {
+		return;
+	}
+
+	$queried_object = get_queried_object();
+	if ( empty( $queried_object ) || empty( $queried_object->post_type ) || ! post_type_exists( $queried_object->post_type ) || ! gutenberg_can_edit_post( $queried_object->ID ) ) {
+		return;
+	}
+	$post = $queried_object;
+
+	if ( ! get_post_type_object( $post->post_type )->show_in_admin_bar ) {
+		return;
+	}
+
+	$classic_text = __( 'Edit in Classic Editor', 'gutenberg' );
+	remove_filter( 'get_edit_post_link', 'gutenberg_filter_edit_post_link', 10 );
+	$classic_url = get_edit_post_link( $post->ID, 'raw' );
+	add_filter( 'get_edit_post_link', 'gutenberg_filter_edit_post_link', 10, 3 );
+
+	if ( empty( $classic_url ) || ! post_type_supports( $post->post_type, 'editor' ) ) {
+		return;
+	}
+
+	$gutenberg_text = __( 'Edit in Gutenberg', 'gutenberg' );
+	$gutenberg_url = gutenberg_get_edit_post_url( $post->ID );
+
+	$is_gutenberg_default = gutenberg_post_has_blocks( $post->ID );
+
+	// Update title for edit link to indicate default editor.
+	$wp_admin_bar->add_node( array_merge(
+		(array) $edit_node,
+		array(
+			'title' => $is_gutenberg_default ? $gutenberg_text : $classic_text,
+		)
+	) );
+
+	// Add submenu item under link to go to Gutenberg editor or classic editor.
+	$wp_admin_bar->add_node( array(
+		'id' => 'edit_alt',
+		'parent' => 'edit',
+		'href' => $is_gutenberg_default ? $classic_url : $gutenberg_url,
+		'title' => $is_gutenberg_default ? $classic_text : $gutenberg_text,
+	) );
+
+}
+add_action( 'admin_bar_menu', 'gutenberg_add_admin_bar_edit_link', 81 );
+
 /**
  * Adds the filters to register additional links for the Gutenberg editor in
  * the post/page screens.
@@ -82,39 +138,146 @@ function gutenberg_add_edit_links_filters() {
  *
  * @since 0.1.0
  *
- * @param  array $actions Post actions.
- * @param  array $post    Edited post.
+ * @param  array   $actions Post actions.
+ * @param  WP_Post $post    Edited post.
  *
  * @return array          Updated post actions.
  */
 function gutenberg_add_edit_links( $actions, $post ) {
-	$can_edit_post = current_user_can( 'edit_post', $post->ID );
-	$title = _draft_or_post_title( $post->ID );
-	$post_type = get_post_type( $post );
+	if ( ! gutenberg_can_edit_post( $post->ID ) ||
+			'trash' === $post->post_status ||
+			! post_type_supports( $post->post_type, 'editor' ) ||
+			! apply_filters( 'gutenberg_add_edit_link_for_post_type', true, $post->post_type, $post ) ) {
+		return $actions;
+	}
 
-	if ( $can_edit_post && 'trash' !== $post->post_status && apply_filters( 'gutenberg_add_edit_link_for_post_type', true, $post_type, $post ) ) {
-		// Build the Gutenberg edit action. See also: WP_Posts_List_Table::handle_row_actions().
-		$gutenberg_url = menu_page_url( 'gutenberg', false );
-		$gutenberg_action = sprintf(
+	if ( gutenberg_post_has_blocks( $post->ID ) ) {
+		remove_filter( 'get_edit_post_link', 'gutenberg_filter_edit_post_link', 10 );
+		add_filter( 'get_edit_post_link', 'gutenberg_filter_edit_post_link', 10, 3 );
+	}
+
+	// Build the new edit actions. See also: WP_Posts_List_Table::handle_row_actions().
+	$title = _draft_or_post_title( $post->ID );
+	$edit_actions = array(
+		'classic hide-if-no-js' => sprintf(
 			'<a href="%s" aria-label="%s">%s</a>',
-			add_query_arg( 'post_id', $post->ID, $gutenberg_url ),
+			esc_url( get_edit_post_link( $post->ID, 'raw' ) ),
+			esc_attr( sprintf(
+				/* translators: %s: post title */
+				__( 'Edit &#8220;%s&#8221; in the classic editor', 'gutenberg' ),
+				$title
+			) ),
+			__( 'Classic Editor', 'gutenberg' )
+		),
+		'gutenberg hide-if-no-js' => sprintf(
+			'<a href="%s" aria-label="%s">%s</a>',
+			esc_url( gutenberg_get_edit_post_url( $post->ID ) ),
 			esc_attr( sprintf(
 				/* translators: %s: post title */
 				__( 'Edit &#8220;%s&#8221; in the Gutenberg editor', 'gutenberg' ),
 				$title
 			) ),
 			__( 'Gutenberg', 'gutenberg' )
-		);
-		// Insert the Gutenberg action immediately after the Edit action.
-		$edit_offset = array_search( 'edit', array_keys( $actions ), true );
-		$actions = array_merge(
-			array_slice( $actions, 0, $edit_offset + 1 ),
-			array(
-				'gutenberg hide-if-no-js' => $gutenberg_action,
-			),
-			array_slice( $actions, $edit_offset + 1 )
-		);
-	}
+		),
+	);
+
+	// Insert the new actions in place of the Edit action.
+	$edit_offset = array_search( 'edit', array_keys( $actions ), true );
+	$actions = array_merge(
+		array_slice( $actions, 0, $edit_offset ),
+		$edit_actions,
+		array_slice( $actions, $edit_offset + 1 )
+	);
 
 	return $actions;
 }
+
+/**
+ * Get the edit post URL for Gutenberg.
+ *
+ * @since 0.5.0
+ *
+ * @param int $post_id Post ID.
+ * @return string|false URL or false if not available.
+ */
+function gutenberg_get_edit_post_url( $post_id ) {
+	// Note that menu_page_url() cannot be used because it does not work on the frontend.
+	$gutenberg_url = admin_url( 'admin.php?page=gutenberg' );
+	$gutenberg_url = add_query_arg( 'post_id', $post_id, $gutenberg_url );
+	return $gutenberg_url;
+}
+
+/**
+ * Filters the post edit link to default to the Gutenberg editor when the post content contains a block.
+ *
+ * @since 0.5.0
+ *
+ * @param string $url     The edit link URL.
+ * @param int    $post_id Post ID.
+ * @param string $context The link context. If set to 'display' then ampersands are encoded.
+ * @return string Edit post link.
+ */
+function gutenberg_filter_edit_post_link( $url, $post_id, $context ) {
+	$post = get_post( $post_id );
+	if ( gutenberg_can_edit_post( $post_id ) && gutenberg_post_has_blocks( $post_id ) && post_type_supports( get_post_type( $post_id ), 'editor' ) ) {
+		$gutenberg_url = gutenberg_get_edit_post_url( $post->ID );
+		if ( 'display' === $context ) {
+			$gutenberg_url = esc_url( $gutenberg_url );
+		}
+		$url = $gutenberg_url;
+	}
+	return $url;
+}
+add_filter( 'get_edit_post_link', 'gutenberg_filter_edit_post_link', 10, 3 );
+
+/**
+ * Return whether the post can be edited in Gutenberg and by the current user.
+ *
+ * Gutenberg depends on the REST API, and if the post type is not shown in the
+ * REST API, then the post cannot be edited in Gutenberg.
+ *
+ * @since 0.5.0
+ *
+ * @param int $post_id Post.
+ * @return bool Whether the post can be edited with Gutenberg.
+ */
+function gutenberg_can_edit_post( $post_id ) {
+	$post = get_post( $post_id );
+	if ( ! $post || ! post_type_exists( $post->post_type ) ) {
+		return false;
+	}
+	$post_type_object = get_post_type_object( $post->post_type );
+	if ( ! $post_type_object->show_in_rest ) {
+		return false;
+	}
+	return current_user_can( 'edit_post', $post_id );
+}
+
+/**
+ * Determine whether a post has blocks.
+ *
+ * @since 0.5.0
+ *
+ * @param int $post_id Post ID.
+ * @return bool Whether the post has blocks.
+ */
+function gutenberg_post_has_blocks( $post_id ) {
+	$post = get_post( $post_id );
+	return $post && strpos( $post->post_content, '<!-- wp:' ) !== false;
+}
+
+/**
+ * Adds a "Gutenberg" post state for post tables, if the post contains blocks.
+ *
+ * @param  array   $post_states An array of post display states.
+ * @param  WP_Post $post        The current post object.
+ * @return array                A filtered array of post display states.
+ */
+function gutenberg_add_gutenberg_post_state( $post_states, $post ) {
+	if ( gutenberg_post_has_blocks( $post->ID ) ) {
+		$post_states[] = 'Gutenberg';
+	}
+
+	return $post_states;
+}
+add_filter( 'display_post_states', 'gutenberg_add_gutenberg_post_state', 10, 2 );