fix: preserve selected page state across the maintenance mode lifecycle

.github/workflows/test-php.yml

@@ -70,7 +70,7 @@ jobs:
           # the latest WordPress test suite requires PHP 7.4+
           php-version: '7.4'
           extensions: simplexml, mysql
-          tools: phpunit:7.5.20, phpunit-polyfills
+          tools: phpunit-polyfills
       - name: Checkout source code
         uses: actions/checkout@v2
       - name: Install Subversion

includes/classes/wp-maintenance-mode-admin.php

@@ -686,13 +686,29 @@ public function select_page() {
 				die( esc_html__( 'Security check.', 'wp-maintenance-mode' ) );
 			}
 
-			$this->plugin_settings['design']['page_id'] = $_POST['page_id'];
-			wp_update_post(
-				array(
-					'ID'            => $this->plugin_settings['design']['page_id'],
-					'page_template' => 'templates/wpmm-page-template.php',
-				)
-			);
+			$page_id = isset( $_POST['page_id'] ) ? absint( $_POST['page_id'] ) : 0;
+
+			$previous_page_id = isset( $this->plugin_settings['design']['page_id'] ) ? absint( $this->plugin_settings['design']['page_id'] ) : 0;
+
+			if ( $previous_page_id && $previous_page_id !== $page_id ) {
+				// hand the previously selected page back before abandoning it,
+				// otherwise nothing would ever restore it
+				wpmm_restore_page_state( $previous_page_id );
+			}
+
+			$this->plugin_settings['design']['page_id'] = $page_id;
+
+			if ( $page_id ) {
+				// remember the page's original state before taking it over as a maintenance page
+				wpmm_record_page_state( $page_id );
+
+				wp_update_post(
+					array(
+						'ID'            => $page_id,
+						'page_template' => 'templates/wpmm-page-template.php',
+					)
+				);
+			}
 
 			update_option( 'wpmm_settings', $this->plugin_settings );
 
@@ -721,9 +737,19 @@ public function insert_template() {
 				die( esc_html__( 'Security check.', 'wp-maintenance-mode' ) );
 			}
 
-			$template_slug = $_POST['template_slug'];
-			$category      = $_POST['category'];
-			$template      = json_decode( file_get_contents( WPMM_TEMPLATES_PATH . $category . '/' . $template_slug . '/blocks-export.json' ) );
+			$template_slug = isset( $_POST['template_slug'] ) ? basename( sanitize_text_field( $_POST['template_slug'] ) ) : '';
+			$category      = isset( $_POST['category'] ) ? basename( sanitize_text_field( $_POST['category'] ) ) : '';
+			$template_file = WPMM_TEMPLATES_PATH . $category . '/' . $template_slug . '/blocks-export.json';
+
+			if ( '' === $template_slug || '' === $category || ! is_readable( $template_file ) ) {
+				wp_send_json_error( array( 'error' => 'Unknown template' ) );
+			}
+
+			$template = json_decode( file_get_contents( $template_file ) );
+
+			if ( empty( $template->content ) ) {
+				wp_send_json_error( array( 'error' => 'Unknown template' ) );
+			}
 
 			$blocks = str_replace( '\n', '', $template->content );
 
@@ -734,20 +760,36 @@ public function insert_template() {
 				'page_template' => 'templates/wpmm-page-template.php',
 			);
 
-			if ( isset( $this->plugin_settings['design']['page_id'] ) && get_post_status( $this->plugin_settings['design']['page_id'] ) && get_post_status( $this->plugin_settings['design']['page_id'] ) !== 'trash' ) {
-				$post_arr['ID'] = $this->plugin_settings['design']['page_id'];
+			$selected_page_id = isset( $this->plugin_settings['design']['page_id'] ) ? absint( $this->plugin_settings['design']['page_id'] ) : 0;
+			$page_exists      = $selected_page_id && get_post_status( $selected_page_id ) && get_post_status( $selected_page_id ) !== 'trash';
+
+			if ( $page_exists && get_post_meta( $selected_page_id, '_wpmm_generated', true ) ) {
+				// only pages created by the plugin may be overwritten
+				$post_arr['ID'] = $selected_page_id;
 				$page_id        = wp_update_post( $post_arr );
 			} else {
+				if ( $page_exists ) {
+					// hand the user's page back before switching to a generated one
+					wpmm_restore_page_state( $selected_page_id );
+				}
+
 				$post_arr['post_title'] = __( 'Maintenance Page', 'wp-maintenance-mode' );
 				$page_id                = wp_insert_post( $post_arr );
+
+				if ( $page_id ) {
+					update_post_meta( $page_id, '_wpmm_generated', 1 );
+				}
 			}
 
 			if ( $page_id === 0 || $page_id instanceof WP_Error ) {
 				wp_send_json_error( array( 'error' => 'Could not get the page' ) );
 			}
 
 			$this->plugin_settings['design']['page_id'] = $page_id;
-			CSS_Handler::generate_css_file( $page_id );
+
+			if ( class_exists( 'ThemeIsle\GutenbergBlocks\CSS\CSS_Handler' ) ) {
+				CSS_Handler::generate_css_file( $page_id );
+			}
 
 			if ( 'wizard' === $_POST['source'] ) {
 				$this->plugin_settings['general']['status'] = 1;

includes/classes/wp-maintenance-mode.php

@@ -97,12 +97,27 @@ private function __construct() {
 				add_action( 'wp_ajax_wpmm_send_contact', array( $this, 'send_contact' ) );
 				add_action( 'otter_form_after_submit', array( $this, 'otter_add_subscriber' ) );
 
-				if ( isset( $this->plugin_settings['design']['page_id'] ) && get_option( 'wpmm_new_look' ) && get_post_status( $this->plugin_settings['design']['page_id'] ) === 'private' ) {
-					add_filter( 'wpo_purge_all_cache_on_update', '__return_true' );
-					if ( function_exists( 'wp_functionality_constants' ) ) {
-						wp_functionality_constants();
+				$maintenance_page_status = isset( $this->plugin_settings['design']['page_id'] ) ? get_post_status( $this->plugin_settings['design']['page_id'] ) : false;
+
+				if ( $maintenance_page_status && $maintenance_page_status !== 'trash' && get_option( 'wpmm_new_look' ) ) {
+					// remember the page's original state so it can be restored when maintenance mode is disabled
+					wpmm_record_page_state( (int) $this->plugin_settings['design']['page_id'] );
+
+					if ( get_post_meta( $this->plugin_settings['design']['page_id'], '_wp_page_template', true ) !== 'templates/wpmm-page-template.php' ) {
+						update_post_meta( $this->plugin_settings['design']['page_id'], '_wp_page_template', 'templates/wpmm-page-template.php' );
+					}
+
+					if ( get_post_status( $this->plugin_settings['design']['page_id'] ) === 'private' ) {
+						add_filter( 'wpo_purge_all_cache_on_update', '__return_true' );
+						if ( function_exists( 'wp_functionality_constants' ) ) {
+							wp_functionality_constants();
+						}
+						wp_publish_post( $this->plugin_settings['design']['page_id'] );
+
+						// mark the publish as plugin-made, so restore can tell it apart
+						// from a status the user chose deliberately
+						update_post_meta( $this->plugin_settings['design']['page_id'], '_wpmm_applied_status', 'publish' );
 					}
-					wp_publish_post( $this->plugin_settings['design']['page_id'] );
 				}
 
 				update_option( 'show_on_front', 'page' );
@@ -141,21 +156,14 @@ function ( $value ) {
 				add_action( 'wpmm_before_scripts', array( $this, 'add_bot_extras' ) );
 				add_action( 'wpmm_footer', array( $this, 'add_js_files' ) );
 			} else {
-				// make maintenance page private when maintenance mode is disabled
+				// restore the maintenance page to its original state when maintenance mode is disabled
 				add_action(
 					'init',
 					function () {
 						if ( ! isset( $this->plugin_settings['design']['page_id'] ) ) {
 							return;
 						}
-						if ( get_post_status( $this->plugin_settings['design']['page_id'] ) === 'publish' ) {
-							wp_update_post(
-								array(
-									'ID'          => $this->plugin_settings['design']['page_id'],
-									'post_status' => 'private',
-								)
-							);
-						}
+						wpmm_restore_page_state( (int) $this->plugin_settings['design']['page_id'] );
 					}
 				);
 			}
@@ -670,6 +678,12 @@ public static function single_activate( $network_wide = false ) {
 		 * @since 2.0.0
 		 */
 		public static function single_deactivate() {
+			// give the selected page back to the site in its original state
+			$settings = get_option( 'wpmm_settings' );
+			if ( ! empty( $settings['design']['page_id'] ) ) {
+				wpmm_restore_page_state( (int) $settings['design']['page_id'] );
+			}
+
 			wpmm_delete_cache();
 		}
 

includes/functions/helpers.php

@@ -513,6 +513,91 @@ function sanitize_hex_color( $color ) {
 	}
 }
 
+/**
+ * Record the current state of the selected maintenance page so it can be
+ * restored when maintenance mode is disabled or the plugin is deactivated.
+ *
+ * A previously recorded state is never overwritten: the page may already be
+ * carrying plugin-made changes, and recording those would poison the original
+ * state. The record is cleared when the page is restored.
+ *
+ * @since 2.6.23
+ * @param int $page_id page ID
+ * @return void
+ */
+function wpmm_record_page_state( $page_id ) {
+	$status = get_post_status( $page_id );
+
+	if ( ! $status ) {
+		return;
+	}
+
+	$template = get_post_meta( $page_id, '_wp_page_template', true );
+
+	// a selection carried over from an old release already wears the plugin's
+	// template; recording that would make the takeover permanent
+	if ( $template === 'templates/wpmm-page-template.php' ) {
+		$template = '';
+	}
+
+	// a single first-write-wins meta keeps the record atomic: a racing request
+	// can neither save the plugin-modified state nor observe half a record
+	add_post_meta(
+		$page_id,
+		'_wpmm_original_state',
+		array(
+			'status'   => $status,
+			'template' => $template,
+		),
+		true
+	);
+}
+
+/**
+ * Restore the selected maintenance page to its recorded original state.
+ * Pages without a recorded state are left untouched.
+ *
+ * The status is only put back while the page still carries the status the
+ * plugin applied: any other status — trash included — was the user's own
+ * doing and expresses intent the record predates.
+ *
+ * @since 2.6.23
+ * @param int $page_id page ID
+ * @return void
+ */
+function wpmm_restore_page_state( $page_id ) {
+	$state = get_post_meta( $page_id, '_wpmm_original_state', true );
+
+	if ( empty( $state ) || ! is_array( $state ) || ! get_post( $page_id ) ) {
+		return;
+	}
+
+	$original_status = isset( $state['status'] ) ? $state['status'] : '';
+	$applied_status  = get_post_meta( $page_id, '_wpmm_applied_status', true );
+	$current_status  = get_post_status( $page_id );
+
+	if ( $original_status && $applied_status && $current_status === $applied_status && $current_status !== $original_status ) {
+		wp_update_post(
+			array(
+				'ID'          => $page_id,
+				'post_status' => $original_status,
+			)
+		);
+	}
+
+	$original_template = isset( $state['template'] ) ? $state['template'] : '';
+
+	if ( empty( $original_template ) ) {
+		delete_post_meta( $page_id, '_wp_page_template' );
+	} else {
+		update_post_meta( $page_id, '_wp_page_template', $original_template );
+	}
+
+	// clear the record so the next take-over captures the page's state afresh
+	delete_post_meta( $page_id, '_wpmm_original_state' );
+	delete_post_meta( $page_id, '_wpmm_applied_status' );
+}
+
 /**
  * Get option page URL.
  */