allow pretty permalinks to be handled for rest endpoints by default

bypass the issue with bad string replacement by just parsing pretty permalinks natively for rest endpoints even when pretty permalinks aren't active

Author: jazzsequence

web/app/mu-plugins/filters.php

@@ -3,7 +3,7 @@
  * Plugin Name: Pantheon WordPress Filters
  * Plugin URI:   https://github.com/pantheon-systems/wordpress-composer-managed
  * Description:  Filters for Composer-managed WordPress sites on Pantheon.
- * Version:      1.2.2
+ * Version:      1.2.3
  * Author:       Pantheon Systems
  * Author URI:   https://pantheon.io/
  * License:      MIT License
@@ -235,3 +235,149 @@ function __rebuild_url_from_parts( array $parts ) : string {
 		( isset( $parts['fragment'] ) ? str_replace( '/', '', "#{$parts['fragment']}" ) : '' )
 	);
 }
+
+/**
+ * REST API Plain Permalink Fix
+ *
+ * Extracts the REST API endpoint from a potentially malformed path.
+ * Handles cases like /wp-json/v2/posts or /wp-json/wp/v2/posts.
+ *
+ * @since 1.2.3
+ * @param string $path The URL path component.
+ * @return string The extracted endpoint (e.g., /v2/posts) or '/'.
+ */
+function __extract_rest_endpoint( string $path ) : string {
+	$rest_route = '/'; // Default to base route
+	$wp_json_pos = strpos( $path, '/wp-json/' );
+
+	if ( $wp_json_pos !== false ) {
+		$extracted_route = substr( $path, $wp_json_pos + strlen( '/wp-json' ) ); // Get everything after /wp-json
+		// Special case: Handle the originally reported '/wp-json/wp/' malformation
+		if ( strpos( $extracted_route, 'wp/' ) === 0 ) {
+			$extracted_route = substr( $extracted_route, strlen( 'wp' ) ); // Remove the extra 'wp'
+		}
+		// Ensure the extracted route starts with a slash
+		if ( ! $extracted_route && $extracted_route[0] !== '/' ) {
+			$extracted_route = '/' . $extracted_route;
+		}
+		$rest_route = $extracted_route ?: '/'; // Use extracted route or default to base
+	}
+	return $rest_route;
+}
+
+/**
+ * Builds the correct plain permalink REST URL.
+ *
+ * @since 1.2.3
+ * @param string $endpoint The REST endpoint (e.g., /v2/posts).
+ * @param string|null $query_str The original query string (or null).
+ * @param string|null $fragment The original fragment (or null).
+ * @return string The fully constructed plain permalink REST URL.
+ */
+function __build_plain_rest_url( string $endpoint, ?string $query_str, ?string $fragment ) : string {
+	$home_url = home_url(); // Should be https://.../wp
+	// Ensure endpoint starts with /
+	$endpoint = '/' . ltrim( $endpoint, '/' );
+	// Construct the base plain permalink URL
+	$correct_url = rtrim( $home_url, '/' ) . '/?rest_route=' . $endpoint;
+
+	// Append original query parameters (if any, besides rest_route)
+	if ( !empty( $query_str ) ) {
+		parse_str( $query_str, $query_params );
+		unset( $query_params['rest_route'] ); // Ensure no leftover rest_route
+		if ( ! empty( $query_params ) ) {
+			// Check if $correct_url already has '?' (it should)
+			$correct_url .= '&' . http_build_query( $query_params );
+		}
+	}
+	// Append fragment if present
+	if ( !empty( $fragment ) ) {
+		$correct_url .= '#' . $fragment;
+	}
+
+	// Use normalization helper if available
+	if ( function_exists( __NAMESPACE__ . '\\__normalize_wp_url' ) ) {
+		return __normalize_wp_url( $correct_url );
+	} else {
+		return $correct_url; // Return without full normalization as fallback
+	}
+}
+
+/**
+ * Corrects generated REST API URL when plain permalinks are active but WordPress
+ * incorrectly generates a pretty-permalink-style path. Forces the URL
+ * back to the expected ?rest_route= format using helpers.
+ *
+ * @since 1.2.3 // TODO: Update version before release
+ * @param string $url The potentially incorrect REST URL generated by WP.
+ * @return string The corrected REST URL in plain permalink format.
+ */
+function filter_force_plain_rest_url_format( string $url ) : string {
+	$parsed_url = parse_url($url);
+
+	// Check if it looks like a pretty permalink URL (has /wp-json/ in path)
+	// AND lacks the ?rest_route= query parameter.
+	$has_wp_json_path = isset( $parsed_url['path'] ) && strpos( $parsed_url['path'], '/wp-json/' ) !== false;
+	$has_rest_route_query = isset( $parsed_url['query'] ) && strpos( $parsed_url['query'], 'rest_route=' ) !== false;
+
+	if ( $has_wp_json_path && ! $has_rest_route_query ) {
+		// It's using a pretty path format when it shouldn't be.
+		$endpoint = __extract_rest_endpoint( $parsed_url['path'] );
+		return __build_plain_rest_url( $endpoint, $parsed_url['query'] ?? null, $parsed_url['fragment'] ?? null );
+	}
+
+	// If the URL didn't match the problematic pattern, return it normalized.
+    return __normalize_wp_url($url);
+}
+
+/**
+ * Handles incoming requests using a pretty REST API path format when plain
+ * permalinks are active. It sets the correct 'rest_route' query variable
+ * internally instead of performing an external redirect.
+ *
+ * @since 1.2.3
+ * @param \WP $wp The WP object, passed by reference.
+ */
+function handle_pretty_rest_request_on_plain_permalinks( \WP &$wp ) {
+	// Only run if it's not an admin request. Permalink structure checked by the hook caller.
+	if ( is_admin() ) {
+		return;
+	}
+
+	// Use REQUEST_URI as it's more reliable for the raw request path before WP parsing.
+	$request_uri = $_SERVER['REQUEST_URI'] ?? '';
+	// Get the path part before any query string.
+	$request_path = strtok($request_uri, '?');
+
+	// Define the pretty permalink base path we expect if pretty permalinks *were* active.
+	$home_url_path = rtrim( parse_url( home_url(), PHP_URL_PATH ) ?: '', '/' ); // e.g., /wp
+	$pretty_rest_path_base = $home_url_path . '/wp-json/'; // e.g., /wp/wp-json/
+
+	// Check if the actual request path starts with this pretty base.
+	if ( strpos( $request_path, $pretty_rest_path_base ) === 0 ) {
+		// Extract the endpoint part *after* the base.
+		$endpoint = substr( $request_path, strlen( $pretty_rest_path_base ) );
+		// Ensure endpoint starts with a slash, default to base if empty.
+		$endpoint = '/' . ltrim($endpoint, '/');
+		// If the result is just '/', set it back to empty string for root endpoint ?rest_route=/
+		$endpoint = ($endpoint === '/') ? '' : $endpoint;
+
+		// Check if rest_route is already set (e.g., from query string), if so, don't overwrite.
+		// This prevents conflicts if someone manually crafts a URL like /wp/wp-json/posts?rest_route=/users
+		if ( ! isset( $wp->query_vars['rest_route'] ) ) {
+			// Directly set the query variable for the REST API.
+			$wp->query_vars['rest_route'] = $endpoint;
+
+			// Optional: Unset other query vars WP might have incorrectly parsed.
+			// unset($wp->query_vars['pagename'], $wp->query_vars['error']);
+		}
+		// No redirect, no exit. Let WP continue processing with the modified query vars.
+	}
+}
+
+// Only add the REST URL *generation* fix and the request handler if plain permalinks are enabled.
+if ( ! get_option('permalink_structure') ) {
+	add_filter('rest_url', __NAMESPACE__ . '\\filter_force_plain_rest_url_format', 10, 1);
+	// Hook the request handling logic to parse_request. Pass the $wp object by reference.
+	add_action('parse_request', __NAMESPACE__ . '\\handle_pretty_rest_request_on_plain_permalinks', 1, 1);
+}