Refactoring to properly discover from client-mu-plugins

Author: srtfisher

src/class-wp-plugin-loader.php

@@ -92,22 +92,40 @@ public function set_cache_prefix( ?string $prefix ): static {
 	 * Load the requested plugins.
 	 */
 	protected function load_plugins(): void {
-		$client_mu_plugins = is_dir( WP_CONTENT_DIR . '/client-mu-plugins' );
+		$folders = [
+			WP_CONTENT_DIR . '/plugins',
+		];
+
+		// Use the client mu-plugins directory if it exists and the constant
+		// from VIP's mu-plugins is defined.
+		if ( defined( WPCOM_VIP_CLIENT_MU_PLUGIN_DIR ) ) {
+			$folders[] = WPCOM_VIP_CLIENT_MU_PLUGIN_DIR;
+		} else {
+			// Add the mu-plugins directory if the client mu-plugins directory
+			// does not exist. We wouldn't want to attempt to load from VIP's
+			// mu-plugins directory if the client mu-plugins directory exists.
+			$folders[] = WP_CONTENT_DIR . '/mu-plugins';
+		}
 
+		// Loop through each plugin and attempt to load it.
 		foreach ( $this->plugins as $plugin ) {
-			if ( file_exists( WP_PLUGIN_DIR . "/$plugin" ) && ! is_dir( WP_PLUGIN_DIR . "/$plugin" ) ) {
-				require_once WP_PLUGIN_DIR . "/$plugin";
-
-				$this->loaded_plugins[] = trim( $plugin, '/' );
-
-				continue;
-			} elseif ( $client_mu_plugins && file_exists( WP_CONTENT_DIR . "/client-mu-plugins/$plugin" ) && ! is_dir( WP_CONTENT_DIR . "/client-mu-plugins/$plugin" ) ) {
-				$plugin = ltrim( $plugin, '/' );
+			// Loop through each possible folder and attempt to load the plugin
+			// from it.
+			foreach ( $folders as $folder ) {
+				if ( file_exists( $folder . "/$plugin" ) && ! is_dir( $folder . "/$plugin" ) ) {
+					require_once $folder . "/$plugin";
+
+					// Mark the plugin as loaded if it is in the /plugins directory.
+					if ( WP_CONTENT_DIR . '/plugins' === $folder ) {
+						$this->loaded_plugins[] = trim( $plugin, '/' );
+					}
 
-				require_once WP_CONTENT_DIR . "/client-mu-plugins/$plugin";
+					continue 2;
+				}
+			}
 
-				continue;
-			} elseif ( false === strpos( $plugin, '.php' ) ) {
+			// Attempt to locate the plugin by name if it isn't a file.
+			if ( false === strpos( $plugin, '.php' ) ) {
 				// Check the APCu cache if we have a prefix set.
 				if ( $this->cache_prefix ) {
 					$cached_plugin_path = apcu_fetch( $this->cache_prefix . $plugin );
@@ -134,41 +152,54 @@ protected function load_plugins(): void {
 					WP_PLUGIN_DIR . "/$sanitized_plugin.php",
 				];
 
-				$match = null;
+				// Include the client mu-plugins directory if it exists.
+				if ( defined( WPCOM_VIP_CLIENT_MU_PLUGIN_DIR ) ) {
+					$paths[] = WPCOM_VIP_CLIENT_MU_PLUGIN_DIR . "/$sanitized_plugin/$sanitized_plugin.php";
+					$paths[] = WPCOM_VIP_CLIENT_MU_PLUGIN_DIR . "/$sanitized_plugin/plugin.php";
+					$paths[] = WPCOM_VIP_CLIENT_MU_PLUGIN_DIR . "/$sanitized_plugin.php";
+				}
 
 				foreach ( $paths as $path ) {
 					if ( file_exists( $path ) ) {
 						require_once $path; // phpcs:ignore WordPressVIPMinimum.Files.IncludingFile.UsingVariable
 
-						$match = true;
+						// Cache the plugin path in APCu if we have a prefix set.
+						if ( $this->cache_prefix ) {
+							apcu_store( $this->cache_prefix . $plugin, $path );
+						}
 
+
+						// Mark the plugin as loaded if it is in the /plugins directory.
 						$this->loaded_plugins[] = trim( substr( $path, strlen( WP_PLUGIN_DIR ) + 1 ), '/' );
-						break;
-					}
-				}
 
-				// Bail if we found a match.
-				if ( $match ) {
-					// Cache the plugin path in APCu if we have a prefix set.
-					if ( $this->cache_prefix ) {
-						apcu_store( $this->cache_prefix . $plugin, $path );
+						continue 2;
 					}
-
-					continue;
 				}
 			}
 
-			$error_message = sprintf( 'WP Plugin Loader: Plugin %s not found.', $plugin );
+			$this->handle_missing_plugin( $plugin );
+		}
+	}
 
-			trigger_error( esc_html( $error_message ), E_USER_WARNING ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_trigger_error
+	/**
+	 * Handle a missing plugin.
+	 *
+	 * @todo Change return type to never when 8.1 is required.
+	 *
+	 * @param string $plugin The plugin name passed to the loader.
+	 * @return void
+	 */
+	protected function handle_missing_plugin( string $plugin ): void {
+		$error_message = sprintf( 'WP Plugin Loader: Plugin %s not found.', $plugin );
 
-			if ( extension_loaded( 'newrelic' ) && function_exists( 'newrelic_notice_error' ) ) {
-				newrelic_notice_error( $error_message );
-			}
+		trigger_error( esc_html( $error_message ), E_USER_WARNING ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_trigger_error
 
-			// Bye bye!
-			die( esc_html( $error_message ) );
+		if ( extension_loaded( 'newrelic' ) && function_exists( 'newrelic_notice_error' ) ) {
+			newrelic_notice_error( $error_message );
 		}
+
+		// Bye bye!
+		die( esc_html( $error_message ) );
 	}
 
 	/**

stubs/constants.stub

@@ -1,3 +1,4 @@
 <?php
 define( 'WP_CONTENT_DIR', 'wp-content' );
 define( 'WP_PLUGIN_DIR', 'wp-content/plugins' );
+define( 'WPCOM_VIP_CLIENT_MU_PLUGIN_DIR', 'wp-content/client-mu-plugins' );