Use WP Autoloader class

activitypub.php

@@ -27,9 +27,13 @@
 \define( 'ACTIVITYPUB_PLUGIN_FILE', ACTIVITYPUB_PLUGIN_DIR . basename( __FILE__ ) );
 \define( 'ACTIVITYPUB_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
 
+require_once __DIR__ . '/includes/class-autoloader.php';
 require_once __DIR__ . '/includes/compat.php';
 require_once __DIR__ . '/includes/functions.php';
 require_once __DIR__ . '/includes/constants.php';
+require_once __DIR__ . '/integration/load.php';
+
+Autoloader::register_path( __NAMESPACE__, __DIR__ . '/includes' );
 
 /**
  * Initialize REST routes.
@@ -81,6 +85,22 @@ function plugin_init() {
 }
 \add_action( 'plugins_loaded', __NAMESPACE__ . '\plugin_init' );
 
+/**
+ * Add plugin settings link.
+ *
+ * @param array $actions The current actions.
+ */
+function plugin_settings_link( $actions ) {
+	$settings_link   = array();
+	$settings_link[] = \sprintf(
+		'<a href="%1s">%2s</a>',
+		\menu_page_url( 'activitypub', false ),
+		\__( 'Settings', 'activitypub' )
+	);
+
+	return \array_merge( $settings_link, $actions );
+}
+\add_filter( 'plugin_action_links_' . ACTIVITYPUB_PLUGIN_BASENAME, __NAMESPACE__ . '\plugin_settings_link' );
 
 /**
  * Class Autoloader.
@@ -144,8 +164,6 @@ function ( $full_class ) {
 	)
 );
 
-// Load integrations.
-require_once __DIR__ . '/integration/load.php';
 
 /**
  * `get_plugin_data` wrapper.

includes/class-autoloader.php

@@ -0,0 +1,106 @@
+<?php
+/**
+ * Autoloader for Activitypub.
+ *
+ * @package Activitypub
+ */
+
+namespace Activitypub;
+
+/**
+ * An Autoloader that respects WordPress's filename standards.
+ */
+class Autoloader {
+
+	/**
+	 * Namespace separator.
+	 */
+	const NS_SEPARATOR = '\\';
+
+	/**
+	 * The prefix to compare classes against.
+	 *
+	 * @var string
+	 * @access protected
+	 */
+	protected $prefix;
+
+	/**
+	 * Length of the prefix string.
+	 *
+	 * @var int
+	 * @access protected
+	 */
+	protected $prefix_length;
+
+	/**
+	 * Path to the file to be loaded.
+	 *
+	 * @var string
+	 * @access protected
+	 */
+	protected $path;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param string $prefix Namespace prefix all classes have in common.
+	 * @param string $path   Path to the files to be loaded.
+	 */
+	public function __construct( $prefix, $path ) {
+		$this->prefix        = $prefix;
+		$this->prefix_length = strlen( $prefix );
+		$this->path          = rtrim( $path . '/' );
+	}
+
+	/**
+	 * Registers Autoloader's autoload function.
+	 *
+	 * @throws \Exception When autoload_function cannot be registered.
+	 *
+	 * @param string $prefix Namespace prefix all classes have in common.
+	 * @param string $path   Path to the files to be loaded.
+	 */
+	public static function register_path( $prefix, $path ) {
+		$loader = new Autoloader( $prefix, $path );
+		spl_autoload_register( array( $loader, 'load' ) );
+	}
+
+	/**
+	 * Loads a class if its namespace starts with `$this->prefix`.
+	 *
+	 * @param string $class_name The class to be loaded.
+	 */
+	public function load( $class_name ) {
+		if ( strpos( $class_name, $this->prefix . self::NS_SEPARATOR ) !== 0 ) {
+			return;
+		}
+
+		// Strip prefix from the start (ala PSR-4).
+		$class_name = substr( $class_name, $this->prefix_length + 1 );
+		$class_name = strtolower( $class_name );
+		$dir        = '';
+
+		$last_ns_pos = strripos( $class_name, self::NS_SEPARATOR );
+		if ( false !== $last_ns_pos ) {
+			$namespace  = substr( $class_name, 0, $last_ns_pos );
+			$namespace  = str_replace( '_', '-', $namespace );
+			$class_name = substr( $class_name, $last_ns_pos + 1 );
+			$dir        = str_replace( self::NS_SEPARATOR, DIRECTORY_SEPARATOR, $namespace ) . DIRECTORY_SEPARATOR;
+		}
+
+		$path = $this->path . $dir . 'class-' . str_replace( '_', '-', $class_name ) . '.php';
+
+		if ( ! file_exists( $path ) ) {
+			$path = $this->path . $dir . 'interface-' . str_replace( '_', '-', $class_name ) . '.php';
+		}
+
+		if ( ! file_exists( $path ) ) {
+			$path = $this->path . $dir . 'trait-' . str_replace( '_', '-', $class_name ) . '.php';
+		}
+
+		if ( file_exists( $path ) ) {
+			require_once $path;
+		}
+	}
+}