Merge pull request 'Refactoring: each event plugin is now represented by the implementation of a Event_Plugin base class.' (#24) from class_plugin_adapter into main

Reviewed-on: Event-Federation/wordpress-activitypub-event-extensions#24

activitypub-event-extensions.php

@@ -8,8 +8,10 @@
  * Author URI:   https://graz.social/@linos
  * Text Domain:  activitypub-event-extensions
  * License:      AGPL-3.0-or-later
+ * License URI:  https://www.gnu.org/licenses/agpl-3.0.de.html
+ * Requires PHP: 8.1
  *
- * ActivityPub tested up to: 3.1.0
+ * ActivityPub plugin tested up to: 3.2.2
  *
  * @package activitypub-event-extensions
  * @license AGPL-3.0-or-later

includes/activitypub/transformer/class-events-manager.php

@@ -23,7 +23,7 @@ if ( ! defined( 'ABSPATH' ) ) {
  *
  * @since 1.0.0
  */
-class Events_Manager extends Event_Transformer {
+final class Events_Manager extends Event_Transformer {
 
 	/**
 	 * Holds the EM_Event object.

includes/activitypub/transformer/class-gatherpress.php

@@ -23,7 +23,7 @@ if ( ! defined( 'ABSPATH' ) ) {
  *
  * @since 1.0.0
  */
-class GatherPress extends Event {
+final class GatherPress extends Event {
 
 	/**
 	 * The target ActivityPub Event object of the transformer.

includes/activitypub/transformer/class-the-events-calendar.php

@@ -22,7 +22,7 @@ use WP_Post;
  *
  * @since 1.0.0
  */
-class The_Events_Calendar extends Event {
+final class The_Events_Calendar extends Event {
 
 	/**
 	 * The Tribe Event object.
@@ -38,9 +38,10 @@ class The_Events_Calendar extends Event {
 	 * has a lot of useful functions, we make use of our getter functions.
 	 *
 	 * @param WP_Post $wp_object The WordPress object.
+	 * @param string  $wp_taxonomy The taxonomy slug of the event post type.
 	 */
-	public function __construct( $wp_object ) {
+	public function __construct( $wp_object, $wp_taxonomy ) {
-		parent::__construct( $wp_object );
+		parent::__construct( $wp_object, $wp_taxonomy );
 		$this->tribe_event = \tribe_get_event( $wp_object );
 	}
 

includes/activitypub/transformer/class-vs-event-list.php

@@ -26,7 +26,7 @@ if ( ! defined( 'ABSPATH' ) ) {
  *
  * @since 1.0.0
  */
-class VS_Event_List extends Event_Transformer {
+final class VS_Event_List extends Event_Transformer {
 
 	/**
 	 * The target transformer ActivityPub Event object.
@@ -44,7 +44,7 @@ class VS_Event_List extends Event_Transformer {
 	 * @access public
 	 * @return string Widget name.
 	 */
-	public function get_transformer_name() {
+	public function get_transformer_name(): string {
 		return 'activitypub-event-transformers/vs-event';
 	}
 
@@ -57,7 +57,7 @@ class VS_Event_List extends Event_Transformer {
 	 * @access public
 	 * @return string Widget title.
 	 */
-	public function get_transformer_label() {
+	public function get_transformer_label(): string {
 		return 'VS Event';
 	}
 
@@ -70,7 +70,7 @@ class VS_Event_List extends Event_Transformer {
 	 * @access public
 	 * @return array Widget categories.
 	 */
-	public static function get_supported_post_types() {
+	public static function get_supported_post_types(): string {
 		return array( 'event' );
 	}
 
@@ -81,16 +81,16 @@ class VS_Event_List extends Event_Transformer {
 	 * @since 1.0.0
 	 * @return string The Event Object-Type.
 	 */
-	protected function get_type() {
+	protected function get_type(): string {
 		return 'Event';
 	}
 
 	/**
 	 * Get the event location.
 	 *
-	 * @return array The Place.
+	 * @return Place The Place.
 	 */
-	public function get_location() {
+	public function get_location(): Place {
 		$address = get_post_meta( $this->wp_object->ID, 'event-location', true );
 		$place   = new Place();
 		$place->set_type( 'Place' );
@@ -102,7 +102,7 @@ class VS_Event_List extends Event_Transformer {
 	/**
 	 * Get the end time from the events metadata.
 	 */
-	protected function get_end_time() {
+	protected function get_end_time(): string {
 		$end_time = get_post_meta( $this->wp_object->ID, 'event-date', true );
 		return \gmdate( 'Y-m-d\TH:i:s\Z', $end_time );
 	}
@@ -110,7 +110,7 @@ class VS_Event_List extends Event_Transformer {
 	/**
 	 * Get the end time from the events metadata.
 	 */
-	protected function get_start_time() {
+	protected function get_start_time(): string {
 		$start_time = get_post_meta( $this->wp_object->ID, 'event-start-date', true );
 		return \gmdate( 'Y-m-d\TH:i:s\Z', $start_time );
 	}
@@ -118,7 +118,7 @@ class VS_Event_List extends Event_Transformer {
 	/**
 	 * Get the event link from the events metadata.
 	 */
-	private function get_event_link() {
+	private function get_event_link(): array {
 		$event_link = get_post_meta( $this->wp_object->ID, 'event-link', true );
 		if ( $event_link ) {
 			return array(

includes/admin/class-event-plugin-admin-notices.php

@@ -11,6 +11,8 @@
 
 namespace Activitypub_Event_Extensions\Admin;
 
+use Activitypub_Event_Extensions\Plugins\Event_Plugin;
+
 /**
  * Class responsible for Event Plugin related admin notices.
  *
@@ -22,14 +24,14 @@ class Event_Plugin_Admin_Notices {
 	/**
 	 * Information about the event plugin.
 	 *
-	 * @var array
+	 * @var Event_Plugin
 	 */
 	protected $event_plugin;
 
 	/**
 	 * Adds admin notices to an active supported event plugin.
 	 *
-	 * @param array $event_plugin Information about the activate event plugin.
+	 * @param Event_Plugin $event_plugin Class that has implements functions to handle a certain supported activate event plugin.
 	 */
 	public function __construct( $event_plugin ) {
 		$this->event_plugin = $event_plugin;
@@ -43,32 +45,28 @@ class Event_Plugin_Admin_Notices {
 	 *
 	 * @return bool
 	 */
-	private function event_post_type_is_not_activitypub_enabled() {
+	private function event_post_type_is_not_activitypub_enabled(): bool {
-		return ! in_array( $this->event_plugin['post_type'], get_option( 'activitypub_support_post_types', array() ), true );
+		return ! in_array( $this->event_plugin::get_post_type(), get_option( 'activitypub_support_post_types', array() ), true );
 	}
 
 	/**
 	 * Display the admin notices for the plugins.
+	 *
+	 * @return void
 	 */
-	public function admin_notice_activitypub_not_enabled_for_post_type() {
+	public function admin_notice_activitypub_not_enabled_for_post_type(): void {
-		// Get the current page.
+		if ( $this->event_plugin::is_plugin_page() ) {
-		$screen = get_current_screen();
+			$this->do_admin_notice_post_type_not_activitypub_enabled();
-		// Check if we are on a edit page for the event, or on the settings page of the event plugin.
-		$is_event_plugins_edit_page     = 'edit' === $screen->base && $this->event_plugin['post_type'] === $screen->post_type;
-		$is_event_plugins_settings_page = $this->event_plugin['settings_page_id'] === $screen->id;
-
-		if ( $is_event_plugins_edit_page || $is_event_plugins_settings_page ) {
-			$this->do_admin_notice_post_type_not_activitypub_enabled( $this->event_plugin['plugin_file'] );
 		}
 	}
 
 	/**
 	 * Print admin notice that the current post type is not enabled in the ActivityPub plugin.
 	 *
-	 * @param string $event_plugin_file The event plugin file path.
+	 * @return void
 	 */
-	private function do_admin_notice_post_type_not_activitypub_enabled( $event_plugin_file ) {
+	private function do_admin_notice_post_type_not_activitypub_enabled(): void {
-		$event_plugin_data       = get_plugin_data( WP_PLUGIN_DIR . '/' . $event_plugin_file );
+		$event_plugin_data       = get_plugin_data( WP_PLUGIN_DIR . '/' . $this->event_plugin::get_plugin_file() );
 		$activitypub_plugin_data = get_plugin_data( ACTIVITYPUB_PLUGIN_FILE );
 		$notice                  = sprintf(
 			/* translators: 1: the name of the event plugin a admin notice is shown. 2: The name of the ActivityPub plugin. */

includes/admin/class-general-admin-notices.php

@@ -84,7 +84,7 @@ class General_Admin_Notices {
 	 *
 	 * @return void
 	 */
-	public static function activitypub_plugin_not_enabled() {
+	public static function activitypub_plugin_not_enabled(): void {
 		$notice = self::get_admin_notice_activitypub_plugin_not_enabled();
 		echo '<div class="notice notice-warning"><p>' . \wp_kses( $notice, self::ALLOWED_HTML ) . '</p></div>';
 	}
@@ -94,7 +94,7 @@ class General_Admin_Notices {
 	 *
 	 * @return void
 	 */
-	public static function no_supported_event_plugin_active() {
+	public static function no_supported_event_plugin_active(): void {
 		$notice = self::get_admin_notice_no_supported_event_plugin_active();
 		echo '<div class="notice notice-warning"><p>' . \wp_kses( $notice, self::ALLOWED_HTML ) . '</p></div>';
 	}

includes/admin/class-settings-page.php

@@ -12,6 +12,7 @@
 namespace Activitypub_Event_Extensions\Admin;
 
 use Activitypub_Event_Extensions\Setup;
+use Activitypub_Event_Extensions\Plugins\Event_Plugin;
 
 // Exit if accessed directly.
 defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
@@ -59,19 +60,20 @@ class Settings_Page {
 	/**
 	 * Receive the event categories (terms) used by the event plugin.
 	 *
-	 * @param array $event_plugin Contains info about a certain event plugin.
+	 * @param Event_Plugin $event_plugin Contains info about a certain event plugin.
 	 *
 	 * @return array An array of Terms.
 	 */
 	private static function get_event_terms( $event_plugin ) {
-		if ( isset( $event_plugin['taxonomy'] ) ) {
+		$taxonomy = $event_plugin::get_taxonomy();
+		if ( $taxonomy ) {
 			$event_terms = get_terms(
 				array(
-					'taxonomy'   => $event_plugin['taxonomy'],
+					'taxonomy'   => $taxonomy,
 					'hide_empty' => true,
 				)
 			);
-			return $event_terms;
+			return ! is_wp_error( $event_terms ) ? $event_terms : array();
 		} else {
 			return array();
 		}
@@ -87,8 +89,8 @@ class Settings_Page {
 
 		$event_terms = array();
 
-		foreach ( $event_plugins as $event_plugin_name => $events_plugin_info ) {
+		foreach ( $event_plugins as $event_plugin ) {
-			$event_terms = array_merge( $event_terms, self::get_event_terms( $events_plugin_info ) );
+			$event_terms = array_merge( $event_terms, self::get_event_terms( $event_plugin ) );
 		}
 
 		$args = array(

includes/class-settings.php

@@ -26,12 +26,19 @@ defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
 class Settings {
 	const SETTINGS_SLUG = 'activitypub-event-extensions';
 
+	/**
+	 * The default ActivityPub event category.
+	 *
+	 * @var string
+	 */
 	const DEFAULT_EVENT_CATEGORY = 'MEETING';
 
 	/**
 	 * Register the settings for the ActivityPub Event Extensions plugin.
+	 *
+	 * @return void
 	 */
-	public static function register_settings() {
+	public static function register_settings(): void {
 		\register_setting(
 			'activitypub-event-extensions',
 			'activitypub_event_extensions_default_event_category',
@@ -61,7 +68,7 @@ class Settings {
 	 *
 	 * @param string $event_category The ActivityPUb event category.
 	 */
-	public static function sanitize_mapped_event_category( $event_category ) {
+	public static function sanitize_mapped_event_category( $event_category ): string {
 		return self::is_allowed_event_category( $event_category ) ? $event_category : self::DEFAULT_EVENT_CATEGORY;
 	}
 
@@ -71,8 +78,10 @@ class Settings {
 	 * Currently only the default event categories are allowed to be target of a mapping.
 	 *
 	 * @param array $event_category_mappings The settings value.
+	 *
+	 * @return array An array that contains only valid mapping pairs.
 	 */
-	public static function sanitize_event_category_mappings( $event_category_mappings ) {
+	public static function sanitize_event_category_mappings( $event_category_mappings ): array {
 		if ( empty( $event_category_mappings ) ) {
 			return array();
 		}
@@ -91,7 +100,7 @@ class Settings {
 	 *
 	 * @return bool True if allowed, false otherwise.
 	 */
-	private static function is_allowed_event_category( $event_category ) {
+	private static function is_allowed_event_category( $event_category ): bool {
 		$allowed_event_categories = Event::DEFAULT_EVENT_CATEGORIES;
 		return in_array( $event_category, $allowed_event_categories, true );
 	}

includes/class-setup.php

@@ -15,6 +15,7 @@ namespace Activitypub_Event_Extensions;
 use Activitypub_Event_Extensions\Admin\Event_Plugin_Admin_Notices;
 use Activitypub_Event_Extensions\Admin\General_Admin_Notices;
 use Activitypub_Event_Extensions\Admin\Settings_Page;
+use Activitypub_Event_Extensions\Plugins\Event_Plugin;
 
 // Exit if accessed directly.
 defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
@@ -29,34 +30,6 @@ require_once ABSPATH . 'wp-admin/includes/plugin.php';
  * @since 1.0.0
  */
 class Setup {
-	const SUPPORTED_EVENT_PLUGINS = array(
-		'events_manager'      => array(
-			'plugin_file'       => 'events-manager/events-manager.php',
-			'post_type'         => 'event',
-			'settings_page'     => 'options-general.php?page=vsel',
-			'transformer_class' => 'Events_Manager',
-		),
-		'gatherpress'         => array(
-			'plugin_file'       => 'gatherpress/gatherpress.php',
-			'post_type'         => 'gatherpress_event',
-			'transformer_class' => 'GatherPress',
-			'settings_page_id'  => 'gatherpress_general',
-		),
-		'the_events_calendar' => array(
-			'plugin_file'       => 'the-events-calendar/the-events-calendar.php',
-			'post_type'         => 'tribe_events',
-			'transformer_class' => 'Tribe',
-			'settings_page_id'  => 'tribe_general',
-		),
-		'vsel'                => array(
-			'plugin_file'       => 'very-simple-event-list/vsel.php',
-			'post_type'         => 'event',
-			'settings_page_id'  => 'settings_page_vsel',
-			'transformer_class' => 'VS_Event_List',
-			'taxonomy'          => 'event_cat',
-		),
-	);
-
 	/**
 	 * Keep the information whether the ActivityPub plugin is active.
 	 *
@@ -67,7 +40,7 @@ class Setup {
 	/**
 	 * Holds an array of the currently activated supported event plugins.
 	 *
-	 * @var array
+	 * @var Event_Plugin[]
 	 */
 	protected $active_event_plugins = array();
 
@@ -80,7 +53,7 @@ class Setup {
 	 */
 	protected function __construct() {
 		$this->activitypub_plugin_is_active = is_plugin_active( 'activitypub/activitypub.php' );
-		$this->active_event_plugins         = self::detect_supported_event_plugins();
+		$this->active_event_plugins         = self::detect_active_event_plugins();
 		$this->setup_hooks();
 	}
 
@@ -109,28 +82,46 @@ class Setup {
 		return self::$instance;
 	}
 
-	/**
-	 * Function that checks for supported activated event plugins.
-	 *
-	 * @return array List of supported event plugins as keys from the SUPPORTED_EVENT_PLUGINS const.
-	 */
-	public static function detect_supported_event_plugins(): array {
-		$active_event_plugins = array();
-		foreach ( self::SUPPORTED_EVENT_PLUGINS as $event_plugin_key => $event_plugin ) {
-			if ( \is_plugin_active( $event_plugin['plugin_file'] ) ) {
-				$active_event_plugins[ $event_plugin_key ] = $event_plugin;
-			}
-		}
-		return $active_event_plugins;
-	}
-
 	/**
 	 * Getter function for the active event plugins.
+	 *
+	 * @return Event_Plugin[]
 	 */
 	public function get_active_event_plugins() {
 		return $this->active_event_plugins;
 	}
 
+	/**
+	 * Holds all the classes for the supported event plugins.
+	 *
+	 * @var array
+	 */
+	private const EVENT_PLUGIN_CLASSES = array(
+		'\Activitypub_Event_Extensions\Plugins\Events_Manager',
+		'\Activitypub_Event_Extensions\Plugins\GatherPress',
+		'\Activitypub_Event_Extensions\Plugins\The_Events_Calendar',
+		'\Activitypub_Event_Extensions\Plugins\VS_Event_List',
+	);
+
+	/**
+	 * Function that checks for supported activated event plugins.
+	 *
+	 * @return array List of supported event plugins as keys from the SUPPORTED_EVENT_PLUGINS const.
+	 */
+	public static function detect_active_event_plugins(): array {
+		$active_event_plugins = array();
+
+		foreach ( self::EVENT_PLUGIN_CLASSES as $event_plugin_class ) {
+			if ( ! class_exists( $event_plugin_class ) || ! method_exists( $event_plugin_class, 'get_plugin_file' ) ) {
+				continue;
+			}
+			$event_plugin_file = call_user_func( array( $event_plugin_class, 'get_plugin_file' ) );
+			if ( \is_plugin_active( $event_plugin_file ) ) {
+				$active_event_plugins[] = new $event_plugin_class();
+			}
+		}
+		return $active_event_plugins;
+	}
 
 	/**
 	 * Set up hooks for various purposes.
@@ -167,8 +158,10 @@ class Setup {
 	 * Add the CSS for the admin pages.
 	 *
 	 * @param string $hook_suffix The suffix of the hook.
+	 *
+	 * @return void
 	 */
-	public static function enqueue_styles( $hook_suffix ) {
+	public static function enqueue_styles( $hook_suffix ): void {
 		if ( false !== strpos( $hook_suffix, 'activitypub-event-extensions' ) ) {
 			wp_enqueue_style(
 				'activitypub-event-extensions-admin-styles',
@@ -218,9 +211,11 @@ class Setup {
 
 		// Get the transformer for a specific event plugins event-post type.
 		foreach ( $this->active_event_plugins as $event_plugin ) {
-			if ( $wp_object->post_type === $event_plugin['post_type'] ) {
+			if ( $wp_object->post_type === $event_plugin->get_post_type() ) {
-				$transformer_class = 'Activitypub_Event_Extensions\Activitypub\Transformer\\' . $event_plugin['transformer_class'];
+				$transformer_class = $event_plugin->get_activitypub_event_transformer_class();
-				return new $transformer_class( $wp_object, $event_plugin['taxonomy'] );
+				if ( class_exists( $transformer_class ) ) {
+					return new $transformer_class( $wp_object, $event_plugin->get_taxonomy() );
+				}
 			}
 		}
 
@@ -255,7 +250,7 @@ class Setup {
 	 *
 	 * @return void
 	 */
-	public function activate() {
+	public function activate(): void {
 		// Don't allow plugin activation, when the ActivityPub plugin is not activated yet.
 		if ( ! $this->activitypub_plugin_is_active ) {
 			deactivate_plugins( plugin_basename( ACTIVITYPUB_EVENT_EXTENSIONS_PLUGIN_FILE ) );

includes/plugins/class-event-plugin.php

@@ -0,0 +1,76 @@
+<?php
+/**
+ * Interface for defining supported Event Plugins.
+ *
+ * Basic information that each supported event needs for this plugin to work.
+ *
+ * @package Activitypub_Event_Extensions
+ * @since 1.0.0
+ */
+
+namespace Activitypub_Event_Extensions\Plugins;
+
+use Activitypub_Event_Extensions\Activitypub\Transformer\Event as Event_Transformer;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+/**
+ * Interface for a supported event plugin.
+ *
+ * This interface defines which information is necessary for a supported event plugin.
+ *
+ * @since 1.0.0
+ */
+abstract class Event_Plugin {
+	/**
+	 * Returns the full plugin file.
+	 *
+	 * @return string
+	 */
+	abstract public static function get_plugin_file(): string;
+
+	/**
+	 * Returns the event post type of the plugin.
+	 *
+	 * @return string
+	 */
+	abstract public static function get_post_type(): string;
+
+	/**
+	 * Returns the taxonomy used for the plugin's event categories.
+	 *
+	 * @return string
+	 */
+	abstract public static function get_taxonomy(): string;
+
+	/**
+	 * Returns the ID of the main settings page of the plugin.
+	 *
+	 * @return string The settings page url.
+	 */
+	public static function get_settings_page(): string {
+		return '';
+	}
+
+	/**
+	 * Detects whether the current screen is a admin page of the event plugin.
+	 */
+	public static function is_plugin_page(): bool {
+		// Get the current page.
+		$screen = get_current_screen();
+
+		// Check if we are on a edit page for the event, or on the settings page of the event plugin.
+		$is_event_plugins_edit_page     = 'edit' === $screen->base && static::get_post_type() === $screen->post_type;
+		$is_event_plugins_settings_page = static::get_settings_page() === $screen->id;
+
+		return $is_event_plugins_edit_page || $is_event_plugins_settings_page;
+	}
+
+	/**
+	 * Returns the Activitypub transformer for the event plugins event post type.
+	 */
+	public static function get_activitypub_event_transformer_class(): string {
+		return str_replace( 'Plugins', 'Activitypub\Transformer', static::class );
+	}
+}

includes/plugins/class-events-manager.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * Events Manager.
+ *
+ * Defines all the necessary meta information for the Events Manager WordPress Plugin.
+ *
+ * @link    https://wordpress.org/plugins/events-manager/
+ * @package Activitypub_Event_Extensions
+ * @since   1.0.0
+ */
+
+namespace Activitypub_Event_Extensions\Plugins;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+/**
+ * Interface for a supported event plugin.
+ *
+ * This interface defines which information is necessary for a supported event plugin.
+ *
+ * @since 1.0.0
+ */
+final class Events_Manager extends Event_Plugin {
+	/**
+	 * Returns the full plugin file.
+	 *
+	 * @return string
+	 */
+	public static function get_plugin_file(): string {
+		return 'events-manager/events-manager.php';
+	}
+
+	/**
+	 * Returns the event post type of the plugin.
+	 *
+	 * @return string
+	 */
+	public static function get_post_type(): string {
+		return defined( 'EM_POST_TYPE_EVENT' ) ? constant( 'EM_POST_TYPE_EVENT' ) : 'event';
+	}
+
+	/**
+	 * Returns the ID of the main settings page of the plugin.
+	 *
+	 * @return string The settings page url.
+	 */
+	public static function get_settings_page(): string {
+		return 'wp-admin/edit.php?post_type=event&page=events-manager-options#general';
+	}
+
+	/**
+	 * Returns the taxonomy used for the plugin's event categories.
+	 *
+	 * @return string
+	 */
+	public static function get_taxonomy(): string {
+		return defined( 'EM_TAXONOMY_CATEGORY' ) ? constant( 'EM_TAXONOMY_CATEGORY' ) : 'event-categories';
+	}
+}

includes/plugins/class-gatherpress.php

@@ -0,0 +1,69 @@
+<?php
+/**
+ * GatherPress.
+ *
+ * Defines all the necessary meta information for the GatherPress plugin.
+ *
+ * @link    https://wordpress.org/plugins/gatherpress/
+ * @package Activitypub_Event_Extensions
+ * @since   1.0.0
+ */
+
+namespace Activitypub_Event_Extensions\Plugins;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+/**
+ * Interface for a supported event plugin.
+ *
+ * This interface defines which information is necessary for a supported event plugin.
+ *
+ * @since 1.0.0
+ */
+final class GatherPress extends Event_Plugin {
+	/**
+	 * Returns the full plugin file.
+	 *
+	 * @return string
+	 */
+	public static function get_plugin_file(): string {
+		return 'gatherpress/gatherpress.php';
+	}
+
+	/**
+	 * Returns the event post type of the plugin.
+	 *
+	 * @return string
+	 */
+	public static function get_post_type(): string {
+		return class_exists( '\GatherPress\Core\Event' ) ? \GatherPress\Core\Event::POST_TYPE : 'gatherpress_event';
+	}
+
+	/**
+	 * Returns the ID of the main settings page of the plugin.
+	 *
+	 * @return string The settings page url.
+	 */
+	public static function get_settings_page(): string {
+		return class_exists( '\GatherPress\Core\Utility' ) ? \GatherPress\Core\Utility::prefix_key( 'general' ) : 'gatherpress_general';
+	}
+
+	/**
+	 * Returns the ActivityPub transformer class.
+	 *
+	 * @return string
+	 */
+	public static function get_activitypub_transformer_class_name(): string {
+		return 'GatherPress';
+	}
+
+	/**
+	 * Returns the taxonomy used for the plugin's event categories.
+	 *
+	 * @return string
+	 */
+	public static function get_taxonomy(): string {
+		return class_exists( '\GatherPress\Core\Topic' ) ? \GatherPress\Core\Topic::TAXONOMY : 'gatherpress_topic';
+	}
+}

includes/plugins/class-the-events-calendar.php

@@ -0,0 +1,61 @@
+<?php
+/**
+ * The Events Calendar.
+ *
+ * Defines all the necessary meta information for the events calendar.
+ *
+ * @link    https://wordpress.org/plugins/the-events-calendar/
+ * @package Activitypub_Event_Extensions
+ * @since   1.0.0
+ */
+
+namespace Activitypub_Event_Extensions\Plugins;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+/**
+ * Interface for a supported event plugin.
+ *
+ * This interface defines which information is necessary for a supported event plugin.
+ *
+ * @since 1.0.0
+ */
+final class The_Events_Calendar extends Event_plugin {
+	/**
+	 * Returns the full plugin file.
+	 *
+	 * @return string
+	 */
+	public static function get_plugin_file(): string {
+		return 'the-events-calendar/the-events-calendar.php';
+	}
+
+	/**
+	 * Returns the event post type of the plugin.
+	 *
+	 * @return string
+	 */
+	public static function get_post_type(): string {
+		return class_exists( '\Tribe__Events__Main' ) ? \Tribe__Events__Main::POSTTYPE : 'tribe_event';
+	}
+
+	/**
+	 * Returns the ID of the main settings page of the plugin.
+	 *
+	 * @return string The settings page url.
+	 */
+	public static function get_settings_page(): string {
+		// TODO: Tribe\Events\Admin\Settings::settings_page_id.
+		return 'edit.php?post_type=tribe_events&page=tec-events-settings';
+	}
+
+	/**
+	 * Returns the taxonomy used for the plugin's event categories.
+	 *
+	 * @return string
+	 */
+	public static function get_taxonomy(): string {
+		return class_exists( '\Tribe__Events__Main' ) ? \Tribe__Events__Main::TAXONOMY : 'tribe_events_cat';
+	}
+}

includes/plugins/class-vs-event-list.php

@@ -0,0 +1,72 @@
+<?php
+/**
+ * VS Events LIst.
+ *
+ * Defines all the necessary meta information for the WordPress event plugin
+ * "Very Simple Events List".
+ *
+ * @link    https://de.wordpress.org/plugins/very-simple-event-list/
+ * @package Activitypub_Event_Extensions
+ * @since   1.0.0
+ */
+
+namespace Activitypub_Event_Extensions\Plugins;
+
+use Activitypub_Event_Extensions\Event_Plugins;
+
+// Exit if accessed directly.
+defined( 'ABSPATH' ) || exit; // @codeCoverageIgnore
+
+/**
+ * Interface for a supported event plugin.
+ *
+ * This interface defines which information is necessary for a supported event plugin.
+ *
+ * @since 1.0.0
+ */
+final class VS_Event_List extends Event_Plugin {
+	/**
+	 * Returns the full plugin file.
+	 *
+	 * @return string
+	 */
+	public static function get_plugin_file(): string {
+		return 'very-simple-event-list/vsel.php';
+	}
+
+	/**
+	 * Returns the event post type of the plugin.
+	 *
+	 * @return string
+	 */
+	public static function get_post_type(): string {
+		return 'event';
+	}
+
+	/**
+	 * Returns the ID of the main settings page of the plugin.
+	 *
+	 * @return string The settings page url.
+	 */
+	public static function get_settings_page(): string {
+		return 'settings_page_vsel';
+	}
+
+	/**
+	 * Returns the ActivityPub transformer class.
+	 *
+	 * @return string
+	 */
+	public static function get_activitypub_transformer_class_name(): string {
+		return 'VS_Event';
+	}
+
+	/**
+	 * Returns the taxonomy used for the plugin's event categories.
+	 *
+	 * @return string
+	 */
+	public static function get_taxonomy(): string {
+		return 'event_cat';
+	}
+}