initial

includes/Events/RsvEventDispatcher.php

@@ -0,0 +1,39 @@
+<?php
+
+interface RsvEventBusInterface {
+    public function dispatch(object $event): void;
+    public function listen(string $event_class, callable $listener): void;
+}
+
+class RsvWordPressEventBus implements RsvEventBusInterface {
+    public function dispatch(object $event): void {
+        do_action(get_class($event), $event);
+    }
+
+    public function listen(string $event_class, callable $listener): void {
+        add_action($event_class, $listener);
+    }
+}
+
+class RsvEventDispatcher {
+    private static ?RsvEventBusInterface $bus = null;
+
+    public static function init(RsvEventBusInterface $bus): void {
+        self::$bus = $bus;
+    }
+
+    private static function bus(): RsvEventBusInterface {
+        // Fall back to the WordPress bus if init() was never called, so a stray
+        // dispatch/listen during early bootstrap can't fatal on an uninitialised
+        // typed property.
+        return self::$bus ??= new RsvWordPressEventBus();
+    }
+
+    public static function dispatch(object $event): void {
+        self::bus()->dispatch($event);
+    }
+
+    public static function listen(string $event_class, callable $listener): void {
+        self::bus()->listen($event_class, $listener);
+    }
+}