<?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);
    }
}