export class EventBus {
    constructor() {
        this.listeners = new Map();
    }

    on(eventName, listener) {
        if (!this.listeners.has(eventName)) {
            this.listeners.set(eventName, new Set());
        }

        const listeners = this.listeners.get(eventName);
        listeners.add(listener);

        return () => {
            listeners.delete(listener);
            if (listeners.size === 0) {
                this.listeners.delete(eventName);
            }
        };
    }

    emit(eventName, payload) {
        const listeners = this.listeners.get(eventName);
        if (!listeners) {
            return;
        }

        for (const listener of listeners) {
            listener(payload);
        }
    }
}