/* 
 * async Event Emitter
 *  
 * // Example usage
 * const emitter = new AsyncEmitter();
 * 
 * // Register some async listeners
 * emitter.on("data", async (msg) => {
 *   console.log("Listener 1 starting...");
 *   await new Promise((r) => setTimeout(r, 1000));
 *   console.log("Listener 1 done:", msg);
 * });
 * 
 * emitter.on("data", async (msg) => {
 *   console.log("Listener 2 starting...");
 *   await new Promise((r) => setTimeout(r, 500));
 *   console.log("Listener 2 done:", msg);
 * });
 * 
 * (async () => {
 *   console.log("Emitting...");
 *   await emitter.emit("data", "Hello async world!");
 *   console.log("All listeners finished.");
 * })();
 */ 

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

  on(event, listener) {
    if (!this.listeners.has(event)) this.listeners.set(event, []);
    this.listeners.get(event).push( listener );
  }

  async emit(event, ...args) {
    const listeners = this.listeners.get(event) || [];
    if( document.location.hostname == 'localhost' ) console.info(`emit(${event})`)
    for (const fn of listeners) {
      await fn(...args); // <-- Waits for each listener to finish
    }
  }
}

export {AsyncEmitter}