export class EventEmitter {
  private handlers: Map<string, Function[]>;

  constructor() {
    this.handlers = new Map<string, Function[]>();
  }

  public on(eventName: string, handler: Function): void {
    if (!this.handlers.has(eventName)) {
      this.handlers.set(eventName, []);
    }

    this.handlers.get(eventName)?.push(handler);
  }

  public off(eventName: string, handler: Function): void {
    if (!this.handlers.has(eventName)) {
      return;
    }

    const handlers = this.handlers.get(eventName);
    const index = handlers?.indexOf(handler);

    if (index !== undefined && index !== -1) {
      handlers?.splice(index, 1);
    }
  }

  public emit(eventName: string, args: any): void {
    if (!this.handlers.has(eventName)) {
      return;
    }

    const handlers = this.handlers.get(eventName);

    handlers?.forEach((handler) => {
      handler(args);
    });
  }
}