common.ts

interface IEvent<T> {
    on(handler: { (data?: T): void }) : void;
    off(handler: { (data?: T): void }) : void;
}

class EventHandler<T> implements IEvent<T> {
    private handlers: { (data?: T): void; }[] = [];

    public on(handler: { (data?: T): void }) {
        this.handlers.push(handler);
    }

    public off(handler: { (data?: T): void }) {
        this.handlers = this.handlers.filter(h => h !== handler);
    }

    public trigger(data?: T) {
        this.handlers.slice(0).forEach(h => h(data));
    }
}

class Message {
  public payload: string;
  public bytes: ArrayBuffer;
  public topic: string;
  public qos: number;
  constructor(mqttMessage: any){
    this.payload = mqttMessage.payloadString || '';
    this.bytes = mqttMessage.payloadBytes || null;
    this.topic = mqttMessage.destinationName || '';
    this.qos = mqttMessage.qos || 0;
  }
}

let guid = () => {
  function s4() {
    return Math.floor((1 + Math.random()) * 0x10000)
      .toString(16)
      .substring(1);
  }
  return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
    s4() + '-' + s4() + s4() + s4();
}

export { IEvent, EventHandler, guid, Message };