function freezeProp(obj, prop) {
  Object.defineProperty(obj, prop, {configurable: false, writable: false});
}

function guidGenerator() {
  var S4 = function() {
    return (((1+Math.random())*0x10000)|0).toString(16).substring(1);
  };
  return (S4()+S4()+"-"+S4()+"-"+S4()+"-"+S4()+"-"+S4()+S4()+S4());
}

class Thread {
  constructor() {
    this.id = guidGenerator();
    freezeProp(this, "id");
    this.stopped = false;
    this.running = false;
    this.runOnce = null;
    this.runConstantly = null;
    this.context = {};
  }

  set(runOnce, runConstantly) {
    this.runOnce = () => runOnce.apply(this.context);
    this.runConstantly = () => runConstantly.apply(this.context);
  }

  start() {
    if (!this.running) {
      const self = this.context;
  
      const delay = (ms) => new Promise(resolve => setTimeout(resolve, ms));
      self.delay = delay;
      self.id = this.id;
      self.dis = {};
      freezeProp(self, "id");
      freezeProp(self, "delay");
  
      const runConstantlyFunc = async () => {
        while (!this.stopped) {
          await this.runConstantly.apply(this.context);
          for (var member in self.dis) delete self.dis[member];
        }
      };
  
      if (this.runOnce != null) {
        (async () => {
          await this.runOnce.apply(this.context);
          if (this.runConstantly != null) {
            runConstantlyFunc();
          }
        })();
      } else if (this.runConstantly != null) {
        runConstantlyFunc();
      }
    } else {
      this.stopped = false;
    }
  }

  stop() {
    this.stopped = true;
  }
}