/**
 * CallTimer wraps Node's setTimeout/clearTimeout to allow session cancellations.
 */
export class CallTimer {
  /**
   * @param {number} durationMs 
   * @param {function} onExpiry 
   */
  constructor(durationMs, onExpiry) {
    this.timer = setTimeout(onExpiry, durationMs);
  }

  /**
   * Cancels the active timer.
   */
  stop() {
    if (this.timer) {
      clearTimeout(this.timer);
      this.timer = null;
    }
  }
}

/**
 * Starts a session timeout timer.
 * @param {number} durationMs 
 * @param {function} onExpiry 
 * @returns {CallTimer}
 */
export function startTimer(durationMs, onExpiry) {
  return new CallTimer(durationMs, onExpiry);
}