/**
 * Debounce a function
 * @param  {any}     func      function to executoe
 * @param  {number}  wait      wait duration
 * @param  {boolean} immediate wait or immediate executue
 */
export function debounce(func: any, wait: number, immediate?: boolean) {
  let timeout;
  let args;
  let context;
  let timestamp;
  let result;

  return function() {
    context = this;
    args = arguments;
    timestamp = new Date();

    function later() {
      const last = +new Date() - timestamp;

      if (last < wait) {
        timeout = setTimeout(later, wait - last);
      } else {
        timeout = null;
        if (!immediate) {
          result = func.apply(context, args);
        }
      }
    }

    let callNow = immediate && !timeout;
    if (!timeout) {
      timeout = setTimeout(later, wait);
    }

    if (callNow) {
      result = func.apply(context, args);
    }

    return result;
  };
}

/**
 * Debounce decorator
 *
 *  class MyClass {
 *    debounceable(10)
 *    myFn() { ... }
 *  }
 */
export function debounceable(duration: number, immediate?: boolean) {
  return function innerDecorator (target, key, descriptor) {
    return {
      configurable: true,
      enumerable: descriptor.enumerable,
      get: function getter () {

        Object.defineProperty(this, key, {
          configurable: true,
          enumerable: descriptor.enumerable,
          value: debounce(descriptor.value, duration, immediate)
        });

        return this[key];
      }
    };
  };
}