/**
 * Returns a function, that, when invoked, will only be triggered at most once
 * during a given window of time. Normally, the throttled function will run
 * as much as it can, without ever going more than once per `wait` duration;
 * but if you'd like to disable the execution on the leading edge, pass
 * @param func
 * @param wait
 * @param options
 * @returns
 */
// `{leading: false}`. To disable execution on the trailing edge, ditto.
export function throttle(func, wait, options?) {
  var context, args, result
  var timeout = null
  var previous = 0
  if (!options) options = {}
  var later = function () {
    previous = options.leading === false ? 0 : Date.now()
    timeout = null
    result = func.apply(context, args)
    if (!timeout) context = args = null
  }
  return function () {
    var now = Date.now()
    if (!previous && options.leading === false) previous = now
    var remaining = wait - (now - previous)
    context = null
    args = arguments
    if (remaining <= 0 || remaining > wait) {
      if (timeout) {
        clearTimeout(timeout)
        timeout = null
      }
      previous = now
      result = func.apply(context, args)
      if (!timeout) context = args = null
    } else if (!timeout && options.trailing !== false) {
      timeout = setTimeout(later, remaining)
    }
    return result
  }
}