import 'dart:async';

import 'package:flutter/widgets.dart';

ValueChanged debounceValueChanged(ValueChanged fn, [int t = 500]) {
  Timer _debounce;
  return (value) {
    // 还在时间之内，抛弃上一次
    if (_debounce?.isActive ?? false) _debounce.cancel();

    _debounce = Timer(Duration(milliseconds: t), () {
      fn(value);
    });
  };
}


Function debounce(
  Function func, [
  Duration delay = const Duration(milliseconds: 2000),
]) {
  Timer timer;
  Function target = () {
    if (timer?.isActive ?? false) {
      timer?.cancel();
    }
    timer = Timer(delay, () {
      func?.call();
    });
  };
  return target;
}

Function throttle(
  Future Function() func,
) {
  if (func == null) {
    return func;
  }
  bool enable = true;
  Function target = () {
    if (enable == true) {
      enable = false;
      func().then((_) {
        enable = true;
      });
    }
  };
  return target;
}