import { ref } from 'vue';

/**
 * 节流函数封装
 * @param fn 需要节流的函数
 * @param delay 节流间隔时间(ms)，默认 500
 * @returns 返回节流后的函数，连续调用时只会在每个 delay 周期内执行一次
 */
export function useThrottleFn<T extends (...args: any[]) => any>(
  fn: T,
  delay: number = 500,
): T & { cancel: () => void } {
  const lastTime = ref<number>(0);
  let timer: any = null;

  const throttled = function (this: any, ...args: any[]) {
    const now = Date.now();
    const remaining = delay - (now - lastTime.value);

    if (remaining <= 0) {
      // 冷却时间已过，立即执行
      if (timer) {
        clearTimeout(timer);
        timer = null;
      }
      lastTime.value = now;
      fn.apply(this, args);
    } else if (!timer) {
      // 冷却时间未过，延后执行
      timer = setTimeout(() => {
        lastTime.value = Date.now();
        timer = null;
        fn.apply(this, args);
      }, remaining);
    }
  } as T & { cancel: () => void };

  throttled.cancel = () => {
    if (timer) {
      clearTimeout(timer);
      timer = null;
    }
  };

  return throttled;
}