// src/hooks/useDebounce.ts
import { onUnmounted, Ref } from 'vue';
import { useState } from './useState';
import { useEffect } from './useEffect';

export interface UseDebounceOptions {
  delay?: number;
  immediate?: boolean;
  maxWait?: number;
}

export function useDebounce<T>(source: Ref<T>, options: number | UseDebounceOptions = {}) {
  const config = typeof options === 'number' ? { delay: options } : options;
  const { delay = 300, immediate = false, maxWait } = config;

  const [debouncedValue, setDebouncedValue] = useState<T>(source.value as T);
  const [isPending, setIsPending] = useState(false);

  let timer: any = null;
  let maxWaitTimer: any = null;
  let isFirstCall = true; // 标记是否为首次调用，用于 immediate 模式

  // 清理
  const clearTimers = () => {
    if (timer) {
      clearTimeout(timer);
      timer = null;
    }
    if (maxWaitTimer) {
      clearTimeout(maxWaitTimer);
      maxWaitTimer = null;
    }
  };

  // 更新
  const updateValue = () => {
    setDebouncedValue(source.value);
    setIsPending(false);
    clearTimers();
    // 安静期结束后重置 isFirstCall，使下次触发能立即执行（immediate 模式）
    isFirstCall = true;
  };

  useEffect(() => {
    setIsPending(true);

    // 处理 maxWait
    if (maxWait && !maxWaitTimer) {
      maxWaitTimer = setTimeout(() => {
        updateValue();
      }, maxWait);
    }

    // 处理 delay
    if (timer) clearTimeout(timer);

    if (immediate && isFirstCall) {
      isFirstCall = false;
      updateValue();
    } else {
      timer = setTimeout(() => {
        updateValue();
      }, delay);
    }

    return clearTimers;
  }, [source]);

  // 卸载
  onUnmounted(() => {
    clearTimers();
  });

  return {
    debouncedValue,
    isPending,
    refresh: updateValue,
    cancel: clearTimers,
  };
}