import { ref, watch, onUnmounted, unref, type Ref, onMounted } from 'vue';
import { useScroll, type UseScrollReturn } from '@vueuse/core';
import gsap from 'gsap';
const ticker = gsap.ticker;

export interface AutoScrollOptions {
  /** 延迟（刻），滚动启动、反转、用户交互后的重新开始的延迟 */
  delay?: number;
  /** 滚动到底部后是否回滚（否则是回到顶部重新滚动） */
  rollBack?: boolean;
  /** 每一刻滚动的像素数 */
  step?: number;
  /** 是否自动开始 */
  autoStart?: boolean;
  /** 滚动方向 */
  direction?: 'x' | 'y';
}

export interface AutoScrollReturn {
  /** 开始/恢复滚动 */
  start: () => void;
  /** 暂停滚动 */
  pause: () => void;
  /** 重置到初始状态 */
  reset: () => void;
  /** 反转滚动 */
  reverse: () => void;
  /** 恢复滚动 */
  resume: () => void;
}

export function useAutoScroll(container: Ref<HTMLElement | null> | HTMLElement | null, options: AutoScrollOptions = {}): AutoScrollReturn {
  const {
    delay = 300, // 默认60帧（约1秒）
    rollBack = false,
    step = 1,
    autoStart = true,
    direction = 'y',
  } = options;

  let cleanupListeners: (() => void) | null = null;

  // 状态管理
  const isActive = ref(false);
  const currentDirection = ref(1); // 1: 正向, -1: 反向
  const delayFrames = ref(0);

  // 使用 VueUse 的 useScroll
  const { arrivedState, x, y } = useScroll(container, {
    behavior: 'smooth',
  }) as UseScrollReturn;

  // 检查是否到达边界
  const checkBoundary = (): boolean => {
    if (direction === 'y') {
      return currentDirection.value > 0 ? arrivedState.bottom : arrivedState.top;
    } else {
      return currentDirection.value > 0 ? arrivedState.right : arrivedState.left;
    }
  };

  // 执行滚动
  const performScroll = () => {
    if (!isActive.value) return;
    if (delayFrames.value > 0) {
      delayFrames.value--;
      return;
    }

    // 检查边界
    if (checkBoundary()) {
      if (rollBack) {
        // 回滚模式：反转方向
        reverse();
      } else {
        // 循环模式：回到开始位置
        reset();
      }
      return;
    }

    // 执行滚动
    if (direction === 'y') {
      y.value += step * currentDirection.value;
    } else {
      x.value += step * currentDirection.value;
    }
  };

  // 开始/恢复滚动
  const start = () => {
    if (!isActive.value) {
      ticker.remove(performScroll);
      ticker.add(performScroll);
      isActive.value = true;
      delayFrames.value = delay;
    }
  };

  // 暂停滚动
  const pause = () => {
    delayFrames.value = Number.MAX_SAFE_INTEGER;
  };

  // 重置到初始状态
  const reset = () => {
    if (direction === 'y') {
      y.value = 0;
    } else {
      x.value = 0;
    }
    currentDirection.value = 1;
    delayFrames.value = delay;
  };

  // 反转滚动方向
  const reverse = () => {
    currentDirection.value *= -1;
    delayFrames.value = delay;
  };

  const resume = () => {
    delayFrames.value = delay;
  };

  // 监听用户交互事件
  const setupUserInteractionListeners = (el: HTMLElement) => {
    // 鼠标滚轮事件
    const handleWheel = () => {
      resume();
    };

    // 鼠标按下事件（用于拖动滚动条）
    const handleMouseDown = () => {
      pause();
    };

    // 鼠标抬起事件
    const handleMouseUp = () => {
      resume();
    };

    // 触摸事件
    const handleTouchStart = () => {
      pause();
    };

    const handleTouchEnd = () => {
      resume();
    };

    // 键盘事件（PageUp/PageDown/方向键）
    const handleKeyDown = (e: KeyboardEvent) => {
      const scrollKeys = ['PageUp', 'PageDown', 'ArrowUp', 'ArrowDown', 'ArrowLeft', 'ArrowRight', 'Space'];
      if (scrollKeys.includes(e.key)) {
        pause();
      }
    };

    const handleKeyUp = () => {
      resume();
    };

    // 添加事件监听
    el.addEventListener('wheel', handleWheel, { passive: true });
    el.addEventListener('mousedown', handleMouseDown);
    el.addEventListener('mouseup', handleMouseUp);
    el.addEventListener('touchstart', handleTouchStart, { passive: true });
    el.addEventListener('touchend', handleTouchEnd);
    el.addEventListener('keydown', handleKeyDown);
    el.addEventListener('keyup', handleKeyUp);

    // 返回清理函数
    return () => {
      el.removeEventListener('wheel', handleWheel);
      el.removeEventListener('mousedown', handleMouseDown);
      el.removeEventListener('mouseup', handleMouseUp);
      el.removeEventListener('touchstart', handleTouchStart);
      el.removeEventListener('touchend', handleTouchEnd);
      el.removeEventListener('keydown', handleKeyDown);
      el.removeEventListener('keyup', handleKeyUp);
    };
  };

  // 监听容器变化
  watch(
    () => unref(container),
    (newContainer) => {
      if (cleanupListeners) {
        cleanupListeners();
        cleanupListeners = null;
      }
      if (newContainer) {
        cleanupListeners = setupUserInteractionListeners(newContainer);
        // 容器变化时重置状态
        reset();
      }
    }
  );

  onMounted(() => {
    // 自动开始
    if (autoStart) {
      start();
    }
  });

  // 清理
  onUnmounted(() => {
    ticker.remove(performScroll);
  });

  return {
    start,
    pause,
    reset,
    reverse,
    resume,
  };
}