import { nextTick, onBeforeUnmount, watch } from 'vue';
import { applyWrapStyles, findModalWrap, queryModalWrap } from '../lib/modalWrap';

/**
 * 弹框拖拽与居中：拖标题栏移动窗口，缩放环境下把鼠标视口坐标换算回布局坐标。
 *
 * 拖拽状态刻意用普通变量（非响应式），避免 mousemove 触发渲染；
 * modal-wrap 的定位样式统一走 lib/modalWrap，与面板侧的全屏逻辑共用同一套选择器。
 */
export interface ChatDragDeps {
  getIsFullscreen: () => boolean;
  getVisible: () => boolean | undefined;
}

export const useChatDrag = (deps: ChatDragDeps) => {
  // 拖拽相关（使用普通变量避免 mousemove 触发 Vue 响应式导致卡顿）
  let isDragging = false;
  let dragStartX = 0;
  let dragStartY = 0;
  let modalStartLeft = 0;
  let modalStartTop = 0;
  // 容器 scale 缩放比（视觉尺寸/布局尺寸），用于把鼠标视口坐标换算回布局坐标
  let dragScaleX = 1;
  let dragScaleY = 1;
  let draggedEl: HTMLElement | null = null;

  const centerModal = () => {
    nextTick(() => {
      applyWrapStyles(deps.getIsFullscreen());
      draggedEl = null;
    });
  };

  const onDragStart = (e: MouseEvent) => {
    if (deps.getIsFullscreen()) return;
    draggedEl = findModalWrap(e.target as HTMLElement) || queryModalWrap();
    if (!draggedEl) return;

    // 记录容器缩放比，并把鼠标/弹框的视口坐标换算回布局坐标，避免不同分辨率下拖拽位移失真
    const rect = draggedEl.getBoundingClientRect();
    dragScaleX = draggedEl.offsetWidth ? rect.width / draggedEl.offsetWidth : 1;
    dragScaleY = draggedEl.offsetHeight ? rect.height / draggedEl.offsetHeight : 1;

    isDragging = true;
    dragStartX = e.clientX;
    dragStartY = e.clientY;
    modalStartLeft = rect.left / dragScaleX;
    modalStartTop = rect.top / dragScaleY;

    draggedEl.style.position = 'fixed';
    draggedEl.style.left = `${modalStartLeft}px`;
    draggedEl.style.top = `${modalStartTop}px`;
    draggedEl.style.margin = '0';
    draggedEl.style.transform = 'none';

    document.addEventListener('mousemove', onDragMove);
    document.addEventListener('mouseup', onDragEnd);
  };

  const onDragMove = (e: MouseEvent) => {
    if (!isDragging || !draggedEl) return;
    draggedEl.style.left = `${modalStartLeft + (e.clientX - dragStartX) / dragScaleX}px`;
    draggedEl.style.top = `${modalStartTop + (e.clientY - dragStartY) / dragScaleY}px`;
  };

  const onDragEnd = () => {
    isDragging = false;
    document.removeEventListener('mousemove', onDragMove);
    document.removeEventListener('mouseup', onDragEnd);
  };

  watch(deps.getVisible, (newVisible) => {
    if (newVisible) {
      centerModal();
    }
  });

  onBeforeUnmount(() => {
    document.removeEventListener('mousemove', onDragMove);
    document.removeEventListener('mouseup', onDragEnd);
  });

  return { onDragStart, centerModal };
};