import React, { useCallback, useState, useEffect, useRef } from 'react'
import { useTabStore } from '../../stores/tabStore'
import { getFileName } from '../../lib/fileUtils'
import { Close, Plus } from '../Icons'

interface ContextMenuState {
  visible: boolean
  x: number
  y: number
  tabId: string
}

export function TabBar() {
  const tabs = useTabStore(s => s.tabs)
  const activeTabId = useTabStore(s => s.activeTabId)
  const switchToTab = useTabStore(s => s.switchToTab)
  const closeTab = useTabStore(s => s.closeTab)
  const createTab = useTabStore(s => s.createTab)
  const closeOtherTabs = useTabStore(s => s.closeOtherTabs)
  const closeAllTabs = useTabStore(s => s.closeAllTabs)
  const closeTabsToRight = useTabStore(s => s.closeTabsToRight)

  const tabListRef = useRef<HTMLDivElement>(null)
  const [menu, setMenu] = useState<ContextMenuState>({ visible: false, x: 0, y: 0, tabId: '' })

  // 支持鼠标滚轮水平滚动标签栏
  useEffect(() => {
    const tabList = tabListRef.current
    if (!tabList) return

    const handleWheel = (e: WheelEvent) => {
      // 只有当标签列表有水平滚动空间时才处理
      const hasHorizontalScroll = tabList.scrollWidth > tabList.clientWidth
      if (!hasHorizontalScroll) return
      
      // 阻止默认的垂直滚动
      e.preventDefault()
      e.stopPropagation()
      
      // 将垂直滚动转换为水平滚动
      tabList.scrollLeft += e.deltaY
    }

    // 使用 capture 阶段，确保事件能被捕获
    tabList.addEventListener('wheel', handleWheel, { passive: false, capture: true })
    return () => tabList.removeEventListener('wheel', handleWheel, { capture: true })
  }, [])

  // 自动滚动到活动标签
  useEffect(() => {
    if (!tabListRef.current || !activeTabId) return
    
    // 使用 requestAnimationFrame 确保 DOM 已更新
    requestAnimationFrame(() => {
      const activeTab = tabListRef.current?.querySelector('.tab-item.active')
      if (activeTab) {
        activeTab.scrollIntoView({ behavior: 'smooth', block: 'nearest', inline: 'nearest' })
      }
    })
  }, [activeTabId])

  const handleClose = useCallback((e: React.MouseEvent, tabId: string) => {
    e.stopPropagation()
    const tab = tabs.find(t => t.id === tabId)
    if (tab?.isModified) {
      const name = tab.filePath ? getFileName(tab.filePath) : '未命名'
      if (!confirm(`"${name}" 尚未保存，确定要关闭吗？`)) return
    }
    closeTab(tabId)
  }, [tabs, closeTab])

  // C-06: 右键菜单（带边界修正）
  const handleContextMenu = useCallback((e: React.MouseEvent, tabId: string) => {
    e.preventDefault()
    e.stopPropagation()
    const MENU_WIDTH = 170
    const MENU_HEIGHT = 140
    const x = Math.min(e.clientX, window.innerWidth - MENU_WIDTH)
    const y = Math.min(e.clientY, window.innerHeight - MENU_HEIGHT)
    setMenu({ visible: true, x: Math.max(0, x), y: Math.max(0, y), tabId })
  }, [])

  useEffect(() => {
    if (!menu.visible) return
    const handleClick = () => setMenu(prev => ({ ...prev, visible: false }))
    document.addEventListener('click', handleClick)
    return () => document.removeEventListener('click', handleClick)
  }, [menu.visible])

  const handleMenuClose = useCallback(() => {
    const tab = tabs.find(t => t.id === menu.tabId)
    if (tab?.isModified) {
      const name = tab.filePath ? getFileName(tab.filePath) : '未命名'
      if (!confirm(`"${name}" 尚未保存，确定要关闭吗？`)) return
    }
    closeTab(menu.tabId)
    setMenu(prev => ({ ...prev, visible: false }))
  }, [tabs, menu.tabId, closeTab])

  const handleMenuCloseOthers = useCallback(() => {
    const otherModified = tabs.filter(t => t.id !== menu.tabId && t.isModified)
    if (otherModified.length > 0) {
      const names = otherModified.map(t => t.filePath ? getFileName(t.filePath) : '未命名').join('、')
      if (!confirm(`以下文件尚未保存：${names}，确定要关闭吗？`)) return
    }
    closeOtherTabs(menu.tabId)
    setMenu(prev => ({ ...prev, visible: false }))
  }, [tabs, menu.tabId, closeOtherTabs])

  const handleMenuCloseAll = useCallback(() => {
    const modified = tabs.filter(t => t.isModified)
    if (modified.length > 0) {
      const names = modified.map(t => t.filePath ? getFileName(t.filePath) : '未命名').join('、')
      if (!confirm(`以下文件尚未保存：${names}，确定要关闭吗？`)) return
    }
    closeAllTabs()
    setMenu(prev => ({ ...prev, visible: false }))
  }, [tabs, closeAllTabs])

  const handleMenuCloseRight = useCallback(() => {
    const index = tabs.findIndex(t => t.id === menu.tabId)
    const rightTabs = tabs.slice(index + 1)
    const modified = rightTabs.filter(t => t.isModified)
    if (modified.length > 0) {
      const names = modified.map(t => t.filePath ? getFileName(t.filePath) : '未命名').join('、')
      if (!confirm(`以下文件尚未保存：${names}，确定要关闭吗？`)) return
    }
    closeTabsToRight(menu.tabId)
    setMenu(prev => ({ ...prev, visible: false }))
  }, [tabs, menu.tabId, closeTabsToRight])

  const hasRightTabs = menu.visible && (() => {
    const index = tabs.findIndex(t => t.id === menu.tabId)
    return index < tabs.length - 1
  })()

  if (tabs.length === 0) return null

  return (
    <div id="tab-bar">
      <div id="tab-list" ref={tabListRef}>
        {tabs.map(tab => (
          <div
            key={tab.id}
            className={`tab-item ${tab.id === activeTabId ? 'active' : ''} ${tab.isModified ? 'modified' : ''}`}
            onClick={() => switchToTab(tab.id)}
            onContextMenu={(e) => handleContextMenu(e, tab.id)}
          >
            <span className="tab-name">
              {tab.filePath ? getFileName(tab.filePath) : '未命名'}
            </span>
            <button
              className="tab-close"
              onClick={(e) => handleClose(e, tab.id)}
            >
              <Close size={10} />
            </button>
          </div>
        ))}
      </div>
      <button
        className="tab-add-btn"
        onClick={() => createTab(null, '')}
        title="新建标签页 (Ctrl+T)"
      >
        <Plus size={14} />
      </button>

      {/* 右键菜单 */}
      {menu.visible && (
        <div
          className="tab-context-menu" 
          style={{ left: menu.x, top: menu.y }}
          onClick={(e) => e.stopPropagation()}
        >
          <div className="tab-context-item" onClick={handleMenuClose}>
            关闭
          </div>
          {tabs.length > 1 && (
            <div className="tab-context-item" onClick={handleMenuCloseOthers}>
              关闭其他标签
            </div>
          )}
          {hasRightTabs && (
            <div className="tab-context-item" onClick={handleMenuCloseRight}>
              关闭右侧标签
            </div>
          )}
          <div className="tab-context-divider" />
          <div className="tab-context-item" onClick={handleMenuCloseAll}>
            关闭全部标签
          </div>
        </div>
      )}
    </div>
  )
}