/**
 * Admin 后台 - 布局组件(报刊风)
 *
 * 与前台同一套纸色语言:报头式侧栏 + 报眉顶栏 + 细线分区。
 * 响应式: 移动端汉堡菜单 + 抽屉侧栏,桌面端固定侧栏。
 */

import { useState, useEffect, useCallback } from 'react'
import { NavLink, Outlet, useLocation } from 'react-router-dom'
import { fetchAuthState, logout, UNAUTHORIZED_EVENT } from '../api/api'
import { fetchHealth } from '../api/dal'
import { COMMAND_PALETTE_PAGES, ROUTE_LABELS, NAV_SECTIONS } from './nav'
import Login from './Login'
import { useCommandPalette, CommandPalette } from './useCommandPalette'
import { AdminIcon } from './AdminIcon'

// 图标已抽到 ./AdminIcon —— 此前这里是约 90 行的内联 switch,
// 让布局文件同时承担页面骨架与图标图形库两种职责。

/**
 * 侧栏导航项的 className 生成器。
 *
 * 此前这段字符串在文件里出现了两次(仪表盘项 + 分组循环项),
 * 逐字相同。改一次选中态样式要改两处 —— 与 App.tsx 里
 * 被抽成 SiteLayout 的重复是同一型问题,这里同样收敛为单一来源。
 */
const SIDEBAR_LINK_BASE = 'nav-icon-wrap flex min-h-[40px] items-center gap-2.5 border-l-4 px-3 text-sm transition-all duration-300'
const SIDEBAR_LINK_ACTIVE = 'border-press bg-press-wash/60 font-medium text-press active'
const SIDEBAR_LINK_IDLE = 'border-transparent text-ink-500 hover:bg-paper-100 hover:text-ink-900'

function sidebarLinkClass({ isActive }: { isActive: boolean }): string {
  return `${SIDEBAR_LINK_BASE} ${isActive ? SIDEBAR_LINK_ACTIVE : SIDEBAR_LINK_IDLE}`
}

// D6: 导航三视图(侧栏/命令面板/面包屑)统一由 admin/nav.ts 的 NAV_ITEMS
// 单源派生 —— 此处的 NAV_PAGES/ROUTE_LABELS/NAV_SECTIONS 平行清单已删除,
// 新增页面/改标签只改 nav.ts 一处。

/** 报眉日期行,与前台同款式 */
function dateLine(): string {
  return new Date().toLocaleDateString('zh-CN', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    weekday: 'long',
  })
}

export default function AdminLayout() {
  const [sidebarOpen, setSidebarOpen] = useState(false)
  const [healthOk, setHealthOk] = useState<boolean | null>(null)
  const [authed, setAuthed] = useState<boolean | null>(null)
  const location = useLocation()
  const palette = useCommandPalette(COMMAND_PALETTE_PAGES)

  // 登录门禁:挂载时探测会话,收到 401 事件(会话过期)自动切回登录页
  useEffect(() => {
    let alive = true
    fetchAuthState()
      .then(s => alive && setAuthed(s.authenticated))
      .catch(() => alive && setAuthed(false))
    const onUnauthorized = () => setAuthed(false)
    window.addEventListener(UNAUTHORIZED_EVENT, onUnauthorized)
    return () => {
      alive = false
      window.removeEventListener(UNAUTHORIZED_EVENT, onUnauthorized)
    }
  }, [])

  const handleLogout = useCallback(async () => {
    try {
      await logout()
    } catch {
      /* 会话可能已失效,直接切回登录页 */
    }
    setAuthed(false)
  }, [])

  const checkHealth = useCallback(async () => {
    try {
      const h = await fetchHealth()
      setHealthOk(h?.status === 'healthy' || h?.status === 'ok')
    } catch {
      setHealthOk(false)
    }
  }, [])

  useEffect(() => {
    checkHealth()
    const t = setInterval(checkHealth, 60_000)
    return () => clearInterval(t)
  }, [checkHealth])

  // 路由变化时关闭移动端菜单
  const closeSidebar = useCallback(() => setSidebarOpen(false), [])
  useEffect(() => {
    closeSidebar()
  }, [location.pathname, closeSidebar])

  // ESC 键关闭菜单
  useEffect(() => {
    const handler = (e: KeyboardEvent) => {
      if (e.key === 'Escape') setSidebarOpen(false)
    }
    document.addEventListener('keydown', handler)
    return () => document.removeEventListener('keydown', handler)
  }, [])

  // 登录门禁:未登录只渲染登录页,不泄露后台任何内容
  if (authed === null) {
    return (
      <div className="flex h-screen items-center justify-center bg-paper-50 text-xs text-ink-400">
        正在验证登录状态…
      </div>
    )
  }
  if (!authed) {
    return <Login onSuccess={() => setAuthed(true)} />
  }

  return (
    <div className="flex h-screen flex-col overflow-hidden bg-paper-50 text-ink-800">
      {/* ── 通栏顶部报眉 ── */}
      <header className="flex h-11 flex-shrink-0 items-center justify-between border-b border-ink-200 bg-paper-50 px-4 lg:px-6">
        <div className="flex items-center gap-4">
          {/* 移动端汉堡按钮 */}
          <button
            onClick={() => setSidebarOpen(true)}
            className="-ml-1 p-2 text-ink-500 hover:text-ink-900 lg:hidden"
            aria-label="打开菜单"
          >
            <svg className="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 6h16M4 12h16M4 18h16" />
            </svg>
          </button>
          {/* 面包屑 */}
          <nav className="hidden items-center gap-1.5 text-2xs text-ink-400 sm:flex" aria-label="面包屑">
            <a href="/admin" className="hover:text-ink-700">仪表盘</a>
            {location.pathname !== '/admin' && (
              <>
                <span aria-hidden="true">/</span>
                <span className="text-ink-600">{ROUTE_LABELS[location.pathname] ?? '未知页面'}</span>
              </>
            )}
          </nav>
          <span className="hidden text-2xs text-ink-500 sm:inline">{dateLine()}</span>
        </div>

        <div className="flex items-center gap-4 text-2xs">
          <span className="inline-flex items-center gap-1.5 text-ink-500">
            <span
              className={`inline-block h-1.5 w-1.5 ${
                healthOk === null ? 'bg-ink-300' : healthOk ? 'bg-ink-900' : 'bg-press'
              }`}
              aria-hidden="true"
            />
            {healthOk === null ? '检测中' : healthOk ? '系统正常' : '系统异常'}
          </span>
          <button
            onClick={handleLogout}
            className="text-ink-500 transition-colors hover:text-press"
            title="退出登录"
          >
            登出
          </button>
        </div>
      </header>

      {/* ── 主体:侧边栏 + 内容 ── */}
      <div className="flex flex-1 overflow-hidden">
      {/* ── 移动端遮罩层 ── */}
      {sidebarOpen && (
        <div
          className="fixed inset-0 z-40 bg-ink-900/40 lg:hidden"
          onClick={() => setSidebarOpen(false)}
          aria-hidden="true"
        />
      )}

      {/* ── 侧边栏 ── */}
      <aside
        className={`
          fixed inset-y-0 left-0 z-50 flex w-60 flex-shrink-0 flex-col border-r border-ink-900 bg-paper-50
          transform transition-transform duration-200 ease-in-out
          lg:relative lg:z-auto lg:translate-x-0
          ${sidebarOpen ? 'translate-x-0' : '-translate-x-full'}
        `}
        aria-label="主导航"
      >
        {/* 侧栏顶部 */}
        <div className="flex items-center justify-center border-b border-ink-900 px-5 py-5">
          <h1 className="text-center text-3xl tracking-wide text-ink-900 font-brush">先知</h1>
        </div>

        {/* 导航:分组 + 小节标题 */}
        <nav className="flex-1 overflow-y-auto px-3 py-3" aria-label="管理导航">
          {/* 仪表盘独立(始终第一项) */}
          <NavLink to="/admin" end className={sidebarLinkClass}>
            <AdminIcon name="chart" />
            仪表盘
          </NavLink>

          {NAV_SECTIONS.map(section => (
            <div key={section.title} className="mt-4">
              <p className="mb-1 px-3 text-2xs font-medium uppercase tracking-widest text-ink-400">
                {section.title}
              </p>
              <ul className="space-y-0.5">
                {section.items.map(item => (
                  <li key={item.to}>
                    <NavLink to={item.to} className={sidebarLinkClass}>
                      <AdminIcon name={item.icon} />
                      {item.label}
                    </NavLink>
                  </li>
                ))}
              </ul>
            </div>
          ))}
        </nav>

        {/* 底部 */}
        <div className="border-t border-ink-200 px-4 py-3 space-y-2">
          <a
            href="/"
            className="flex min-h-[36px] items-center gap-2 text-xs text-ink-500 transition-colors hover:text-press"
          >
            <span aria-hidden="true">←</span>
            返回前台版面
          </a>
          <p className="text-2xs text-ink-300">v1.0</p>
        </div>
      </aside>

      {/* ── 主内容区 ── */}
      <main className="flex-1 overflow-y-auto p-4 lg:p-8" key={location.pathname}>
        <div className="mx-auto max-w-6xl page-content-enter">
          <Outlet />
        </div>
      </main>
      </div>

      {/* 命令面板(⌘K) */}
      <CommandPalette
        open={palette.open}
        query={palette.query}
        setQuery={palette.setQuery}
        items={palette.items}
        onClose={() => palette.setOpen(false)}
      />
    </div>
  )
}