/**
 * Layout.tsx — 전체 페이지 레이아웃 컴포넌트
 *
 * 역할:
 * - 상단 네비게이션 바 (브랜드 로고, 메뉴, 연결 상태 표시기)
 * - 백엔드 및 MCP 서버 연결 상태 실시간 모니터링 (5초 폴링)
 * - children으로 전달된 페이지 컨텐츠 렌더링
 *
 * 구조:
 *   [Header] — sticky 상단 바 (z-50)
 *     - 브랜드 로고 (AutoStock)
 *     - 네비게이션 링크 (대시보드, 성과분석, 전략설정, 백테스트, 매매로그, MCP상태)
 *     - 연결 상태 표시 (Backend LIVE/OFFLINE, MCP connected/unknown)
 *   [Main] — 페이지 컨텐츠 영역
 */
import { Link, useLocation } from 'react-router-dom'
import { LayoutDashboard, History, Cpu, Activity, SlidersHorizontal, BarChart3, TrendingUp } from 'lucide-react'
import { useQuery } from '@tanstack/react-query'
import api from '../lib/api'

/** Layout Props 정의 */
interface LayoutProps {
    children: React.ReactNode
}

/**
 * Layout — 전체 페이지 레이아웃 (헤더 + 컨텐츠)
 *
 * 쿼리:
 * - backend-health: 백엔드 연결 상태 확인 (portfolio API 호출, 3초 타임아웃)
 * - mcp-status: MCP 서버 연결 상태 확인
 */
const Layout = ({ children }: LayoutProps) => {
    const location = useLocation()

    // 백엔드 연결 상태 확인 (30초 폴링, 3초 타임아웃 — /health 경량 엔드포인트 사용)
    const { data: healthData } = useQuery({
        queryKey: ['backend-health'],
        queryFn: async () => {
            try {
                const r = await fetch('/health', {
                    signal: AbortSignal.timeout(3000),
                })
                return r.ok
            } catch { return false }
        },
        refetchInterval: 30000,
    })
    const backendConnected = healthData === true

    const { data: mcpStatus } = useQuery({
        queryKey: ['mcp-status'],
        queryFn: async () => {
            try {
                return (await api.get('/mcp/status')).data
            } catch { return null }
        },
        refetchInterval: 5000,
    })

    /** 네비게이션 메뉴 항목 (경로, 아이콘, 레이블) */
    const navItems = [
        { path: '/', icon: LayoutDashboard, label: '대시보드' },
        { path: '/analysis', icon: TrendingUp, label: '성과 분석' },
        { path: '/strategy', icon: SlidersHorizontal, label: '전략 설정' },
        { path: '/backtest', icon: BarChart3, label: '백테스트' },
        { path: '/trades', icon: History, label: '매매 로그' },
        { path: '/mcp', icon: Cpu, label: 'MCP 상태' },
    ]

    return (
        <div className="min-h-screen bg-[#0f1115] text-gray-100 font-sans flex flex-col">
            {/* Top Navigation Bar */}
            <header className="border-b border-gray-800 bg-[#161b22] h-16 flex items-center justify-between px-6 sticky top-0 z-50 backdrop-blur-md bg-opacity-90">
                <div className="flex items-center gap-8">
                    {/* Brand */}
                    <div className="flex items-center gap-3">
                        <div className="bg-blue-600 p-2 rounded-lg shadow-lg shadow-blue-500/20">
                            <Activity className="text-white" size={20} />
                        </div>
                        <h1 className="text-lg font-semibold tracking-tight leading-none">AutoStock</h1>
                    </div>

                    {/* Navigation */}
                    <nav className="flex items-center gap-1">
                        {navItems.map((item) => {
                            const Icon = item.icon
                            const isActive = location.pathname === item.path
                            return (
                                <Link
                                    key={item.path}
                                    to={item.path}
                                    className={`flex items-center gap-2 px-3 py-2 rounded-md transition-all text-sm font-medium ${isActive
                                        ? 'bg-gray-800 text-blue-400'
                                        : 'text-gray-400 hover:text-white hover:bg-gray-800/50'
                                        }`}
                                >
                                    <Icon size={16} />
                                    <span>{item.label}</span>
                                </Link>
                            )
                        })}
                    </nav>
                </div>

                {/* Status Indicators */}
                <div className="flex items-center gap-4">
                    <div className="flex items-center gap-2 px-3 py-1.5 bg-gray-800/50 rounded-full border border-gray-700/50">
                        <div className={`w-2 h-2 rounded-full ${backendConnected ? 'bg-green-500 shadow-[0_0_8px_rgba(34,197,94,0.5)]' : 'bg-red-500'}`} />
                        <span className="text-xs text-gray-400">{backendConnected ? 'LIVE' : 'OFFLINE'}</span>
                    </div>
                    <div className="flex items-center gap-2 px-3 py-1.5 bg-gray-800/50 rounded-full border border-gray-700/50">
                        <div className={`w-2 h-2 rounded-full ${mcpStatus?.status === 'connected' ? 'bg-blue-500 shadow-[0_0_8px_rgba(59,130,246,0.5)]' : 'bg-yellow-500'}`} />
                        <span className="text-xs text-gray-400">MCP: {mcpStatus?.status || 'Unknown'}</span>
                    </div>
                </div>
            </header>

            {/* Main Content Area */}
            <main className="flex-1 overflow-x-hidden">
                {children}
            </main>
        </div>
    )
}

export default Layout