import "dart:io" show Platform;
import "dart:convert";
import "package:flutter/material.dart";
import "package:flutter/services.dart";
import "package:flutter_inappwebview/flutter_inappwebview.dart";
import "package:url_launcher/url_launcher.dart";

import "app_config.dart";
import "services/lock_service.dart";
import "services/push_service.dart";

const _navy = Color(0xFF03143F);

class WebViewScreen extends StatefulWidget {
  const WebViewScreen({super.key});
  @override
  State<WebViewScreen> createState() => _WebViewScreenState();
}

class _WebViewScreenState extends State<WebViewScreen> with WidgetsBindingObserver {
  InAppWebViewController? _controller;
  late final PullToRefreshController _pullToRefresh;
  String? _ua; // 기본 UA + spinApp 태그
  bool _loading = true;
  bool _offline = false;
  bool _locked = false;
  DateTime? _pausedAt;
  bool _registeredToken = false;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _pullToRefresh = PullToRefreshController(
      settings: PullToRefreshSettings(color: _navy),
      onRefresh: () async {
        if (Platform.isAndroid) {
          _controller?.reload();
        } else {
          final url = await _controller?.getUrl();
          if (url != null) _controller?.loadUrl(urlRequest: URLRequest(url: url));
        }
      },
    );
    _initUA();
    _maybeLockOnStart();
    // 토큰이 늦게 도착하면 등록 주입
    PushService.instance.token.addListener(_injectTokenRegistration);
    // 푸시 탭 이동
    PushService.instance.pendingLink.addListener(_consumePendingLink);
  }

  Future<void> _initUA() async {
    String base = "";
    try {
      base = await InAppWebViewController.getDefaultUserAgent();
    } catch (_) {}
    setState(() => _ua = "$base ${AppConfig.userAgentTag}".trim());
  }

  Future<void> _maybeLockOnStart() async {
    if (await LockService.instance.isEnabled()) {
      setState(() => _locked = true);
      _tryUnlock();
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    PushService.instance.token.removeListener(_injectTokenRegistration);
    PushService.instance.pendingLink.removeListener(_consumePendingLink);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) async {
    if (state == AppLifecycleState.paused) {
      _pausedAt = DateTime.now();
    } else if (state == AppLifecycleState.resumed) {
      final enabled = await LockService.instance.isEnabled();
      final elapsed = _pausedAt == null ? Duration.zero : DateTime.now().difference(_pausedAt!);
      if (enabled && elapsed > AppConfig.lockGracePeriod && !_locked) {
        setState(() => _locked = true);
        _tryUnlock();
      }
    }
  }

  Future<void> _tryUnlock() async {
    final ok = await LockService.instance.authenticate();
    if (ok && mounted) setState(() => _locked = false);
  }

  // FCM 토큰을 웹 세션(쿠키 보유)으로 전달해 /api/devices 에 등록.
  void _injectTokenRegistration() {
    final t = PushService.instance.token.value;
    if (t == null || _controller == null) return;
    final platform = Platform.isIOS ? "ios" : "android";
    final body = jsonEncode({"token": t, "platform": platform});
    _controller!.evaluateJavascript(source: """
      try { fetch('/api/devices', {method:'POST', headers:{'Content-Type':'application/json'}, credentials:'include', body: ${jsonEncode(body)} }); } catch(e) {}
    """);
    _registeredToken = true;
  }

  void _consumePendingLink() {
    final link = PushService.instance.pendingLink.value;
    if (link == null || _controller == null) return;
    _controller!.loadUrl(urlRequest: URLRequest(url: WebUri("${AppConfig.baseUrl}$link")));
    PushService.instance.pendingLink.value = null;
  }

  Future<void> _reload() async {
    setState(() {
      _offline = false;
      _loading = true;
    });
    _controller?.loadUrl(urlRequest: URLRequest(url: WebUri(AppConfig.baseUrl)));
  }

  @override
  Widget build(BuildContext context) {
    if (_ua == null) {
      return const Scaffold(backgroundColor: _navy, body: Center(child: CircularProgressIndicator(color: Colors.white)));
    }
    return PopScope(
      canPop: false,
      onPopInvokedWithResult: (didPop, _) async {
        if (didPop) return;
        final messenger = ScaffoldMessenger.of(context); // capture before await
        if (_controller != null && await _controller!.canGoBack()) {
          _controller!.goBack();
        } else {
          // 더블탭 종료
          final now = DateTime.now();
          if (_lastBack == null || now.difference(_lastBack!) > const Duration(seconds: 2)) {
            _lastBack = now;
            messenger.showSnackBar(
              const SnackBar(content: Text("한 번 더 누르면 종료됩니다"), duration: Duration(seconds: 2)),
            );
          } else {
            SystemNavigator.pop();
          }
        }
      },
      child: Scaffold(
        backgroundColor: _navy,
        body: SafeArea(
          top: false, // 상·하단 모두 웹의 safe-area CSS(env)가 처리 — 셸은 inset을 잡지 않는다
          bottom: false,
          child: Stack(
            children: [
              InAppWebView(
                initialUrlRequest: URLRequest(url: WebUri(AppConfig.baseUrl)),
                initialSettings: InAppWebViewSettings(
                  userAgent: _ua,
                  javaScriptEnabled: true,
                  cacheEnabled: true,
                  clearCache: false,
                  transparentBackground: true,
                  useOnDownloadStart: true,
                  mediaPlaybackRequiresUserGesture: false,
                  allowsInlineMediaPlayback: true,
                  supportZoom: false,
                  useHybridComposition: true,
                  allowFileAccess: true,
                  javaScriptCanOpenWindowsAutomatically: false,
                ),
                pullToRefreshController: _pullToRefresh,
                onWebViewCreated: (c) => _controller = c,
                onLoadStart: (_, __) => setState(() => _loading = true),
                onProgressChanged: (_, p) {
                  if (p == 100) _pullToRefresh.endRefreshing();
                },
                onLoadStop: (_, __) {
                  _pullToRefresh.endRefreshing();
                  setState(() => _loading = false);
                  if (!_registeredToken) _injectTokenRegistration();
                  _consumePendingLink();
                },
                onReceivedError: (_, req, __) {
                  if (req.isForMainFrame ?? true) setState(() => _offline = true);
                  _pullToRefresh.endRefreshing();
                },
                onPermissionRequest: (_, req) async =>
                    PermissionResponse(resources: req.resources, action: PermissionResponseAction.GRANT),
                shouldOverrideUrlLoading: (_, action) async {
                  final uri = action.request.url;
                  if (uri == null) return NavigationActionPolicy.ALLOW;
                  final scheme = uri.scheme.toLowerCase();
                  // 외부 스킴은 시스템에서 (전화/메일/지도 등)
                  if (scheme != "http" && scheme != "https") {
                    if (await canLaunchUrl(uri)) launchUrl(uri, mode: LaunchMode.externalApplication);
                    return NavigationActionPolicy.CANCEL;
                  }
                  // 타 호스트(외부 사이트)는 시스템 브라우저로 — 단 Keycloak 등 인증 호스트는 인앱 유지
                  if (uri.host != AppConfig.baseUri.host && !_isAuthHost(uri.host)) {
                    if (await canLaunchUrl(uri)) launchUrl(uri, mode: LaunchMode.externalApplication);
                    return NavigationActionPolicy.CANCEL;
                  }
                  return NavigationActionPolicy.ALLOW;
                },
              ),
              if (_loading && !_offline)
                Container(color: _navy, child: const Center(child: CircularProgressIndicator(color: Colors.white))),
              if (_offline) _OfflineView(onRetry: _reload),
              if (_locked) _LockOverlay(onUnlock: _tryUnlock),
            ],
          ),
        ),
      ),
    );
  }

  DateTime? _lastBack;

  // 로그인 리다이렉트가 Keycloak/oauth2-proxy 등 타 호스트로 가더라도 인앱 유지.
  bool _isAuthHost(String host) {
    return host.contains("keycloak") ||
        host.contains("auth") ||
        host.contains("oauth2") ||
        host.endsWith("special-partners.com");
  }
}

class _OfflineView extends StatelessWidget {
  const _OfflineView({required this.onRetry});
  final VoidCallback onRetry;
  @override
  Widget build(BuildContext context) {
    return Container(
      color: const Color(0xFFF5F6F8),
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.wifi_off_rounded, size: 44, color: Color(0xFF98A2B3)),
            const SizedBox(height: 12),
            const Text("연결할 수 없습니다", style: TextStyle(fontSize: 16, fontWeight: FontWeight.w700, color: Color(0xFF101828))),
            const SizedBox(height: 4),
            const Text("네트워크 상태를 확인해 주세요", style: TextStyle(fontSize: 13, color: Color(0xFF667085))),
            const SizedBox(height: 16),
            FilledButton(
              style: FilledButton.styleFrom(backgroundColor: _navy),
              onPressed: onRetry,
              child: const Text("다시 시도"),
            ),
          ],
        ),
      ),
    );
  }
}

class _LockOverlay extends StatelessWidget {
  const _LockOverlay({required this.onUnlock});
  final VoidCallback onUnlock;
  @override
  Widget build(BuildContext context) {
    return Container(
      color: _navy,
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.lock_rounded, size: 48, color: Colors.white),
            const SizedBox(height: 16),
            const Text("잠금 상태입니다", style: TextStyle(color: Colors.white, fontSize: 16, fontWeight: FontWeight.w700)),
            const SizedBox(height: 16),
            OutlinedButton(
              style: OutlinedButton.styleFrom(foregroundColor: Colors.white, side: const BorderSide(color: Colors.white54)),
              onPressed: onUnlock,
              child: const Text("잠금 해제"),
            ),
          ],
        ),
      ),
    );
  }
}