import 'package:flutter/material.dart';
import 'package:mobile_scanner/mobile_scanner.dart';
import 'package:go_router/go_router.dart';
import 'package:logging/logging.dart';
import '../../../core/services/auth_proxy_service.dart';
import '../../../core/services/auth_token_store.dart';

class QRScanScreen extends StatefulWidget {
  const QRScanScreen({super.key});

  @override
  State<QRScanScreen> createState() => _QRScanScreenState();
}

class _QRScanScreenState extends State<QRScanScreen> {
  final _log = Logger('QRScanScreen');
  final MobileScannerController controller = MobileScannerController(
    detectionSpeed: DetectionSpeed.noDuplicates,
  );
  bool _isScanned = false;
  bool _isCheckingSession = false;
  bool _isProcessing = false;
  bool _isRequestingCamera = false;
  bool? _isSuccess;
  String? _resultMessage;

  @override
  void initState() {
    super.initState();
    _bootstrapCookieSession();
  }

  Future<bool> _bootstrapCookieSession() async {
    if (AuthTokenStore.usesCookie()) {
      return true;
    }
    if (_isCheckingSession) {
      return false;
    }
    setState(() => _isCheckingSession = true);
    try {
      await AuthProxyService.checkCookieSession();
      AuthTokenStore.setCookieMode(provider: 'ory');
      return true;
    } catch (e) {
      _log.info('Cookie session check failed: $e');
      return false;
    } finally {
      if (mounted) {
        setState(() => _isCheckingSession = false);
      }
    }
  }

  @override
  void dispose() {
    controller.dispose();
    super.dispose();
  }

  Future<void> _onDetect(BarcodeCapture capture) async {
    if (_isScanned) return;
    
    final List<Barcode> barcodes = capture.barcodes;
    for (final barcode in barcodes) {
      if (barcode.rawValue != null) {
        _isScanned = true;
        if (mounted) {
          setState(() => _isProcessing = true);
        }
        String qrData = barcode.rawValue!;
        String pendingRef = qrData;

        // URL 형식이라면 'ref' 파라미터 추출 시도
        if (qrData.startsWith('http')) {
          try {
            final uri = Uri.parse(qrData);
            if (uri.queryParameters.containsKey('ref')) {
              pendingRef = uri.queryParameters['ref']!;
            } else if (uri.pathSegments.isNotEmpty) {
              final segments = uri.pathSegments;
              final qlIndex = segments.indexOf('ql');
              if (qlIndex != -1 && qlIndex + 1 < segments.length) {
                pendingRef = segments[qlIndex + 1];
              }
            }
          } catch (e) {
            _log.warning('Failed to parse QR URL: $qrData', e);
          }
        }

        _log.info('QR Code detected raw: $qrData, ref: $pendingRef');
        final approveRef = qrData;
        
        final storedToken = AuthTokenStore.getToken();
        final sessionToken = storedToken;
        var usesCookie = AuthTokenStore.usesCookie();
        if (sessionToken == null && !usesCookie) {
          usesCookie = await _bootstrapCookieSession();
        }
        if (sessionToken == null && !usesCookie) {
          if (mounted) {
            context.go('/signin?notice=qr_login_required');
          }
          return;
        }

        try {
          // Call backend API to approve login with clean ref
          await AuthProxyService.approveQrLogin(
            approveRef,
            token: sessionToken,
            withCredentials: usesCookie,
          );
          
          if (mounted) {
            setState(() {
              _isSuccess = true;
              _resultMessage = 'QR 승인 완료! PC 화면에서 로그인이 진행됩니다.';
              _isProcessing = false;
            });
          }
        } catch (e) {
          _log.severe("QR Approval Failed", e);
          if (mounted) {
            setState(() {
              _isSuccess = false;
              _resultMessage = 'QR 승인 실패: $e';
              _isProcessing = false;
            });
          }
        }
        break;
      }
    }
  }

  void _resetScan() {
    setState(() {
      _isScanned = false;
      _isProcessing = false;
      _isSuccess = null;
      _resultMessage = null;
    });
    controller.start();
  }

  Future<void> _requestCameraPermission() async {
    if (_isRequestingCamera) return;
    setState(() => _isRequestingCamera = true);
    try {
      await controller.start();
    } catch (e) {
      _log.warning('Camera permission request failed: $e');
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('카메라 권한 요청에 실패했습니다. 브라우저/OS 설정을 확인해주세요.'),
            backgroundColor: Colors.red,
          ),
        );
      }
    } finally {
      if (mounted) {
        setState(() => _isRequestingCamera = false);
      }
    }
  }

  Widget _buildResultView() {
    final success = _isSuccess == true;
    final icon = success ? Icons.check_circle_outline : Icons.error_outline;
    final color = success ? Colors.green : Colors.red;
    final title = success ? '승인 완료' : '승인 실패';
    final message = _resultMessage ?? '';

    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(icon, color: color, size: 72),
            const SizedBox(height: 16),
            Text(
              title,
              style: TextStyle(fontSize: 22, fontWeight: FontWeight.bold, color: color),
            ),
            const SizedBox(height: 12),
            Text(
              message,
              textAlign: TextAlign.center,
              style: const TextStyle(color: Colors.black54),
            ),
            const SizedBox(height: 24),
            if (!success)
              FilledButton(
                onPressed: _resetScan,
                child: const Text('다시 스캔'),
              ),
            if (success)
              FilledButton(
                onPressed: () => context.pop(),
                child: const Text('닫기'),
              ),
          ],
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Scan QR Code'),
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: () => context.pop(),
        ),
      ),
      body: _isSuccess == null
          ? Stack(
              children: [
                MobileScanner(
                  controller: controller,
                  onDetect: _onDetect,
                  errorBuilder: (context, error) {
                    final isPermissionDenied = error.errorCode ==
                        MobileScannerErrorCode.permissionDenied;
                    return Center(
                      child: Column(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          const Icon(Icons.error, color: Colors.red, size: 50),
                          const SizedBox(height: 10),
                          Text(
                            isPermissionDenied
                                ? '카메라 권한이 필요합니다.'
                                : '카메라 오류: ${error.errorCode}',
                          ),
                          const SizedBox(height: 12),
                          FilledButton(
                            onPressed: _isRequestingCamera
                                ? null
                                : _requestCameraPermission,
                            child: Text(
                              _isRequestingCamera
                                  ? '요청 중...'
                                  : '카메라 권한 요청하기',
                            ),
                          ),
                        ],
                      ),
                    );
                  },
                ),
                if (_isProcessing || _isCheckingSession)
                  const Center(child: CircularProgressIndicator()),
              ],
            )
          : _buildResultView(),
    );
  }
}