import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:local_auth/local_auth.dart';
import 'package:url_launcher/url_launcher.dart';

import '../bloc/auth_bloc.dart';
import '../../../../core/config/environment.dart';
import '../../../../shared/design_system/unionflow_design_system.dart';
import '../../../../shared/widgets/powered_by_lions_dev.dart';

// ── Couleurs signature ────────────────────────────────────────────────────────
const _kGradTop     = Color(0xFF1D4ED8);
const _kGradMid     = Color(0xFF2563EB);
const _kGradBot     = Color(0xFF7616E8);
const _kPrimaryBlue = Color(0xFF2563EB);

/// UnionFlow — Écran de connexion.
/// Gradient signature (#1D4ED8 → #2563EB → #7616E8) + glassmorphism.
class LoginPage extends StatefulWidget {
  const LoginPage({super.key});

  @override
  State<LoginPage> createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> with TickerProviderStateMixin {
  late final AnimationController _fadeCtrl;
  late final AnimationController _slideCtrl;
  late final Animation<double> _fadeAnim;
  late final Animation<Offset> _slideAnim;

  bool _biometricAvailable = false;
  final _localAuth = LocalAuthentication();

  @override
  void initState() {
    super.initState();
    _fadeCtrl = AnimationController(
        vsync: this, duration: const Duration(milliseconds: 900));
    _slideCtrl = AnimationController(
        vsync: this, duration: const Duration(milliseconds: 750));
    _fadeAnim = CurvedAnimation(parent: _fadeCtrl, curve: Curves.easeOut);
    _slideAnim = Tween<Offset>(begin: const Offset(0, 0.12), end: Offset.zero)
        .animate(CurvedAnimation(parent: _slideCtrl, curve: Curves.easeOutCubic));
    _fadeCtrl.forward();
    _slideCtrl.forward();
    _checkBiometrics();
  }

  @override
  void dispose() {
    _fadeCtrl.dispose();
    _slideCtrl.dispose();
    super.dispose();
  }

  Future<void> _checkBiometrics() async {
    try {
      final canCheck  = await _localAuth.canCheckBiometrics;
      final supported = await _localAuth.isDeviceSupported();
      if (mounted) setState(() => _biometricAvailable = canCheck && supported);
    } catch (_) {}
  }

  Future<void> _authenticateBiometric() async {
    try {
      final ok = await _localAuth.authenticate(
        localizedReason: 'Authentifiez-vous pour accéder à UnionFlow',
        options: const AuthenticationOptions(stickyAuth: true, biometricOnly: false),
      );
      if (ok && mounted) context.read<AuthBloc>().add(const AuthStatusChecked());
    } catch (_) {}
  }

  Future<void> _openForgotPassword() async {
    final url = Uri.parse(
      '${AppConfig.keycloakRealmUrl}/protocol/openid-connect/auth'
      '?client_id=unionflow-mobile'
      '&redirect_uri=${Uri.encodeComponent('http://localhost')}'
      '&response_type=code&scope=openid&kc_action=reset_credentials',
    );
    try {
      if (await canLaunchUrl(url)) {
        await launchUrl(url, mode: LaunchMode.externalApplication);
      }
    } catch (_) {}
  }

  void _onAuthStateChanged(BuildContext context, AuthState state) {
    if (state is AuthError) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(state.message),
          backgroundColor: AppColors.error,
          behavior: SnackBarBehavior.floating,
          shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
        ),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: BlocConsumer<AuthBloc, AuthState>(
        listener: _onAuthStateChanged,
        builder: (context, state) {
          final isLoading = state is AuthLoading;
          return Stack(
            children: [
              const _GradientBackground(),
              const Positioned.fill(child: _HexPatternOverlay()),
              SafeArea(
                child: Center(
                  child: SingleChildScrollView(
                    padding: const EdgeInsets.symmetric(
                        horizontal: 28, vertical: 24),
                    child: FadeTransition(
                      opacity: _fadeAnim,
                      child: SlideTransition(
                        position: _slideAnim,
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            const _LoginLogoSection(),
                            const SizedBox(height: 16),
                            _LoginGlassCard(
                              isLoading: isLoading,
                              onLogin: () => context
                                  .read<AuthBloc>()
                                  .add(const AuthLoginRequested()),
                              onForgotPassword: _openForgotPassword,
                              biometricAvailable: _biometricAvailable,
                              onBiometric: _authenticateBiometric,
                            ),
                            const SizedBox(height: 24),
                            // Branding « Powered by Lions Dev » — fond toujours dark
                            const PoweredByLionsDev(forceBrightness: Brightness.dark),
                          ],
                        ),
                      ),
                    ),
                  ),
                ),
              ),
            ],
          );
        },
      ),
    );
  }
}

// ─────────────────────────────────────────────────────────────────────────────
// Widgets extraits
// ─────────────────────────────────────────────────────────────────────────────

class _GradientBackground extends StatelessWidget {
  const _GradientBackground();

  @override
  Widget build(BuildContext context) {
    return const DecoratedBox(
      decoration: BoxDecoration(
        gradient: LinearGradient(
          begin: Alignment.topLeft,
          end: Alignment.bottomRight,
          colors: [_kGradTop, _kGradMid, _kGradBot],
          stops: [0.0, 0.55, 1.0],
        ),
      ),
      child: SizedBox.expand(),
    );
  }
}

class _LoginLogoSection extends StatelessWidget {
  const _LoginLogoSection();

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Image.asset(
          'assets/images/unionflow-logo.png',
          width: 80,
          height: 80,
          fit: BoxFit.contain,
        ),
        const SizedBox(height: 10),
        Text(
          'UnionFlow',
          style: GoogleFonts.roboto(
            fontSize: 34,
            fontWeight: FontWeight.w700,
            color: Colors.white,
            letterSpacing: 0.3,
          ),
        ),
        const SizedBox(height: 6),
        Text(
          'Gérez votre organisation avec sérénité',
          style: GoogleFonts.roboto(
            fontSize: 13,
            color: Colors.white.withOpacity(0.78),
            letterSpacing: 0.2,
          ),
          textAlign: TextAlign.center,
        ),
      ],
    );
  }
}

class _LoginGlassCard extends StatelessWidget {
  const _LoginGlassCard({
    required this.isLoading,
    required this.onLogin,
    required this.onForgotPassword,
    required this.biometricAvailable,
    required this.onBiometric,
  });

  final bool isLoading;
  final VoidCallback onLogin;
  final VoidCallback onForgotPassword;
  final bool biometricAvailable;
  final VoidCallback onBiometric;

  @override
  Widget build(BuildContext context) {
    final isDark = Theme.of(context).brightness == Brightness.dark;
    return Container(
      decoration: BoxDecoration(
        color: Colors.white.withOpacity(0.11),
        borderRadius: BorderRadius.circular(16),
        border: Border.all(
            color: Colors.white.withOpacity(0.22), width: 1.5),
        boxShadow: [
          BoxShadow(
            color: AppColors.shadowStrong,
            blurRadius: 40,
            offset: const Offset(0, 10),
          ),
        ],
      ),
      padding: const EdgeInsets.fromLTRB(20, 20, 20, 16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Text(
            'Connexion',
            style: GoogleFonts.roboto(
              fontSize: 22,
              fontWeight: FontWeight.w600,
              color: Colors.white,
              letterSpacing: 0.1,
            ),
          ),
          const SizedBox(height: 4),
          Text(
            'Accédez à votre espace de travail',
            style: GoogleFonts.roboto(
              fontSize: 12.5,
              color: Colors.white.withOpacity(0.68),
              letterSpacing: 0.1,
            ),
          ),
          const SizedBox(height: 12),
          Align(
            alignment: Alignment.centerRight,
            child: TextButton(
              onPressed: onForgotPassword,
              style: TextButton.styleFrom(
                padding: EdgeInsets.zero,
                minimumSize: Size.zero,
                tapTargetSize: MaterialTapTargetSize.shrinkWrap,
              ),
              child: Text(
                'Mot de passe oublié ?',
                style: GoogleFonts.roboto(
                  fontSize: 12,
                  color: Colors.white,
                  fontWeight: FontWeight.w600,
                  decoration: TextDecoration.underline,
                  decorationColor: Colors.white.withOpacity(0.7),
                ),
              ),
            ),
          ),
          const SizedBox(height: 16),
          if (isLoading)
            const Center(
              child: CircularProgressIndicator(
                  color: Colors.white, strokeWidth: 2.5),
            )
          else
            ElevatedButton(
              onPressed: onLogin,
              style: ElevatedButton.styleFrom(
                backgroundColor: isDark ? AppColors.surfaceDark : AppColors.surface,
                foregroundColor: _kPrimaryBlue,
                padding: const EdgeInsets.symmetric(vertical: 10),
                shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(8)),
                elevation: 0,
              ),
              child: Text(
                'Se connecter',
                style: GoogleFonts.roboto(
                  fontSize: 15.5,
                  fontWeight: FontWeight.w700,
                  color: _kPrimaryBlue,
                  letterSpacing: 0.2,
                ),
              ),
            ),
          if (biometricAvailable) ...[
            const SizedBox(height: 14),
            Center(
              child: TextButton.icon(
                onPressed: onBiometric,
                icon: const Icon(Icons.fingerprint_rounded,
                    color: Colors.white60, size: 22),
                label: Text(
                  'Connexion biométrique',
                  style: GoogleFonts.roboto(
                      fontSize: 12.5, color: Colors.white60),
                ),
                style: TextButton.styleFrom(
                  padding:
                      const EdgeInsets.symmetric(horizontal: 8, vertical: 6),
                ),
              ),
            ),
          ],
        ],
      ),
    );
  }
}

// ─────────────────────────────────────────────────────────────────────────────
// Painters
// ─────────────────────────────────────────────────────────────────────────────

class _HexPatternOverlay extends StatelessWidget {
  const _HexPatternOverlay();

  @override
  Widget build(BuildContext context) =>
      CustomPaint(painter: _HexPatternPainter());
}

class _HexPatternPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.white.withOpacity(0.045)
      ..style = PaintingStyle.stroke
      ..strokeWidth = 0.8;

    const r      = 22.0;
    const hSpace = r * 1.75;
    const vSpace = r * 1.52;

    for (double row = -1; row * vSpace < size.height + vSpace; row++) {
      final offset = (row % 2 == 0) ? 0.0 : hSpace / 2;
      for (double col = -1;
          col * hSpace - offset < size.width + hSpace;
          col++) {
        _hexagon(canvas, paint,
            Offset(col * hSpace + offset, row * vSpace), r);
      }
    }
  }

  void _hexagon(Canvas canvas, Paint paint, Offset center, double r) {
    final path = Path();
    for (int i = 0; i < 6; i++) {
      final a = (i * 60 - 30) * math.pi / 180;
      final p = Offset(
          center.dx + r * math.cos(a), center.dy + r * math.sin(a));
      i == 0 ? path.moveTo(p.dx, p.dy) : path.lineTo(p.dx, p.dy);
    }
    path.close();
    canvas.drawPath(path, paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}