// lib/screens/desktop_login_screen.dart

import 'package:flutter/material.dart';
import '../core/utils/error_utils.dart';
import '../features/auth/services/auth_service.dart';
import '../core/auth/auth_guard.dart';
import 'home_desktop_screen.dart';
import '../core/app_decoration.dart';

class DesktopLoginScreen extends StatefulWidget {
  const DesktopLoginScreen({Key? key}) : super(key: key);

  @override
  State<DesktopLoginScreen> createState() => _DesktopLoginScreenState();
}

class _DesktopLoginScreenState extends State<DesktopLoginScreen> with SingleTickerProviderStateMixin {
  // Login controllers
  final TextEditingController _emailCtrl = TextEditingController();
  final TextEditingController _passCtrl = TextEditingController();

  // Signup controllers
  final TextEditingController _signupEmailCtrl = TextEditingController();
  final TextEditingController _signupPhoneCtrl = TextEditingController();
  final TextEditingController _signupPassCtrl = TextEditingController();
  final TextEditingController _signupConfirmCtrl = TextEditingController();
  String? _signupDistrict;

  static const _districts = [
    'Thiruvananthapuram', 'Kollam', 'Pathanamthitta', 'Alappuzha',
    'Kottayam', 'Idukki', 'Ernakulam', 'Thrissur', 'Palakkad',
    'Malappuram', 'Kozhikode', 'Wayanad', 'Kannur', 'Kasaragod',
  ];

  final AuthService _auth = AuthService();

  AnimationController? _controller;
  Animation<double>? _leftWidthAnim;
  Animation<double>? _leftTextOpacityAnim;
  Animation<double>? _formOpacityAnim;
  Animation<double>? _formOffsetAnim;

  final double _collapsedWidth = 220;
  final Duration _duration = const Duration(milliseconds: 700);
  final Curve _curve = Curves.easeInOutCubic;

  bool _isAnimating = false;
  bool _loading = false;
  bool _isSignupMode = false;

  @override
  void dispose() {
    _controller?.dispose();
    _emailCtrl.dispose();
    _passCtrl.dispose();
    _signupEmailCtrl.dispose();
    _signupPhoneCtrl.dispose();
    _signupPassCtrl.dispose();
    _signupConfirmCtrl.dispose();
    super.dispose();
  }

  Future<void> _startCollapseAnimation(double initialLeftWidth) async {
    _controller?.dispose();

    _controller = AnimationController(vsync: this, duration: _duration);

    _leftWidthAnim = Tween<double>(begin: initialLeftWidth, end: _collapsedWidth).animate(
      CurvedAnimation(parent: _controller!, curve: _curve),
    );
    _leftTextOpacityAnim = Tween<double>(begin: 1.0, end: 0.0).animate(
      CurvedAnimation(parent: _controller!, curve: const Interval(0.0, 0.35, curve: Curves.easeOut)),
    );
    _formOpacityAnim = Tween<double>(begin: 1.0, end: 0.0).animate(
      CurvedAnimation(parent: _controller!, curve: const Interval(0.0, 0.55, curve: Curves.easeOut)),
    );
    _formOffsetAnim = Tween<double>(begin: 0.0, end: -60.0).animate(
      CurvedAnimation(parent: _controller!, curve: const Interval(0.0, 0.55, curve: Curves.easeOut)),
    );

    setState(() => _isAnimating = true);
    await _controller!.forward();
    await Future.delayed(const Duration(milliseconds: 120));
  }

  Future<void> _performLoginFlow(double initialLeftWidth) async {
    if (_isAnimating || _loading) return;

    setState(() => _loading = true);

    final email = _emailCtrl.text.trim();
    final password = _passCtrl.text;

    if (email.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Enter email')));
      setState(() => _loading = false);
      return;
    }
    if (password.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Enter password')));
      setState(() => _loading = false);
      return;
    }

    try {
      await _auth.login(email, password);
      await _startCollapseAnimation(initialLeftWidth);
      if (!mounted) return;
      Navigator.of(context).pushReplacement(PageRouteBuilder(
        pageBuilder: (context, a1, a2) => const HomeDesktopScreen(skipSidebarEntranceAnimation: true),
        transitionDuration: Duration.zero,
        reverseTransitionDuration: Duration.zero,
      ));
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(userFriendlyError(e))));
      setState(() => _isAnimating = false);
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _performSignupFlow(double initialLeftWidth) async {
    if (_isAnimating || _loading) return;

    final email = _signupEmailCtrl.text.trim();
    final phone = _signupPhoneCtrl.text.trim();
    final pass = _signupPassCtrl.text;
    final confirm = _signupConfirmCtrl.text;

    if (email.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Enter email')));
      return;
    }
    if (phone.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Enter phone number')));
      return;
    }
    if (pass.length < 6) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Password must be at least 6 characters')));
      return;
    }
    if (pass != confirm) {
      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Passwords do not match')));
      return;
    }

    setState(() => _loading = true);

    try {
      await _auth.register(
        email: email,
        phoneNumber: phone,
        password: pass,
        district: _signupDistrict,
      );
      await _startCollapseAnimation(initialLeftWidth);
      if (!mounted) return;
      Navigator.of(context).pushReplacement(PageRouteBuilder(
        pageBuilder: (context, a1, a2) => const HomeDesktopScreen(skipSidebarEntranceAnimation: true),
        transitionDuration: Duration.zero,
        reverseTransitionDuration: Duration.zero,
      ));
    } catch (e) {
      if (!mounted) return;
      ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(userFriendlyError(e))));
      setState(() => _isAnimating = false);
    } finally {
      if (mounted) setState(() => _loading = false);
    }
  }

  Future<void> _openForgotPasswordDialog() async {
    final emailCtrl = TextEditingController(text: _emailCtrl.text.trim());
    bool submitting = false;

    await showDialog<void>(
      context: context,
      builder: (ctx) {
        return StatefulBuilder(
          builder: (ctx, setDialog) {
            return AlertDialog(
              title: const Text('Forgot Password'),
              content: SizedBox(
                width: 360,
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text("Enter your email and we'll send reset instructions."),
                    const SizedBox(height: 12),
                    TextField(
                      controller: emailCtrl,
                      decoration: InputDecoration(
                        prefixIcon: const Icon(Icons.email),
                        labelText: 'Email',
                        border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
                      ),
                      keyboardType: TextInputType.emailAddress,
                    ),
                  ],
                ),
              ),
              actions: [
                TextButton(onPressed: () => Navigator.of(ctx).pop(), child: const Text('Cancel')),
                ElevatedButton(
                  onPressed: submitting
                      ? null
                      : () async {
                          final email = emailCtrl.text.trim();
                          if (email.isEmpty) return;
                          setDialog(() => submitting = true);
                          try {
                            await _auth.forgotPassword(email);
                          } catch (_) {
                            // safe-degrade
                          }
                          if (!ctx.mounted) return;
                          Navigator.of(ctx).pop();
                          if (!mounted) return;
                          ScaffoldMessenger.of(context).showSnackBar(
                            const SnackBar(
                              content: Text("If that email is registered, we've sent reset instructions."),
                              duration: Duration(seconds: 4),
                            ),
                          );
                        },
                  child: submitting
                      ? const SizedBox(width: 16, height: 16, child: CircularProgressIndicator(strokeWidth: 2))
                      : const Text('Send reset link'),
                ),
              ],
            );
          },
        );
      },
    );

    emailCtrl.dispose();
  }

  Widget _buildLoginFields(double safeInitialWidth) {
    return Column(
      key: const ValueKey('login'),
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        const Text('Sign In', style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold), textAlign: TextAlign.center),
        const SizedBox(height: 6),
        const Text('Please enter your details to continue', textAlign: TextAlign.center, style: TextStyle(color: Colors.black54)),
        const SizedBox(height: 22),
        TextField(
          controller: _emailCtrl,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.email),
            labelText: 'Email Address',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
        ),
        const SizedBox(height: 12),
        TextField(
          controller: _passCtrl,
          obscureText: true,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.lock),
            labelText: 'Password',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
        ),
        const SizedBox(height: 12),
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: [
            Row(children: [
              Checkbox(value: true, onChanged: (_) {}),
              const Text('Remember me'),
            ]),
            TextButton(onPressed: _openForgotPasswordDialog, child: const Text('Forgot Password?')),
          ],
        ),
        const SizedBox(height: 8),
        SizedBox(
          height: 50,
          child: ElevatedButton(
            onPressed: (_isAnimating || _loading) ? null : () => _performLoginFlow(safeInitialWidth),
            style: ElevatedButton.styleFrom(shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8))),
            child: (_isAnimating || _loading)
                ? const SizedBox(width: 20, height: 20, child: CircularProgressIndicator(color: Colors.white, strokeWidth: 2))
                : const Text('Sign In', style: TextStyle(fontSize: 16)),
          ),
        ),
        const SizedBox(height: 12),
        Wrap(
          alignment: WrapAlignment.spaceBetween,
          children: [
            TextButton(
              onPressed: () => setState(() => _isSignupMode = true),
              child: const Text("Don't have an account? Register"),
            ),
            TextButton(onPressed: () {}, child: const Text('Contact support')),
            TextButton(
              onPressed: () {
                AuthGuard.setGuest(true);
                Navigator.of(context).pushAndRemoveUntil(
                  MaterialPageRoute(builder: (_) => const HomeDesktopScreen(skipSidebarEntranceAnimation: true)),
                  (route) => false,
                );
              },
              child: const Text('Continue as Guest'),
            ),
          ],
        ),
      ],
    );
  }

  Widget _buildSignupFields(double safeInitialWidth) {
    return Column(
      key: const ValueKey('signup'),
      mainAxisSize: MainAxisSize.min,
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        const Text('Create Account', style: TextStyle(fontSize: 24, fontWeight: FontWeight.bold), textAlign: TextAlign.center),
        const SizedBox(height: 6),
        const Text('Fill in your details to get started', textAlign: TextAlign.center, style: TextStyle(color: Colors.black54)),
        const SizedBox(height: 22),
        TextField(
          controller: _signupEmailCtrl,
          keyboardType: TextInputType.emailAddress,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.email),
            labelText: 'Email Address',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
        ),
        const SizedBox(height: 12),
        TextField(
          controller: _signupPhoneCtrl,
          keyboardType: TextInputType.phone,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.phone),
            labelText: 'Phone Number',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
        ),
        const SizedBox(height: 12),
        DropdownButtonFormField<String>(
          value: _signupDistrict,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.location_on),
            labelText: 'District (optional)',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
          items: _districts.map((d) => DropdownMenuItem(value: d, child: Text(d))).toList(),
          onChanged: (v) => setState(() => _signupDistrict = v),
        ),
        const SizedBox(height: 12),
        TextField(
          controller: _signupPassCtrl,
          obscureText: true,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.lock),
            labelText: 'Password',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
        ),
        const SizedBox(height: 12),
        TextField(
          controller: _signupConfirmCtrl,
          obscureText: true,
          decoration: InputDecoration(
            prefixIcon: const Icon(Icons.lock_outline),
            labelText: 'Confirm Password',
            border: OutlineInputBorder(borderRadius: BorderRadius.circular(8)),
          ),
        ),
        const SizedBox(height: 16),
        SizedBox(
          height: 50,
          child: ElevatedButton(
            onPressed: (_isAnimating || _loading) ? null : () => _performSignupFlow(safeInitialWidth),
            style: ElevatedButton.styleFrom(shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8))),
            child: (_isAnimating || _loading)
                ? const SizedBox(width: 20, height: 20, child: CircularProgressIndicator(color: Colors.white, strokeWidth: 2))
                : const Text('Create Account', style: TextStyle(fontSize: 16)),
          ),
        ),
        const SizedBox(height: 12),
        Center(
          child: TextButton(
            onPressed: () => setState(() => _isSignupMode = false),
            child: const Text('Already have an account? Sign in'),
          ),
        ),
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    final screenW = MediaQuery.of(context).size.width;
    final double safeInitialWidth = (screenW * 0.45).clamp(360.0, screenW * 0.65);
    final bool animAvailable = _controller != null && _leftWidthAnim != null;
    final Listenable animation = _controller ?? AlwaysStoppedAnimation(0.0);

    return Scaffold(
      body: SafeArea(
        child: AnimatedBuilder(
          animation: animation,
          builder: (context, child) {
            final leftWidth = animAvailable ? _leftWidthAnim!.value : safeInitialWidth;
            final leftTextOpacity = animAvailable && _leftTextOpacityAnim != null ? _leftTextOpacityAnim!.value : 1.0;
            final formOpacity = animAvailable && _formOpacityAnim != null ? _formOpacityAnim!.value : 1.0;
            final formOffset = animAvailable && _formOffsetAnim != null ? _formOffsetAnim!.value : 0.0;

            return Row(
              children: [
                Container(
                  width: leftWidth,
                  height: double.infinity,
                  decoration: AppDecoration.blueGradient,
                  padding: const EdgeInsets.symmetric(horizontal: 36, vertical: 28),
                  child: Opacity(
                    opacity: leftTextOpacity,
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        const SizedBox(height: 4),
                        const Text('EVENTIFY', style: TextStyle(color: Colors.white, fontWeight: FontWeight.w800, fontSize: 22)),
                        const Spacer(),
                        Text(
                          _isSignupMode ? 'Join Eventify!' : 'Welcome Back!',
                          style: const TextStyle(color: Colors.white, fontSize: 34, fontWeight: FontWeight.bold),
                        ),
                        const SizedBox(height: 12),
                        Text(
                          _isSignupMode
                              ? 'Create your account to discover events, book tickets, and connect with your community.'
                              : 'Sign in to access your dashboard, manage events, and stay connected.',
                          style: const TextStyle(color: Colors.white70, fontSize: 14),
                        ),
                        const Spacer(flex: 2),
                        Opacity(
                          opacity: leftWidth > (_collapsedWidth + 8) ? 1.0 : 0.0,
                          child: const Padding(
                            padding: EdgeInsets.only(bottom: 12.0),
                            child: Text('© Eventify', style: TextStyle(color: Colors.white54)),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
                Expanded(
                  child: Transform.translate(
                    offset: Offset(formOffset, 0),
                    child: Opacity(
                      opacity: formOpacity,
                      child: Container(
                        color: Colors.white,
                        padding: const EdgeInsets.symmetric(horizontal: 48, vertical: 36),
                        child: Center(
                          child: SingleChildScrollView(
                            child: ConstrainedBox(
                              constraints: const BoxConstraints(maxWidth: 520),
                              child: Card(
                                elevation: 0,
                                shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
                                child: Padding(
                                  padding: const EdgeInsets.symmetric(horizontal: 28.0, vertical: 28.0),
                                  child: AnimatedSwitcher(
                                    duration: const Duration(milliseconds: 260),
                                    child: _isSignupMode
                                        ? _buildSignupFields(safeInitialWidth)
                                        : _buildLoginFields(safeInitialWidth),
                                  ),
                                ),
                              ),
                            ),
                          ),
                        ),
                      ),
                    ),
                  ),
                ),
              ],
            );
          },
        ),
      ),
    );
  }
}