import 'package:cb_prestige_qr/core/utils/MainShell.dart';
import 'package:flutter/material.dart';
import 'package:local_auth/local_auth.dart';

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

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

enum _SupportState { unknown, supported, unsupported }

class _LoginPageState extends State<LoginPage> {
  final _formKey = GlobalKey<FormState>();
  final _usernameController = TextEditingController();
  final _passwordController = TextEditingController();
  final LocalAuthentication auth = LocalAuthentication();
  bool? _canCheckBiometric;
  List<BiometricType>? _availableBiometrics;
  String _authorized = "Not Authorized";
  bool _isAuthenticating = false;
  bool _isSigningIn = false;
  _SupportState _supportState = _SupportState.unknown;

  var _obscurePassword = true;
  
  @override
  void initState(){
    super.initState();
    auth.isDeviceSupported().then(
          (bool isSupported) => setState(
            () => _supportState = isSupported
            ? _SupportState.supported
            : _SupportState.unsupported,
      ),
    );
  }

  @override
  void dispose() {
    _usernameController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  Future<void> _submit() async {
    final form = _formKey.currentState;
    if (form == null || !form.validate()) return;

    setState(() {
      _isSigningIn = true;
    });

    await Future<void>.delayed(const Duration(seconds: 2));

    if (!mounted) return;

    Navigator.of(context).pushReplacement(
      MaterialPageRoute(builder: (_) => const MainShell()),
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;

    return Scaffold(
      body: Container(
        decoration: const BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topCenter,
            end: Alignment.bottomCenter,
            colors: [
              Color(0xff17181c),
              Color(0xff25262b),
              Color(0xff2c2d33),
            ],
          ),
        ),
        child: SafeArea(
          child: Center(
            child: SingleChildScrollView(
              padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 20),
              child: ConstrainedBox(
                constraints: const BoxConstraints(maxWidth: 440),
                child: Container(
                  padding: const EdgeInsets.all(24),
                  decoration: BoxDecoration(
                    color: const Color(0xff1d1e23).withOpacity(0.92),
                    borderRadius: BorderRadius.circular(28),
                    border: Border.all(color: Colors.white.withOpacity(0.08)),
                    boxShadow: [
                      BoxShadow(
                        color: Colors.black.withOpacity(0.28),
                        blurRadius: 28,
                        offset: const Offset(0, 18),
                      ),
                    ],
                  ),
                  child: Form(
                    key: _formKey,
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        Row(
                          children: [
                            Container(
                              height: 56,
                              width: 56,
                              decoration: BoxDecoration(
                                color: colorScheme.primary.withOpacity(0.16),
                                borderRadius: BorderRadius.circular(18),
                              ),
                              child: const Icon(
                                Icons.lock_person_rounded,
                                color: Colors.white,
                                size: 30,
                              ),
                            ),
                            const SizedBox(width: 16),
                            Expanded(
                              child: Column(
                                crossAxisAlignment: CrossAxisAlignment.start,
                                children: [
                                  Text(
                                    'Secure Login',
                                    style: theme.textTheme.headlineSmall
                                        ?.copyWith(
                                          fontWeight: FontWeight.w700,
                                          color: Colors.white,
                                        ),
                                  ),
                                  const SizedBox(height: 4),
                                  Text(
                                    'Use your username and password to continue.',
                                    style: theme.textTheme.bodyMedium?.copyWith(
                                      color: Colors.white70,
                                      height: 1.35,
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          ],
                        ),
                        const SizedBox(height: 28),
                        Container(
                          width: double.infinity,
                          padding: const EdgeInsets.all(18),
                          decoration: BoxDecoration(
                            color: Colors.white.withOpacity(0.04),
                            borderRadius: BorderRadius.circular(20),
                            border: Border.all(
                              color: Colors.white.withOpacity(0.06),
                            ),
                          ),
                          child: Row(
                            children: [
                              ClipRRect(
                                borderRadius: BorderRadius.circular(14),
                                child: Image.asset(
                                  'assets/images/logo_white.png',
                                  height: 48,
                                  width: 48,
                                  fit: BoxFit.cover,
                                ),
                              ),
                              const SizedBox(width: 14),
                              Expanded(
                                child: Column(
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  children: [
                                    Text(
                                      'CB Prestige Banking',
                                      style: theme.textTheme.titleMedium
                                          ?.copyWith(
                                            color: Colors.white,
                                            fontWeight: FontWeight.w600,
                                          ),
                                    ),
                                    const SizedBox(height: 2),
                                    Text(
                                      'Sign in to access your QR dashboard.',
                                      style: theme.textTheme.bodySmall
                                          ?.copyWith(color: Colors.white60),
                                    ),
                                  ],
                                ),
                              ),
                            ],
                          ),
                        ),
                        const SizedBox(height: 28),
                        _AuthTextField(
                          controller: _usernameController,
                          label: 'Username',
                          hintText: 'Enter your username',
                          keyboardType: TextInputType.text,
                          prefixIcon: Icons.person_rounded,
                          validator: (value) {
                            final username = value?.trim() ?? '';
                            if (username.isEmpty) {
                              return 'Username is required';
                            }
                            if (username.length < 3) {
                              return 'Username must be at least 3 characters';
                            }
                            return null;
                          },
                        ),
                        const SizedBox(height: 16),
                        _AuthTextField(
                          controller: _passwordController,
                          label: 'Password',
                          hintText: 'Enter your password',
                          prefixIcon: Icons.lock_rounded,
                          obscureText: _obscurePassword,
                          validator: (value) {
                            final password = value ?? '';
                            if (password.isEmpty) {
                              return 'Password is required';
                            }
                            if (password.length < 6) {
                              return 'Password must be at least 6 characters';
                            }
                            return null;
                          },
                          suffixIcon: IconButton(
                            onPressed: () {
                              setState(() {
                                _obscurePassword = !_obscurePassword;
                              });
                            },
                            icon: Icon(
                              _obscurePassword
                                  ? Icons.visibility_off_rounded
                                  : Icons.visibility_rounded,
                              color: Colors.white70,
                            ),
                          ),
                        ),
                        const SizedBox(height: 12),
                        Align(
                          alignment: Alignment.centerRight,
                          child: TextButton(
                            onPressed: () {},
                            child: const Text('Forgot password?'),
                          ),
                        ),
                        const SizedBox(height: 24),
                        SizedBox(
                          width: double.infinity,
                          child: FilledButton(
                            onPressed: _isSigningIn ? null : _submit,
                            style: FilledButton.styleFrom(
                              backgroundColor: colorScheme.primary,
                              foregroundColor: Colors.white,
                              padding: const EdgeInsets.symmetric(vertical: 16),
                              shape: RoundedRectangleBorder(
                                borderRadius: BorderRadius.circular(18),
                              ),
                            ),
                            child: _isSigningIn
                                ? const SizedBox(
                                    height: 20,
                                    width: 20,
                                    child: CircularProgressIndicator(
                                      strokeWidth: 2.4,
                                      valueColor: AlwaysStoppedAnimation<Color>(
                                        Colors.white,
                                      ),
                                    ),
                                  )
                                : const Text(
                                    'Sign In',
                                    style: TextStyle(
                                      fontSize: 16,
                                      fontWeight: FontWeight.w600,
                                    ),
                                  ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class _AuthTextField extends StatelessWidget {
  const _AuthTextField({
    required this.controller,
    required this.label,
    required this.hintText,
    required this.prefixIcon,
    required this.validator,
    this.keyboardType,
    this.obscureText = false,
    this.suffixIcon,
  });

  final TextEditingController controller;
  final String label;
  final String hintText;
  final IconData prefixIcon;
  final String? Function(String?) validator;
  final TextInputType? keyboardType;
  final bool obscureText;
  final Widget? suffixIcon;

  @override
  Widget build(BuildContext context) {
    return TextFormField(
      controller: controller,
      keyboardType: keyboardType,
      obscureText: obscureText,
      validator: validator,
      style: const TextStyle(color: Colors.white),
      decoration: InputDecoration(
        labelText: label,
        hintText: hintText,
        prefixIcon: Icon(prefixIcon),
        suffixIcon: suffixIcon,
      ),
    );
  }
}