import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../providers/auth_provider.dart';
import 'home_screen.dart';

/// Login screen for user authentication
///
/// Provides input fields for student ID, EC password, and UAAP password
/// Integrates with AuthProvider for authentication
class LoginScreen extends StatefulWidget {
  const LoginScreen({super.key});

  @override
  State<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final _formKey = GlobalKey<FormState>();
  final _userIdController = TextEditingController();
  final _ecPasswordController = TextEditingController();
  final _passwordController = TextEditingController();

  bool _obscureEcPassword = true;
  bool _obscurePassword = true;

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

  Future<void> _handleLogin() async {
    if (!_formKey.currentState!.validate()) {
      return;
    }

    final authProvider = Provider.of<AuthProvider>(context, listen: false);

    final success = await authProvider.login(
      userId: _userIdController.text.trim(),
      ecPassword: _ecPasswordController.text,
      password: _passwordController.text,
    );

    if (!mounted) return;

    if (success) {
      // Navigate to home screen
      Navigator.of(context).pushReplacement(
        MaterialPageRoute(builder: (context) => const HomeScreen()),
      );
    } else {
      // Show error message
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(authProvider.errorMessage ?? '登录失败'),
          backgroundColor: Theme.of(context).colorScheme.error,
        ),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.all(24.0),
            child: Form(
              key: _formKey,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  // App logo/title
                  Icon(
                    Icons.school,
                    size: 80,
                    color: Theme.of(context).colorScheme.primary,
                  ),
                  const SizedBox(height: 16),
                  Text(
                    '自动评教系统',
                    style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                      fontWeight: FontWeight.bold,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 8),
                  Text(
                    '安徽财经大学',
                    style: Theme.of(context).textTheme.bodyLarge?.copyWith(
                      color: Theme.of(context).colorScheme.onSurfaceVariant,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 48),

                  // Student ID field
                  TextFormField(
                    controller: _userIdController,
                    decoration: const InputDecoration(
                      labelText: '学号',
                      hintText: '请输入学号',
                      prefixIcon: Icon(Icons.person),
                    ),
                    keyboardType: TextInputType.number,
                    validator: (value) {
                      if (value == null || value.trim().isEmpty) {
                        return '请输入学号';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 16),

                  // EC password field
                  TextFormField(
                    controller: _ecPasswordController,
                    decoration: InputDecoration(
                      labelText: 'EC密码',
                      hintText: '请输入EC系统密码',
                      prefixIcon: const Icon(Icons.lock),
                      suffixIcon: IconButton(
                        icon: Icon(
                          _obscureEcPassword
                              ? Icons.visibility_off
                              : Icons.visibility,
                        ),
                        onPressed: () {
                          setState(() {
                            _obscureEcPassword = !_obscureEcPassword;
                          });
                        },
                      ),
                    ),
                    obscureText: _obscureEcPassword,
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return '请输入EC密码';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 16),

                  // UAAP password field
                  TextFormField(
                    controller: _passwordController,
                    decoration: InputDecoration(
                      labelText: 'UAAP密码',
                      hintText: '请输入UAAP系统密码',
                      prefixIcon: const Icon(Icons.vpn_key),
                      suffixIcon: IconButton(
                        icon: Icon(
                          _obscurePassword
                              ? Icons.visibility_off
                              : Icons.visibility,
                        ),
                        onPressed: () {
                          setState(() {
                            _obscurePassword = !_obscurePassword;
                          });
                        },
                      ),
                    ),
                    obscureText: _obscurePassword,
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return '请输入UAAP密码';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 32),

                  // Login button
                  Consumer<AuthProvider>(
                    builder: (context, authProvider, child) {
                      final isLoading = authProvider.state == AuthState.loading;

                      return ElevatedButton(
                        onPressed: isLoading ? null : _handleLogin,
                        style: ElevatedButton.styleFrom(
                          padding: const EdgeInsets.symmetric(vertical: 16),
                          backgroundColor: Theme.of(
                            context,
                          ).colorScheme.primary,
                          foregroundColor: Theme.of(
                            context,
                          ).colorScheme.onPrimary,
                        ),
                        child: isLoading
                            ? const SizedBox(
                                height: 20,
                                width: 20,
                                child: CircularProgressIndicator(
                                  strokeWidth: 2,
                                ),
                              )
                            : const Text('登录', style: TextStyle(fontSize: 16)),
                      );
                    },
                  ),
                  const SizedBox(height: 16),

                  // Help text
                  Text(
                    '首次登录需要输入EC和UAAP系统密码\n登录信息将被安全加密存储',
                    style: Theme.of(context).textTheme.bodySmall?.copyWith(
                      color: Theme.of(context).colorScheme.onSurfaceVariant,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 32),

                  // Signature
                  Column(
                    children: [
                      Text(
                        '❤ Created By LoveACE Team',
                        style: Theme.of(context).textTheme.bodySmall?.copyWith(
                          color: Theme.of(
                            context,
                          ).colorScheme.onSurfaceVariant.withOpacity(0.6),
                        ),
                        textAlign: TextAlign.center,
                      ),
                      const SizedBox(height: 4),
                      Text(
                        '🌧 Powered By Sibuxiangx & Flutter',
                        style: Theme.of(context).textTheme.bodySmall?.copyWith(
                          color: Theme.of(
                            context,
                          ).colorScheme.onSurfaceVariant.withOpacity(0.6),
                        ),
                        textAlign: TextAlign.center,
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}