import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:provider/provider.dart';
import '../../../shared/services/cache_service.dart';
import '../services/auth_provider.dart';

/// 登录页面
///
/// 支持表单校验、密码可见切换、记住用户名（通过 CacheService 持久化）、加载态。
class LoginPage extends StatefulWidget {
  const LoginPage({super.key});

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

class _LoginPageState extends State<LoginPage> {
  static const String _kRememberKey = 'login:remember_username';

  final _formKey = GlobalKey<FormState>();
  final _usernameController = TextEditingController();
  final _passwordController = TextEditingController();
  final _cache = CacheService();

  bool _obscurePassword = true;
  bool _rememberUsername = true;
  bool _restored = false;

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

  /// 从本地缓存恢复上次记住的用户名
  Future<void> _restoreRememberedUsername() async {
    final saved = await _cache.get<String>(_kRememberKey, box: 'auth');
    if (saved != null && saved.isNotEmpty && mounted) {
      setState(() {
        _usernameController.text = saved;
        _restored = true;
      });
    }
  }

  /// 持久化/清除记住的用户名
  Future<void> _persistRememberedUsername(String username) async {
    if (_rememberUsername) {
      await _cache.put(_kRememberKey, username, box: 'auth');
    } else {
      await _cache.delete(_kRememberKey, box: 'auth');
    }
  }

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

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

    final username = _usernameController.text.trim();
    final authProvider = Provider.of<AuthProvider>(context, listen: false);
    final success = await authProvider.login(
      username: username,
      password: _passwordController.text,
    );

    if (success && mounted) {
      // 登录成功：按勾选状态持久化用户名
      await _persistRememberedUsername(username);
      // 登录成功后路由由 AuthGuard 自动处理
      GoRouter.of(context).go('/main');
    } else if (mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(authProvider.errorMessage ?? '登录失败'),
          backgroundColor: Colors.red,
        ),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.all(32),
            child: Form(
              key: _formKey,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  // Logo 和应用名
                  const Icon(
                    Icons.water_drop,
                    size: 80,
                    color: Color(0xFF1976D2),
                  ),
                  const SizedBox(height: 16),
                  const Text(
                    '供水管理系统',
                    textAlign: TextAlign.center,
                    style: TextStyle(
                      fontSize: 24,
                      fontWeight: FontWeight.bold,
                      color: Color(0xFF1976D2),
                    ),
                  ),
                  const SizedBox(height: 8),
                  Text(
                    '供水 · 巡检 · 营收',
                    textAlign: TextAlign.center,
                    style: TextStyle(
                      fontSize: 14,
                      color: Colors.grey[600],
                    ),
                  ),
                  const SizedBox(height: 48),

                  // 用户名输入
                  TextFormField(
                    controller: _usernameController,
                    decoration: const InputDecoration(
                      labelText: '用户名',
                      prefixIcon: Icon(Icons.person),
                      hintText: '请输入用户名',
                    ),
                    validator: (value) {
                      if (value == null || value.trim().isEmpty) {
                        return '请输入用户名';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 16),

                  // 密码输入
                  TextFormField(
                    controller: _passwordController,
                    decoration: InputDecoration(
                      labelText: '密码',
                      prefixIcon: const Icon(Icons.lock),
                      hintText: '请输入密码',
                      suffixIcon: IconButton(
                        icon: Icon(
                          _obscurePassword ? Icons.visibility_off : Icons.visibility,
                        ),
                        onPressed: () {
                          setState(() {
                            _obscurePassword = !_obscurePassword;
                          });
                        },
                      ),
                    ),
                    obscureText: _obscurePassword,
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return '请输入密码';
                      }
                      if (value.length < 6) {
                        return '密码长度不能少于6位';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 12),

                  // 记住用户名
                  Row(
                    children: [
                      Checkbox(
                        value: _rememberUsername,
                        onChanged: (v) => setState(() => _rememberUsername = v ?? false),
                      ),
                      const Text('记住用户名'),
                    ],
                  ),
                  const SizedBox(height: 20),

                  // 登录按钮
                  Consumer<AuthProvider>(
                    builder: (context, auth, child) {
                      return ElevatedButton(
                        onPressed: auth.isLoading ? null : _handleLogin,
                        child: auth.isLoading
                            ? const SizedBox(
                                height: 20,
                                width: 20,
                                child: CircularProgressIndicator(
                                  strokeWidth: 2,
                                  color: Colors.white,
                                ),
                              )
                            : const Text(
                                '登 录',
                                style: TextStyle(fontSize: 16),
                              ),
                      );
                    },
                  ),
                  const SizedBox(height: 16),

                  // 版本信息
                  Text(
                    'v1.0.0',
                    textAlign: TextAlign.center,
                    style: TextStyle(color: Colors.grey[400], fontSize: 12),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}