import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:flutter_svg/flutter_svg.dart';
import 'package:go_router/go_router.dart';
import '../../../../core/theme/app_colors.dart';
import '../../data/providers/auth_provider.dart';
import 'package:it0_app/l10n/app_localizations.dart';

enum _LoginMode { password, otp }

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

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

class _LoginPageState extends ConsumerState<LoginPage> {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  final _phoneController = TextEditingController();
  final _otpController = TextEditingController();

  _LoginMode _mode = _LoginMode.password;
  int _smsCooldown = 0;
  bool _smsSending = false;
  Timer? _cooldownTimer;

  @override
  void dispose() {
    _emailController.dispose();
    _passwordController.dispose();
    _phoneController.dispose();
    _otpController.dispose();
    _cooldownTimer?.cancel();
    super.dispose();
  }

  Future<void> _sendSmsCode() async {
    final phone = _phoneController.text.trim();
    if (phone.isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text(AppLocalizations.of(context).enterPhoneFirstError)),
      );
      return;
    }
    setState(() => _smsSending = true);
    try {
      await ref.read(authStateProvider.notifier).sendSmsCode(phone);
      setState(() => _smsCooldown = 60);
      _cooldownTimer = Timer.periodic(const Duration(seconds: 1), (t) {
        setState(() {
          if (_smsCooldown <= 1) {
            _smsCooldown = 0;
            t.cancel();
          } else {
            _smsCooldown--;
          }
        });
      });
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(e.toString())),
        );
      }
    } finally {
      if (mounted) setState(() => _smsSending = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final authState = ref.watch(authStateProvider);

    return Scaffold(
      backgroundColor: AppColors.background,
      body: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.symmetric(horizontal: 32, vertical: 48),
          child: Form(
            key: _formKey,
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 360),
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  SvgPicture.asset('assets/icons/logo.svg', width: 96, height: 96),
                  const SizedBox(height: 12),
                  Text(
                    AppLocalizations.of(context).appTitle,
                    style: const TextStyle(
                      color: AppColors.textPrimary,
                      fontSize: 28,
                      fontWeight: FontWeight.bold,
                      letterSpacing: 2,
                    ),
                  ),
                  const SizedBox(height: 4),
                  Text(
                    AppLocalizations.of(context).appSubtitle,
                    style: const TextStyle(color: AppColors.textSecondary, fontSize: 14),
                  ),
                  const SizedBox(height: 32),

                  // Login mode toggle
                  Container(
                    decoration: BoxDecoration(
                      color: AppColors.surface,
                      borderRadius: BorderRadius.circular(8),
                      border: Border.all(color: AppColors.surfaceLight),
                    ),
                    child: Row(
                      children: [
                        Expanded(child: _modeButton(AppLocalizations.of(context).loginPasswordTab, _LoginMode.password)),
                        Expanded(child: _modeButton(AppLocalizations.of(context).loginOtpTab, _LoginMode.otp)),
                      ],
                    ),
                  ),
                  const SizedBox(height: 24),

                  if (_mode == _LoginMode.password) ...[
                    TextFormField(
                      controller: _emailController,
                      keyboardType: TextInputType.text,
                      decoration: const InputDecoration(
                        labelText: '邮箱 / 手机号',
                        hintText: '请输入邮箱或手机号',
                        prefixIcon: Icon(Icons.person_outline),
                      ),
                      validator: (v) {
                        if (v == null || v.isEmpty) return '请输入邮箱或手机号';
                        return null;
                      },
                    ),
                    const SizedBox(height: 16),
                    TextFormField(
                      controller: _passwordController,
                      obscureText: true,
                      decoration: InputDecoration(
                        labelText: AppLocalizations.of(context).passwordLabel,
                        prefixIcon: const Icon(Icons.lock_outline),
                      ),
                      validator: (v) => (v == null || v.isEmpty) ? '请输入密码' : null,
                      onFieldSubmitted: (_) => _handlePasswordLogin(),
                    ),
                  ] else ...[
                    TextFormField(
                      controller: _phoneController,
                      keyboardType: TextInputType.phone,
                      decoration: InputDecoration(
                        labelText: AppLocalizations.of(context).phoneLabel,
                        hintText: AppLocalizations.of(context).phoneHint,
                        prefixIcon: const Icon(Icons.phone_outlined),
                      ),
                      validator: (v) => (v == null || v.isEmpty) ? '请输入手机号' : null,
                    ),
                    const SizedBox(height: 16),
                    Row(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Expanded(
                          child: TextFormField(
                            controller: _otpController,
                            keyboardType: TextInputType.number,
                            maxLength: 6,
                            decoration: InputDecoration(
                              labelText: AppLocalizations.of(context).otpLabel,
                              hintText: AppLocalizations.of(context).otpHint,
                              prefixIcon: const Icon(Icons.sms_outlined),
                              counterText: '',
                            ),
                            validator: (v) => (v == null || v.isEmpty) ? '请输入验证码' : null,
                            onFieldSubmitted: (_) => _handleOtpLogin(),
                          ),
                        ),
                        const SizedBox(width: 8),
                        SizedBox(
                          height: 56,
                          child: OutlinedButton(
                            onPressed: (_smsSending || _smsCooldown > 0) ? null : _sendSmsCode,
                            child: Text(
                              _smsSending
                                  ? AppLocalizations.of(context).sendingLabel
                                  : _smsCooldown > 0
                                      ? '${_smsCooldown}s'
                                      : AppLocalizations.of(context).getOtpButton,
                              style: const TextStyle(fontSize: 13),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ],

                  if (authState.error != null) ...[
                    const SizedBox(height: 16),
                    Container(
                      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
                      decoration: BoxDecoration(
                        color: AppColors.error.withAlpha(25),
                        borderRadius: BorderRadius.circular(8),
                      ),
                      child: Row(
                        children: [
                          const Icon(Icons.error_outline, color: AppColors.error, size: 18),
                          const SizedBox(width: 8),
                          Expanded(
                            child: Text(
                              authState.error!,
                              style: const TextStyle(color: AppColors.error, fontSize: 13),
                            ),
                          ),
                        ],
                      ),
                    ),
                  ],
                  const SizedBox(height: 24),
                  SizedBox(
                    width: double.infinity,
                    height: 48,
                    child: FilledButton(
                      onPressed: authState.isLoading
                          ? null
                          : (_mode == _LoginMode.password
                              ? _handlePasswordLogin
                              : _handleOtpLogin),
                      child: authState.isLoading
                          ? const SizedBox(
                              height: 20,
                              width: 20,
                              child: CircularProgressIndicator(
                                  strokeWidth: 2, color: Colors.white),
                            )
                          : Text(AppLocalizations.of(context).loginButton, style: const TextStyle(fontSize: 16)),
                    ),
                  ),
                  const SizedBox(height: 32),
                  Text(
                    AppLocalizations.of(context).accountCreationNote,
                    style: const TextStyle(color: AppColors.textMuted, fontSize: 12),
                    textAlign: TextAlign.center,
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  Widget _modeButton(String label, _LoginMode mode) {
    final selected = _mode == mode;
    return GestureDetector(
      onTap: () => setState(() => _mode = mode),
      child: Container(
        padding: const EdgeInsets.symmetric(vertical: 10),
        decoration: BoxDecoration(
          color: selected ? AppColors.primary : Colors.transparent,
          borderRadius: BorderRadius.circular(7),
        ),
        child: Text(
          label,
          textAlign: TextAlign.center,
          style: TextStyle(
            fontSize: 14,
            fontWeight: FontWeight.w500,
            color: selected ? Colors.white : AppColors.textSecondary,
          ),
        ),
      ),
    );
  }

  Future<void> _handlePasswordLogin() async {
    if (!_formKey.currentState!.validate()) return;
    final success = await ref.read(authStateProvider.notifier).login(
          _emailController.text.trim(),
          _passwordController.text,
        );
    if (success && mounted) context.go('/home');
  }

  Future<void> _handleOtpLogin() async {
    if (!_formKey.currentState!.validate()) return;
    final success = await ref.read(authStateProvider.notifier).loginWithOtp(
          _phoneController.text.trim(),
          _otpController.text.trim(),
        );
    if (success && mounted) context.go('/home');
  }
}