import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

import '../services/auth_api.dart';
import '../services/call_service.dart';
import '../services/im_service.dart';
import '../theme.dart';
import 'home_screen.dart';

/// 登录页：工号 + 密码，登录中按钮转菊花，失败在按钮下方红字提示。
class LoginScreen extends StatefulWidget {
  const LoginScreen({super.key});

  /// 本地保存登录凭证的键（自动登录用）
  static const String keyUserID = 'login_userID';
  static const String keyToken = 'login_token';
  static const String keyNickname = 'login_nickname';

  /// 保存登录凭证
  static Future<void> saveCredential(String userID, String token, String nickname) async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString(keyUserID, userID);
    await prefs.setString(keyToken, token);
    await prefs.setString(keyNickname, nickname);
  }

  /// 清除登录凭证（退出登录 / token 失效时）
  static Future<void> clearCredential() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(keyUserID);
    await prefs.remove(keyToken);
    await prefs.remove(keyNickname);
  }

  /// 读取已保存的凭证
  static Future<(String, String)?> readCredential() async {
    final prefs = await SharedPreferences.getInstance();
    final userID = prefs.getString(keyUserID);
    final token = prefs.getString(keyToken);
    if (userID == null || userID.isEmpty || token == null || token.isEmpty) return null;
    return (userID, token);
  }

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

class _LoginScreenState extends State<LoginScreen> {
  final TextEditingController _idCtrl = TextEditingController();
  final TextEditingController _pwdCtrl = TextEditingController();
  final AuthApi _authApi = AuthApi();

  bool _logging = false;
  String? _error;

  @override
  void dispose() {
    _idCtrl.dispose();
    _pwdCtrl.dispose();
    super.dispose();
  }

  Future<void> _login() async {
    final staffNo = _idCtrl.text.trim();
    final password = _pwdCtrl.text;
    if (staffNo.isEmpty || password.isEmpty) {
      setState(() => _error = '请输入工号和密码');
      return;
    }
    setState(() {
      _logging = true;
      _error = null;
    });
    try {
      // 1. 公司账号登录，拿 OpenIM 的 userID/imToken
      final result = await _authApi.login(
        staffNo: staffNo,
        password: password,
        platformID: IMService.instance.platformID,
      );
      // 2. 登录 OpenIM SDK（服务器连不上时这一步可能长时间不返回，加超时兜底）
      await IMService.instance.login(userID: result.userID, token: result.token).timeout(
        const Duration(seconds: 20),
        onTimeout: () => throw AuthException('连不上消息服务器，请确认手机连着公司内网 WiFi'),
      );
      // 3. 启动通话信令监听
      CallService.instance.start();
      // 4. 存凭证用于下次自动登录
      await LoginScreen.saveCredential(result.userID, result.token, result.nickname);
      if (!mounted) return;
      Navigator.of(context).pushReplacement(
        MaterialPageRoute(builder: (_) => const HomeScreen()),
      );
    } on AuthException catch (e) {
      setState(() => _error = e.message);
    } catch (_) {
      setState(() => _error = '登录出错了，请稍后再试');
    } finally {
      if (mounted) setState(() => _logging = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.pageBg,
      body: SafeArea(
        child: SingleChildScrollView(
          padding: const EdgeInsets.symmetric(horizontal: AppGap.x8),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              const SizedBox(height: 96),
              const Text(
                '畅联',
                textAlign: TextAlign.center,
                style: TextStyle(fontSize: 32, fontWeight: FontWeight.w600, color: AppColors.primary),
              ),
              const SizedBox(height: AppGap.x12),
              _input(_idCtrl, '请输入工号', Icons.person_outline, false),
              const SizedBox(height: AppGap.x4),
              _input(_pwdCtrl, '请输入密码', Icons.lock_outline, true),
              const SizedBox(height: AppGap.x6),
              SizedBox(
                height: 48,
                child: FilledButton(
                  onPressed: _logging ? null : _login,
                  style: FilledButton.styleFrom(
                    backgroundColor: AppColors.primary,
                    shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
                  ),
                  child: _logging
                      ? const SizedBox(
                          width: 20,
                          height: 20,
                          child: CircularProgressIndicator(strokeWidth: 2, color: Colors.white),
                        )
                      : const Text('登录', style: TextStyle(fontSize: AppFont.body)),
                ),
              ),
              if (_error != null) ...[
                const SizedBox(height: AppGap.x3),
                Text(
                  _error!,
                  textAlign: TextAlign.center,
                  style: const TextStyle(fontSize: AppFont.sub, color: AppColors.danger),
                ),
              ],
            ],
          ),
        ),
      ),
    );
  }

  Widget _input(TextEditingController ctrl, String hint, IconData icon, bool obscure) {
    return TextField(
      controller: ctrl,
      obscureText: obscure,
      decoration: InputDecoration(
        hintText: hint,
        hintStyle: const TextStyle(color: AppColors.textSecondary, fontSize: AppFont.body),
        prefixIcon: Icon(icon, color: AppColors.textSecondary),
        filled: true,
        fillColor: AppColors.searchBg,
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide.none,
        ),
        contentPadding: const EdgeInsets.symmetric(vertical: AppGap.x4),
      ),
    );
  }
}