import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart' show defaultTargetPlatform, TargetPlatform;
import 'package:fluwx/fluwx.dart';
import 'package:tobias/tobias.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:sign_in_with_apple/sign_in_with_apple.dart';
import '../../../../app/theme/app_colors.dart';
import '../../../../app/theme/app_typography.dart';
import '../../../../app/theme/app_spacing.dart';
import '../../../../shared/widgets/genex_button.dart';
import '../../../../app/i18n/app_localizations.dart';
import '../../../../core/services/auth_service.dart';

/// A1. 欢迎页 - 品牌展示 + 注册/登录入口
///
/// 平台差异（运行时判断）：
///   Android: 微信 + 支付宝 + Google
///   iOS:     微信 + 支付宝 + Google + Apple
class WelcomePage extends StatefulWidget {
  const WelcomePage({super.key});

  @override
  State<WelcomePage> createState() => _WelcomePageState();
}

class _WelcomePageState extends State<WelcomePage> {
  bool _wechatLoading = false;
  bool _alipayLoading = false;
  bool _googleLoading = false;
  bool _appleLoading = false;

  final _googleSignIn = GoogleSignIn(scopes: ['email', 'profile']);

  @override
  void initState() {
    super.initState();
    // 监听微信授权回调（用户授权后，微信 App 返回 code）
    weChatResponseEventHandler.distinct().listen((res) {
      if (res is WXAuthResp && mounted) {
        _handleWechatAuthResp(res);
      }
    });
  }

  // ── 微信 ─────────────────────────────────────────────────────────────────

  Future<void> _onWechatTap() async {
    final installed = await isWeChatInstalled;
    if (!installed) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(context.t('welcome.wechatNotInstalled'))),
        );
      }
      return;
    }
    setState(() => _wechatLoading = true);
    await sendWeChatAuth(scope: 'snsapi_userinfo', state: 'genex_login');
    // 授权结果通过 weChatResponseEventHandler 异步回调
  }

  Future<void> _handleWechatAuthResp(WXAuthResp resp) async {
    setState(() => _wechatLoading = false);
    if (resp.errCode != 0 || resp.code == null) return;
    try {
      await AuthService.instance.loginByWechat(code: resp.code!);
      if (mounted) Navigator.pushReplacementNamed(context, '/main');
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(context.t('welcome.wechatLoginFailed'))),
        );
      }
    }
  }

  // ── 支付宝 ─────────────────────────────────────────────────────────────────
  // tobias 包使用方法：
  //   isAliPayInstalled() → Future<bool>
  //   aliPay(String orderStr) — 用于支付
  //   但 OAuth 授权用的是 Alipay.authCode(appId, scope) 返回 auth_code
  //
  // tobias v3.x API: aliPayAuth(appId, scope) → Future<Map>
  //   返回 {'resultStatus': '9000', 'memo': '', 'result': '...(含 auth_code)...'}
  //   resultStatus: 9000=成功, 6001=取消, 4000=错误

  Future<void> _onAlipayTap() async {
    final installed = await isAliPayInstalled;
    if (!installed) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(context.t('welcome.alipayNotInstalled'))),
        );
      }
      return;
    }

    setState(() => _alipayLoading = true);
    try {
      // appId 与后端 ALIPAY_APP_ID 一致
      const alipayAppId = String.fromEnvironment('ALIPAY_APP_ID', defaultValue: '');
      final result = await aliPayAuth(alipayAppId, 'auth_user');

      final status = result['resultStatus']?.toString() ?? '';
      if (status != '9000') {
        // 用户取消或错误
        return;
      }

      // 从 result 字符串中解析 auth_code
      // result 格式: "auth_code=AP_xxxxxxxx&scope=auth_user&state=..."
      final resultStr = result['result']?.toString() ?? '';
      final authCode = _parseParam(resultStr, 'auth_code');
      if (authCode == null || authCode.isEmpty) {
        throw Exception('未获取到 auth_code');
      }

      await AuthService.instance.loginByAlipay(authCode: authCode);
      if (mounted) Navigator.pushReplacementNamed(context, '/main');
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(context.t('welcome.alipayLoginFailed'))),
        );
      }
    } finally {
      if (mounted) setState(() => _alipayLoading = false);
    }
  }

  /// 从 URL Query 格式字符串中提取参数值
  String? _parseParam(String str, String key) {
    final uri = Uri(query: str);
    return uri.queryParameters[key];
  }

  // ── Google ─────────────────────────────────────────────────────────────────

  Future<void> _onGoogleTap() async {
    setState(() => _googleLoading = true);
    try {
      final account = await _googleSignIn.signIn();
      if (account == null) return; // 用户取消

      final auth = await account.authentication;
      final idToken = auth.idToken;
      if (idToken == null) throw Exception('未获取到 ID Token');

      await AuthService.instance.loginByGoogle(idToken: idToken);
      if (mounted) Navigator.pushReplacementNamed(context, '/main');
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(context.t('welcome.googleLoginFailed'))),
        );
      }
    } finally {
      if (mounted) setState(() => _googleLoading = false);
    }
  }

  // ── Apple（仅 iOS）────────────────────────────────────────────────────────

  Future<void> _onAppleTap() async {
    setState(() => _appleLoading = true);
    try {
      final credential = await SignInWithApple.getAppleIDCredential(
        scopes: [
          AppleIDAuthorizationScopes.email,
          AppleIDAuthorizationScopes.fullName,
        ],
      );

      final identityToken = credential.identityToken;
      if (identityToken == null) throw Exception('未获取到 Identity Token');

      // 拼接用户显示名（Apple 首次登录时提供，之后为 null）
      final displayName = [
        credential.givenName,
        credential.familyName,
      ].where((s) => s != null && s.isNotEmpty).join(' ');

      await AuthService.instance.loginByApple(
        identityToken: identityToken,
        displayName: displayName.isNotEmpty ? displayName : null,
      );
      if (mounted) Navigator.pushReplacementNamed(context, '/main');
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text(context.t('welcome.appleLoginFailed'))),
        );
      }
    } finally {
      if (mounted) setState(() => _appleLoading = false);
    }
  }

  // ── Build ─────────────────────────────────────────────────────────────────

  @override
  Widget build(BuildContext context) {
    final isIos = defaultTargetPlatform == TargetPlatform.iOS;

    return Scaffold(
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 24),
          child: Column(
            children: [
              const Spacer(flex: 2),

              // Brand Logo
              ClipRRect(
                borderRadius: AppSpacing.borderRadiusXl,
                child: Image.asset(
                  'assets/images/logo_icon.png',
                  width: 80,
                  height: 80,
                ),
              ),
              const SizedBox(height: 12),

              // Brand Name — 遵循 lockup 设计: "GEN" 深色 + "EX" 渐变
              Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Text(
                    'GEN',
                    style: AppTypography.displayLarge.copyWith(
                      color: const Color(0xFF1A103A),
                      fontWeight: FontWeight.w800,
                      letterSpacing: -0.3,
                    ),
                  ),
                  ShaderMask(
                    shaderCallback: (bounds) => const LinearGradient(
                      colors: [Color(0xFF9B8FFF), Color(0xFFB8ADFF)],
                    ).createShader(bounds),
                    child: Text(
                      'EX',
                      style: AppTypography.displayLarge.copyWith(
                        color: Colors.white,
                        fontWeight: FontWeight.w800,
                        letterSpacing: -0.3,
                      ),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 6),

              // Slogan
              Text(
                context.t('welcome.slogan'),
                style: AppTypography.bodyLarge.copyWith(
                  color: AppColors.textSecondary,
                ),
              ),

              const Spacer(flex: 3),

              // Phone Register
              GenexButton(
                label: context.t('welcome.phoneRegister'),
                icon: Icons.phone_android_rounded,
                onPressed: () {
                  Navigator.pushNamed(context, '/register');
                },
              ),
              const SizedBox(height: 12),

              // Email Register
              GenexButton(
                label: context.t('welcome.emailRegister'),
                icon: Icons.email_outlined,
                variant: GenexButtonVariant.outline,
                onPressed: () {
                  Navigator.pushNamed(context, '/register', arguments: {'isEmail': true});
                },
              ),
              const SizedBox(height: 24),

              // Social Login Divider
              Row(
                children: [
                  const Expanded(child: Divider(color: AppColors.border)),
                  Padding(
                    padding: const EdgeInsets.symmetric(horizontal: 16),
                    child: Text(context.t('welcome.otherLogin'), style: AppTypography.caption),
                  ),
                  const Expanded(child: Divider(color: AppColors.border)),
                ],
              ),
              const SizedBox(height: 16),

              // Social Login Buttons
              // Android: 微信 + 支付宝 + Google
              // iOS:     微信 + 支付宝 + Google + Apple
              Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  _SocialLoginButton(
                    icon: Icons.wechat,
                    label: context.t('welcome.wechat'),
                    color: const Color(0xFF07C160),
                    loading: _wechatLoading,
                    onTap: _onWechatTap,
                  ),
                  const SizedBox(width: 20),
                  _SocialLoginButton(
                    // 支付宝官方蓝色
                    icon: Icons.account_balance_wallet_outlined,
                    label: context.t('welcome.alipay'),
                    color: const Color(0xFF1677FF),
                    loading: _alipayLoading,
                    onTap: _onAlipayTap,
                  ),
                  const SizedBox(width: 20),
                  _SocialLoginButton(
                    icon: Icons.g_mobiledata_rounded,
                    label: 'Google',
                    loading: _googleLoading,
                    onTap: _onGoogleTap,
                  ),
                  if (isIos) ...[
                    const SizedBox(width: 20),
                    _SocialLoginButton(
                      icon: Icons.apple_rounded,
                      label: 'Apple',
                      loading: _appleLoading,
                      onTap: _onAppleTap,
                    ),
                  ],
                ],
              ),
              const SizedBox(height: 32),

              // Already have account
              Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Text(context.t('welcome.hasAccount'), style: AppTypography.bodyMedium.copyWith(
                    color: AppColors.textSecondary,
                  )),
                  GestureDetector(
                    onTap: () {
                      Navigator.pushNamed(context, '/login');
                    },
                    child: Text(context.t('welcome.login'), style: AppTypography.labelMedium.copyWith(
                      color: AppColors.primary,
                    )),
                  ),
                ],
              ),
              const SizedBox(height: 16),

              // Terms
              Text(
                context.t('welcome.agreement'),
                style: AppTypography.caption.copyWith(fontSize: 10),
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 16),
            ],
          ),
        ),
      ),
    );
  }
}

class _SocialLoginButton extends StatelessWidget {
  final IconData icon;
  final String label;
  final Color? color;
  final VoidCallback onTap;
  final bool loading;

  const _SocialLoginButton({
    required this.icon,
    required this.label,
    required this.onTap,
    this.color,
    this.loading = false,
  });

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: loading ? null : onTap,
      child: Column(
        children: [
          Container(
            width: 52,
            height: 52,
            decoration: BoxDecoration(
              color: color != null ? color!.withValues(alpha: 0.1) : AppColors.gray50,
              shape: BoxShape.circle,
              border: Border.all(color: color?.withValues(alpha: 0.3) ?? AppColors.border),
            ),
            child: loading
                ? Padding(
                    padding: const EdgeInsets.all(14),
                    child: CircularProgressIndicator(
                      strokeWidth: 2,
                      color: color ?? AppColors.textPrimary,
                    ),
                  )
                : Icon(icon, size: 28, color: color ?? AppColors.textPrimary),
          ),
          const SizedBox(height: 6),
          Text(label, style: AppTypography.caption),
        ],
      ),
    );
  }
}