import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:new_learn/core/providers/privacy_provider.dart';
import 'package:new_learn/core/storage/privacy_storage.dart';
import 'package:new_learn/features/auth/legal_documents.dart';

/// ============================================================
/// 【PrivacyConsentPage】首次启动隐私协议页
///
/// 作用：
///   1. 用户首次打开 App 时，先展示隐私说明；
///   2. 用户点击"同意并继续"后，保存本地状态并放行进入主流程；
///   3. 用户点击"暂不同意"时，维持拦截状态（Android 可直接退出应用）。
///
/// 这里是"应用启动级"协议页，不等同于登录页里的协议勾选：
///   - 启动协议：未登录前就要先拦；
///   - 登录页协议：属于业务表单校验，发生在点击登录时。
/// ============================================================
class PrivacyConsentPage extends StatefulWidget {
  const PrivacyConsentPage({super.key});

  @override
  State<PrivacyConsentPage> createState() => _PrivacyConsentPageState();
}

class _PrivacyConsentPageState extends State<PrivacyConsentPage> {
  bool _submitting = false;
  _LegalDocumentData? _activeDocument;

  Future<void> _openLegalDocument({
    required String title,
    required String content,
  }) async {
    if (!mounted) return;
    setState(() {
      _activeDocument = _LegalDocumentData(
        title: title,
        content: content,
      );
    });
  }

  Future<void> _accept() async {
    if (_submitting) return;
    setState(() => _submitting = true);
    await PrivacyStorage.instance.saveAccepted(true);
    // 更新全局门禁状态：启动 Gate 和 go_router 守卫都会同步放行。
    privacyAcceptedNotifier.value = true;
    if (mounted) {
      setState(() => _submitting = false);
    }
  }

  Future<void> _decline() async {
    final result = await showDialog<bool>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: const Text('提示'),
        content: const Text('若您不同意隐私政策，将无法使用我们的服务'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(dialogContext).pop(true),
            child: const Text('重新考虑'),
          ),
          FilledButton(
            onPressed: () => Navigator.of(dialogContext).pop(false),
            child: const Text('退出'),
          ),
        ],
      ),
    );

    // 选"重新考虑"或直接关闭弹窗，都继续停留在当前隐私页。
    if (result != false) return;

    await PrivacyStorage.instance.saveAccepted(false);
    privacyAcceptedNotifier.value = false;
    // Android 上按常见做法直接退出应用；其他平台调用也安全，无法退出时只是不生效。
    await SystemNavigator.pop();
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final activeDocument = _activeDocument;

    if (activeDocument != null) {
      return PopScope(
        canPop: false,
        onPopInvokedWithResult: (didPop, result) {
          if (didPop) return;
          setState(() => _activeDocument = null);
        },
        child: Scaffold(
          backgroundColor: const Color(0xFFF5F7FA),
          appBar: AppBar(
            title: Text(activeDocument.title),
            leading: IconButton(
              onPressed: () => setState(() => _activeDocument = null),
              icon: const Icon(Icons.arrow_back),
            ),
          ),
          body: SafeArea(
            child: SingleChildScrollView(
              padding: const EdgeInsets.fromLTRB(16, 16, 16, 24),
              child: Container(
                width: double.infinity,
                padding: const EdgeInsets.all(16),
                decoration: BoxDecoration(
                  color: Colors.white,
                  borderRadius: BorderRadius.circular(16),
                ),
                child: SelectableText(
                  activeDocument.content,
                  style: const TextStyle(
                    fontSize: 14,
                    height: 1.8,
                    color: Color(0xFF323233),
                  ),
                ),
              ),
            ),
          ),
        ),
      );
    }

    return Scaffold(
      backgroundColor: Colors.white,
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(24, 24, 24, 20),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                '欢迎使用爱学蝶变',
                style: theme.textTheme.headlineSmall?.copyWith(
                  fontWeight: FontWeight.w700,
                ),
              ),
              const SizedBox(height: 16),
              Text(
                '为保障你的个人信息安全，在继续使用前，请先阅读并同意《用户协议》和《隐私政策》。同意后我们才会继续进入 App 的登录和业务流程。',
                style: theme.textTheme.bodyLarge?.copyWith(
                  color: const Color(0xFF4B5563),
                  height: 1.7,
                ),
              ),
              const SizedBox(height: 20),
              Expanded(
                child: Container(
                  width: double.infinity,
                  padding: const EdgeInsets.all(16),
                  decoration: BoxDecoration(
                    color: const Color(0xFFF8FAFC),
                    borderRadius: BorderRadius.circular(16),
                  ),
                  child: SingleChildScrollView(
                    child: Text(
                      '1. 我们会在必要范围内使用账号信息、设备信息，用于登录鉴权、学习记录同步、功能服务提供。\n\n'
                      '2. 未经你的明确同意，我们不会将你的个人信息用于与学习无关的用途。\n\n'
                      '3. 你可以通过《用户协议》和《隐私政策》了解信息收集、使用、存储与保护方式。\n\n'
                      '4. 若你不同意本协议内容，将无法继续进入 App 主流程。',
                      style: theme.textTheme.bodyMedium?.copyWith(
                        color: const Color(0xFF475569),
                        height: 1.8,
                      ),
                    ),
                  ),
                ),
              ),
              const SizedBox(height: 16),
              Wrap(
                spacing: 4,
                runSpacing: 4,
                children: [
                  Text(
                    '点击“同意并继续”即表示你已阅读并同意',
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: const Color(0xFF64748B),
                    ),
                  ),
                  InkWell(
                    onTap: () => _openLegalDocument(
                        title: kUserAgreementTitle,
                        content: kUserAgreementContent,
                      ),
                    child: const Text(
                      '《用户协议》',
                      style: TextStyle(
                        color: Color(0xFF2563EB),
                        fontSize: 12,
                      ),
                    ),
                  ),
                  Text(
                    '和',
                    style: theme.textTheme.bodySmall?.copyWith(
                      color: const Color(0xFF64748B),
                    ),
                  ),
                  InkWell(
                    onTap: () => _openLegalDocument(
                        title: kPrivacyPolicyTitle,
                        content: kPrivacyPolicyContent,
                      ),
                    child: const Text(
                      '《隐私政策》',
                      style: TextStyle(
                        color: Color(0xFF2563EB),
                        fontSize: 12,
                      ),
                    ),
                  ),
                ],
              ),
              const SizedBox(height: 20),
              Row(
                children: [
                  Expanded(
                    child: OutlinedButton(
                      onPressed: _submitting ? null : _decline,
                      style: OutlinedButton.styleFrom(
                        minimumSize: const Size.fromHeight(48),
                      ),
                      child: const Text('暂不同意'),
                    ),
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    child: FilledButton(
                      onPressed: _submitting ? null : _accept,
                      style: FilledButton.styleFrom(
                        minimumSize: const Size.fromHeight(48),
                      ),
                      child: _submitting
                          ? const SizedBox(
                              width: 18,
                              height: 18,
                              child: CircularProgressIndicator(
                                strokeWidth: 2,
                                color: Colors.white,
                              ),
                            )
                          : const Text('同意并继续'),
                    ),
                  ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class _LegalDocumentData {
  const _LegalDocumentData({
    required this.title,
    required this.content,
  });

  final String title;
  final String content;
}