import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:miaoji_zhang/shared/services/session_store.dart';
import 'package:miaoji_zhang/shared/services/sync_service.dart';
import 'package:miaoji_zhang/shared/theme/app_theme.dart';
import 'package:miaoji_zhang/shared/widgets/app_controls.dart';
import 'package:miaoji_zhang/shared/widgets/app_icons.dart';

enum AiAccessState { guest, reauthenticate, aiDisabled, cloudDisabled }

AiAccessState? currentAiAccessState() {
  final session = SessionStore.instance;
  if (session.isGuest) return AiAccessState.guest;
  if (session.needsReauth) return AiAccessState.reauthenticate;
  if (!session.aiEnabled) return AiAccessState.aiDisabled;
  if (!session.cloudSyncEnabled) return AiAccessState.cloudDisabled;
  return null;
}

class AiAccessGate extends StatefulWidget {
  final AiAccessState state;
  final Future<void> Function()? onAction;

  const AiAccessGate({super.key, required this.state, this.onAction});

  @override
  State<AiAccessGate> createState() => _AiAccessGateState();
}

class _AiAccessGateState extends State<AiAccessGate> {
  bool _busy = false;

  String get _title => switch (widget.state) {
    AiAccessState.guest => '登录后使用 AI 助手',
    AiAccessState.reauthenticate => '登录状态已过期',
    AiAccessState.aiDisabled => 'AI 功能已关闭',
    AiAccessState.cloudDisabled => 'AI 功能需要云连接',
  };

  String get _message => switch (widget.state) {
    AiAccessState.guest => '游客账单会继续安全保存在本机。登录后即可使用 AI 聊天、语音解析和图片识别。',
    AiAccessState.reauthenticate => '本地记账不受影响。重新登录后可以继续使用 AI 和云同步。',
    AiAccessState.aiDisabled => '当前账号暂未开通 AI，手动记账和统计不受影响。',
    AiAccessState.cloudDisabled => '当前账号仅使用本地数据。开启云同步后才能发送 AI 消息。',
  };

  String? get _actionLabel => switch (widget.state) {
    AiAccessState.guest => '登录后使用',
    AiAccessState.reauthenticate => '重新登录',
    AiAccessState.aiDisabled => null,
    AiAccessState.cloudDisabled => '开启云同步',
  };

  Future<void> _act() async {
    if (_busy) return;
    if (widget.state == AiAccessState.aiDisabled) return;
    if (widget.onAction != null) {
      await widget.onAction!();
      return;
    }
    if (widget.state != AiAccessState.cloudDisabled) {
      if (mounted) {
        context.go(
          Uri(path: '/login', queryParameters: {'notice': _title}).toString(),
        );
      }
      return;
    }

    setState(() => _busy = true);
    try {
      await SessionStore.instance.setCloudSyncEnabled(true);
      await SyncService.instance.run();
    } finally {
      if (mounted) setState(() => _busy = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: SingleChildScrollView(
        padding: const EdgeInsets.all(28),
        child: ConstrainedBox(
          constraints: const BoxConstraints(maxWidth: 420),
          child: Card(
            child: Padding(
              padding: const EdgeInsets.fromLTRB(24, 28, 24, 24),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Container(
                    width: 62,
                    height: 62,
                    decoration: BoxDecoration(
                      color: context.jz.aiBackground,
                      borderRadius: BorderRadius.circular(20),
                    ),
                    child: Center(
                      child: AppIcons.icon(
                        AppIcons.sparkle,
                        size: 29,
                        color: AppTheme.ai,
                      ),
                    ),
                  ),
                  SizedBox(height: 18),
                  Text(
                    _title,
                    textAlign: TextAlign.center,
                    style: TextStyle(fontSize: 18, fontWeight: FontWeight.w800),
                  ),
                  SizedBox(height: 9),
                  Text(
                    _message,
                    textAlign: TextAlign.center,
                    style: TextStyle(
                      color: context.jz.text2,
                      fontSize: 12.5,
                      height: 1.6,
                    ),
                  ),
                  if (_actionLabel case final label?) ...[
                    SizedBox(height: 22),
                    SizedBox(
                      width: double.infinity,
                      child: JzActionButton(
                        label: label,
                        loading: _busy,
                        onPressed: _busy ? null : _act,
                      ),
                    ),
                  ],
                  if (widget.state == AiAccessState.guest) ...[
                    SizedBox(height: 12),
                    Text(
                      '无需登录也可以继续手动记账、管理预算和查看统计',
                      textAlign: TextAlign.center,
                      style: TextStyle(fontSize: 10.5, color: context.jz.text3),
                    ),
                  ],
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}