import 'package:flutter/material.dart';

import '../../theme/app_theme.dart';
import '../services/market_history_admin_api.dart';

enum AdminGateStatus { loading, authorized, forbidden, unauthorized, error }

/// Probes admin API access before showing [child].
///
/// Calls `GET /v1/admin/market-history/sync-runs?limit=1`.
/// Returns 403 → not authorized UI; 200 → [child].
class AdminGate extends StatefulWidget {
  const AdminGate({
    super.key,
    required this.child,
    this.api,
  });

  final Widget child;
  final MarketHistoryAdminApi? api;

  @override
  State<AdminGate> createState() => _AdminGateState();
}

class _AdminGateState extends State<AdminGate> {
  AdminGateStatus _status = AdminGateStatus.loading;
  String? _errorMessage;

  @override
  void initState() {
    super.initState();
    _probe();
  }

  Future<void> _probe() async {
    final MarketHistoryAdminApi api = widget.api ?? MarketHistoryAdminApi();
    try {
      await api.fetchSyncRuns(limit: 1);
      if (!mounted) {
        return;
      }
      setState(() => _status = AdminGateStatus.authorized);
    } on MarketHistoryAdminApiException catch (e) {
      if (!mounted) {
        return;
      }
      setState(() {
        _errorMessage = e.message;
        _status = switch (e.statusCode) {
          401 => AdminGateStatus.unauthorized,
          403 => AdminGateStatus.forbidden,
          _ => AdminGateStatus.error,
        };
      });
    } catch (e) {
      if (!mounted) {
        return;
      }
      setState(() {
        _status = AdminGateStatus.error;
        _errorMessage = e.toString();
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return switch (_status) {
      AdminGateStatus.loading => const Scaffold(
          key: Key('admin-gate-loading'),
          body: Center(
            child: CircularProgressIndicator(color: AppColors.accent),
          ),
        ),
      AdminGateStatus.authorized => widget.child,
      AdminGateStatus.forbidden => _messageScaffold(
          key: const Key('admin-gate-forbidden'),
          title: 'Not authorized',
          message: 'Your account does not have admin access.',
          icon: Icons.lock_outline,
        ),
      AdminGateStatus.unauthorized => _messageScaffold(
          key: const Key('admin-gate-unauthorized'),
          title: 'Sign in required',
          message: 'Sign in again to access the admin portal.',
          icon: Icons.login,
        ),
      AdminGateStatus.error => _messageScaffold(
          key: const Key('admin-gate-error'),
          title: 'Admin check failed',
          message: _errorMessage ?? 'Unknown error',
          icon: Icons.error_outline,
          showRetry: true,
        ),
    };
  }

  Widget _messageScaffold({
    required Key key,
    required String title,
    required String message,
    required IconData icon,
    bool showRetry = false,
  }) {
    return Scaffold(
      key: key,
      appBar: AppBar(title: const Text('Admin portal')),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              Icon(icon, size: 40, color: AppColors.textSecondary),
              const SizedBox(height: 12),
              Text(
                title,
                style: Theme.of(context).textTheme.titleLarge,
                textAlign: TextAlign.center,
              ),
              const SizedBox(height: 8),
              Text(
                message,
                style: const TextStyle(color: AppColors.textSecondary),
                textAlign: TextAlign.center,
              ),
              if (showRetry) ...<Widget>[
                const SizedBox(height: 16),
                FilledButton(
                  onPressed: () {
                    setState(() => _status = AdminGateStatus.loading);
                    _probe();
                  },
                  child: const Text('Retry'),
                ),
              ],
            ],
          ),
        ),
      ),
    );
  }
}