import 'dart:async';
import 'dart:convert';

import 'package:flutter/foundation.dart';
import 'package:http/http.dart' as http;
import 'package:package_info_plus/package_info_plus.dart';
import 'package:sentry_flutter/sentry_flutter.dart';

import '../models/closed_tab.dart';
import '../models/closed_tab_item.dart';
import '../utils/app_config.dart';
import 'bar_tab_service.dart';

abstract class ExportService {
  Future<void> uploadToServer();
}

/// Uploads the closed-tab history to the backup server. Best effort: a
/// failed backup is logged but never interrupts the bar.
class DefaultExportService implements ExportService {
  final BarTabService barTabService;
  final Future<String?> Function()? authToken;
  final http.Client _client;

  DefaultExportService({
    required this.barTabService,
    this.authToken,
    http.Client? client,
  }) : _client = client ?? http.Client();

  static const _timeout = Duration(seconds: 30);

  @override
  Future<void> uploadToServer() async {
    try {
      final closedTabs = await barTabService.getClosedTabs();
      final appVersion = (await PackageInfo.fromPlatform()).version;
      final token = await authToken?.call();

      final response = await _client
          .post(
            Uri.parse(kExportServerUrl),
            headers: {
              'Content-Type': 'application/json',
              if (token != null) 'Authorization': 'Bearer $token',
            },
            body: jsonEncode(_buildPayload(closedTabs, appVersion: appVersion)),
          )
          .timeout(_timeout);

      if (response.statusCode != 200 && response.statusCode != 201) {
        unawaited(
          Sentry.captureMessage(
            'Backup upload failed with HTTP ${response.statusCode}',
            level: SentryLevel.warning,
          ),
        );
      }
    } on Exception catch (e) {
      // Mostly offline tablets; not worth an error report.
      debugPrint('ExportService: backup upload failed: $e');
    }
  }

  Map<String, dynamic> _buildPayload(
    List<ClosedTab> tabs, {
    required String appVersion,
  }) {
    return {
      'exportedAt': DateTime.now().toIso8601String(),
      'appVersion': appVersion,
      'closedTabs': tabs.map(_tabToJson).toList(),
    };
  }

  Map<String, dynamic> _tabToJson(ClosedTab tab) {
    return {
      'id': tab.id,
      'originalTabId': tab.originalTabId,
      'customerName': tab.customerName,
      'closedAt': tab.closedAt.toIso8601String(),
      'paymentMethod': tab.paymentMethod.value,
      'items': tab.items.map(_itemToJson).toList(),
      'itemCount': tab.itemCount,
      'totalInCents': tab.totalInCents,
    };
  }

  Map<String, dynamic> _itemToJson(ClosedTabItem item) {
    return {
      'productId': item.productId,
      'productName': item.productName,
      'quantity': item.quantity,
      'unitPriceInCents': item.unitPriceInCents,
      'purchasedAt': item.purchasedAt?.toIso8601String(),
      'removedAt': item.removedAt?.toIso8601String(),
      'isRemoved': item.isRemoved,
      'lineTotalInCents': item.lineTotalInCents,
    };
  }
}