import 'package:pad_scanner/services/api_service.dart';
import 'package:pad_scanner/services/app_config_service.dart';

enum BoxingActionErrorKind { missingApiUrl, network, duplicate, backend }

class BoxingActionResult<T> {
  final bool success;
  final T? data;
  final BoxingActionErrorKind? errorKind;
  final String? errorMessage;
  final int? boxNo;

  const BoxingActionResult._({
    required this.success,
    this.data,
    this.errorKind,
    this.errorMessage,
    this.boxNo,
  });

  const BoxingActionResult.ok(T data) : this._(success: true, data: data);

  const BoxingActionResult.error({
    required BoxingActionErrorKind kind,
    required String message,
    int? boxNo,
  }) : this._(
         success: false,
         errorKind: kind,
         errorMessage: message,
         boxNo: boxNo,
       );
}

typedef ApiUrlLoader = Future<String?> Function();

class BoxingApiActions {
  static const networkErrorMessage = '网络异常，请检查网络连接';
  static const missingApiUrlMessage = '未配置 API 地址，请前往设置';

  final ApiService _apiService;
  final ApiUrlLoader _loadApiUrl;

  BoxingApiActions({required ApiService apiService, ApiUrlLoader? loadApiUrl})
    : _apiService = apiService,
      _loadApiUrl =
          loadApiUrl ?? (() => AppConfigService().getString('api_url'));

  Future<BoxingActionResult<BoxInfoResult>> fetchBoxInfo(String zongpai) async {
    final baseUrl = await _requireBaseUrl();
    if (baseUrl == null) return _missingApiUrl();

    final result = await _apiService.fetchBoxInfo(
      baseUrl: baseUrl,
      zongpaiNo: zongpai,
    );
    if (result.success) return BoxingActionResult.ok(result);
    return BoxingActionResult.error(
      kind: _kindForMessage(result.errorMessage),
      message: result.errorMessage ?? '查询失败',
    );
  }

  Future<BoxingActionResult<BoxSaveResult>> saveBoxRecord({
    required String zongpaiNo,
    required int boxNo,
    required int quantity,
  }) async {
    final baseUrl = await _requireBaseUrl();
    if (baseUrl == null) return _missingApiUrl();

    final result = await _apiService.saveBoxRecord(
      baseUrl: baseUrl,
      zongpaiNo: zongpaiNo,
      boxNo: boxNo,
      quantity: quantity,
    );
    return _saveResult(result, fallbackMessage: '提交失败');
  }

  Future<BoxingActionResult<BoxSaveResult>> updateBoxRecord({
    required int boxItemId,
    required int boxNo,
    required int quantity,
  }) async {
    final baseUrl = await _requireBaseUrl();
    if (baseUrl == null) return _missingApiUrl();

    final result = await _apiService.updateBoxRecord(
      baseUrl: baseUrl,
      boxItemId: boxItemId,
      boxNo: boxNo,
      quantity: quantity,
    );
    return _saveResult(result, fallbackMessage: '修改失败');
  }

  Future<BoxingActionResult<BoxDeleteResult>> deleteBoxRecord({
    required int boxItemId,
  }) async {
    final baseUrl = await _requireBaseUrl();
    if (baseUrl == null) return _missingApiUrl();

    final result = await _apiService.deleteBoxRecord(
      baseUrl: baseUrl,
      boxItemId: boxItemId,
    );
    if (result.success) return BoxingActionResult.ok(result);
    return BoxingActionResult.error(
      kind: _kindForMessage(result.errorMessage),
      message: result.errorMessage ?? '删除失败',
    );
  }

  Future<String?> _requireBaseUrl() async {
    final baseUrl = await _loadApiUrl() ?? '';
    if (baseUrl.isEmpty) return null;
    return baseUrl;
  }

  BoxingActionResult<T> _missingApiUrl<T>() {
    return const BoxingActionResult.error(
      kind: BoxingActionErrorKind.missingApiUrl,
      message: missingApiUrlMessage,
    );
  }

  BoxingActionResult<BoxSaveResult> _saveResult(
    BoxSaveResult result, {
    required String fallbackMessage,
  }) {
    if (result.success) return BoxingActionResult.ok(result);
    if (result.isDuplicate) {
      return BoxingActionResult.error(
        kind: BoxingActionErrorKind.duplicate,
        message: result.errorMessage ?? fallbackMessage,
        boxNo: result.boxNo,
      );
    }
    return BoxingActionResult.error(
      kind: _kindForMessage(result.errorMessage),
      message: result.errorMessage ?? fallbackMessage,
    );
  }

  BoxingActionErrorKind _kindForMessage(String? message) {
    if (message == networkErrorMessage) return BoxingActionErrorKind.network;
    return BoxingActionErrorKind.backend;
  }
}