import 'package:dartz/dartz.dart';
import '../../../../core/errors/failures.dart';
import '../entities/scan_entity.dart';
import '../repositories/scanner_repository.dart';

/// Use case for saving scan data
/// Handles the business logic for saving scan information to both remote and local storage
class SaveScanUseCase {
  final ScannerRepository repository;

  SaveScanUseCase(this.repository);

  /// Execute the save scan operation
  ///
  /// First saves to remote server, then saves locally only if remote save succeeds
  /// This ensures data consistency and allows for offline-first behavior
  Future<Either<Failure, void>> call(SaveScanParams params) async {
    // Validate input parameters
    final validationResult = _validateParams(params);
    if (validationResult != null) {
      return Left(ValidationFailure(validationResult));
    }

    try {
      // Save to remote server first
      final remoteResult = await repository.saveScan(
        barcode: params.barcode,
        field1: params.field1,
        field2: params.field2,
        field3: params.field3,
        field4: params.field4,
      );

      return remoteResult.fold(
        (failure) => Left(failure),
        (_) async {
          // If remote save succeeds, save to local storage
          final scanEntity = ScanEntity(
            barcode: params.barcode,
            timestamp: DateTime.now(),
            field1: params.field1,
            field2: params.field2,
            field3: params.field3,
            field4: params.field4,
          );

          final localResult = await repository.saveScanLocally(scanEntity);
          return localResult.fold(
            (failure) {
              // Log the local save failure but don't fail the entire operation
              // since remote save succeeded
              return const Right(null);
            },
            (_) => const Right(null),
          );
        },
      );
    } catch (e) {
      return Left(UnknownFailure('Failed to save scan: ${e.toString()}'));
    }
  }

  /// Validate the input parameters
  String? _validateParams(SaveScanParams params) {
    if (params.barcode.trim().isEmpty) {
      return 'Barcode cannot be empty';
    }

    if (params.field1.trim().isEmpty) {
      return 'Field 1 cannot be empty';
    }

    if (params.field2.trim().isEmpty) {
      return 'Field 2 cannot be empty';
    }

    if (params.field3.trim().isEmpty) {
      return 'Field 3 cannot be empty';
    }

    if (params.field4.trim().isEmpty) {
      return 'Field 4 cannot be empty';
    }

    return null;
  }
}

/// Parameters for the SaveScanUseCase
class SaveScanParams {
  final String barcode;
  final String field1;
  final String field2;
  final String field3;
  final String field4;

  SaveScanParams({
    required this.barcode,
    required this.field1,
    required this.field2,
    required this.field3,
    required this.field4,
  });

  @override
  String toString() {
    return 'SaveScanParams{barcode: $barcode, field1: $field1, field2: $field2, field3: $field3, field4: $field4}';
  }
}