CacheManager FileService with custom validity

file_service_with_custom_validity.dart

import 'package:flutter_cache_manager/flutter_cache_manager.dart';
import 'package:http/http.dart' as http;
import 'package:clock/clock.dart';

const cacheKey = 'cache';
final cacheManager = CacheManager(Config(
  cacheKey,
  fileService: CustomFileService(),
));
const validity = Duration(days: 7);

class CustomFileService extends FileService {
  http.Client _httpClient;
  CustomFileService({http.Client httpClient}) {
    _httpClient = httpClient ?? http.Client();
  }

  @override
  Future<FileServiceResponse> get(String url,
      {Map<String, String> headers = const {}}) async {
    final req = http.Request('GET', Uri.parse(url));
    req.headers.addAll(headers);
    final httpResponse = await _httpClient.send(req);

    return HttpResponseWithValidity(httpResponse);
  }
}

class HttpResponseWithValidity extends HttpGetResponse {
  final DateTime _receivedTime = clock.now();
  HttpResponseWithValidity(http.StreamedResponse response) : super(response);
  @override
  DateTime get validTill => _receivedTime.add(validity);
}