functions/api/lib/model/response/point.dart

+import 'package:api/model/interface/point.dart';
+
+class PointResponse implements Point {
+  @override
+  final String id;
+
+  @override
+  final num latitude;
+
+  @override
+  final num longitude;
+
+  PointResponse({required this.id, required this.latitude, required this.longitude});
+}

functions/api/lib/model/response/route.dart

+import 'package:api/model/interface/route.dart';
+
+class RouteResponse implements Route {
+  @override
+  final Iterable<String> pointIds;
+
+  @override
+  final String userId;
+
+  @override
+  final String? teamId;
+
+  @override
+  final DateTime startTime;
+
+  @override
+  final DateTime endTime;
+
+  @override
+  final String id;
+
+  RouteResponse({required this.id, required this.pointIds, required this.userId, this.teamId, required this.startTime, required this.endTime});
+}

functions/api/lib/service/debt.dart

 import 'package:api/model/debt.dart';
+import 'package:api/model/interface/payment/user_to_user.dart';
+import 'package:api/model/interface/route.dart';
 import 'package:api/model/membership.dart';
-import 'package:api/model/payment/driven_distance_distributed.dart';
-import 'package:api/model/payment/equally_distributed.dart';
-import 'package:api/model/payment/user_to_user.dart';
-import 'package:api/service/distance_calculator.dart';
-import 'package:api/model/route.dart';
+import 'package:api/model/interface/payment/driven_distance_distributed.dart';
+import 'package:api/model/response/payment/equally_distributed.dart';
 
 class DebtService {
   final Stream<Membership> Function(String) getMembershipsByTeamId;
   final Future<Route> Function(String) getRouteById;
   final Stream<UserToUserPayment> Function(String) getUserToUserPayments;
-  final Stream<EquallyDistributedPayment> Function(String) getEquallyDistributedPayments;
+  final Stream<EquallyDistributedPaymentResponse> Function(String) getEquallyDistributedPayments;
   final Stream<DrivenDistanceDistributedPayment> Function(String) getDrivenDistanceDistributedPayments;
+  final Future<num> Function(Route) getDistance;
 
   DebtService({
     required this.getMembershipsByTeamId,
@@ -19,6 +19,7 @@ class DebtService {
     required this.getUserToUserPayments,
     required this.getEquallyDistributedPayments,
     required this.getDrivenDistanceDistributedPayments,
+    required this.getDistance,
   });
 
   Stream<Debt> getDebt(String userId) async* {
@@ -39,7 +40,7 @@ class DebtService {
     }
   }
 
-  Stream<Debt> calculateEquallyDistributedPaymentDebt(EquallyDistributedPayment payment) async* {
+  Stream<Debt> calculateEquallyDistributedPaymentDebt(EquallyDistributedPaymentResponse payment) async* {
     var teamMemberships = getMembershipsByTeamId(payment.teamId);
     var teamMemberIds = await teamMemberships.where((element) => element.joinedAt.compareTo(payment.createdAt) <= 0).map((e) => e.user.id).toList();
 
@@ -57,7 +58,7 @@ class DebtService {
     var distancePerUser = <String, num>{};
 
     await for (var route in paymentRoutes) {
-      distancePerUser[route.userId] = (distancePerUser[route.userId] ?? 0) + route.distance;
+      distancePerUser[route.userId] = (distancePerUser[route.userId] ?? 0) + await getDistance(route);
     }
 
     var fullDistance = distancePerUser.values.reduce((value, element) => value + element);

functions/api/lib/service/distance_calculator.dart

-import 'package:latlong2/latlong.dart' as latlong;
-import 'package:api/model/route.dart';
+import 'package:api/model/interface/point.dart';
+import 'package:api/model/interface/route.dart';
+import 'package:latlong2/latlong.dart';
 
-// TODO: as service
+class DistanceService {
+  final Future<Point> Function(String) getPointById;
 
-extension Distance on Route {
-  double get distance {
-    var distanceConverter = latlong.Distance();
+  DistanceService({required this.getPointById});
+
+  Future<num> calculateDistance(Route route) async {    
+    var points = Stream.fromFutures(route.pointIds.map((e) => getPointById(e)));
+    var distanceConverter = Distance();
     double distance = 0;
 
-    latlong.LatLng? lastPoint;
-    for (var point in points) {
-      var currentPoint = latlong.LatLng(point.latitude.toDouble(), point.longitude.toDouble());
+    LatLng? lastPoint;
+    await for (var point in points) {
+      var currentPoint = LatLng(point.latitude.toDouble(), point.longitude.toDouble());
       if (lastPoint != null) {
         distance += distanceConverter(lastPoint, currentPoint);
       }

functions/api/lib/service/membership_service.dart

@@ -6,7 +6,7 @@ import 'package:api/service/user_service.dart';
 import 'package:dart_appwrite/dart_appwrite.dart';
 import 'package:lib/lib.dart';
 
-class MembershipService extends ClientFunction {
+class MembershipService extends AppwriteClient {
   final UserService userService;
   final TeamService teamService;
 

functions/api/lib/service/team_service.dart

@@ -4,7 +4,7 @@ import 'package:api/model/team.dart';
 import 'package:dart_appwrite/dart_appwrite.dart';
 import 'package:lib/lib.dart';
 
-class TeamService extends ClientFunction {
+class TeamService extends AppwriteClient {
   late final Teams _teams;
 
   TeamService({required super.host, required super.projectId, required super.apiKey}) {

functions/api/lib/service/user_service.dart

@@ -2,7 +2,7 @@ import 'package:dart_appwrite/dart_appwrite.dart';
 import 'package:lib/lib.dart';
 import 'package:api/model/user.dart';
 
-class UserService extends ClientFunction {
+class UserService extends AppwriteClient {
   late final Users _users;
 
   UserService({required super.host, required super.projectId, required super.apiKey}) {

lib/lib/lib.dart

@@ -3,7 +3,7 @@
 /// More dartdocs go here.
 library;
 
-export 'src/interface/client_function.dart';
+export 'src/utils/appwrite_client.dart';
 export 'src/base_database.dart';
 export 'src/utils/variables.dart';
 export 'src/utils/request_handler.dart';
@@ -19,3 +19,4 @@ export 'src/db_api_endpoint.dart';
 export 'src/exceptions/db_action_forbidden.dart';
 export 'src/converter/list_response/list_to_response_converter.dart';
 export 'src/checked_db_api_endpoint.dart';
+export 'src/utils/api_helper.dart';

lib/lib/src/base_database.dart

@@ -3,13 +3,15 @@ import 'dart:async';
 import 'package:dart_appwrite/dart_appwrite.dart';
 import 'package:dart_appwrite/models.dart' as appwrite_models;
 import 'package:lib/src/exceptions/id_null.dart';
-import 'package:lib/src/interface/client_function.dart';
+import 'package:lib/src/utils/appwrite_client.dart';
 import 'package:lib/src/interface/db_model.dart';
 
-abstract class BaseDatabase<T extends DbModel, T1> extends ClientFunction {
+abstract class BaseDatabase<T extends DbModel, T1> extends AppwriteClient {
   static const String itemDataField = "data";
+
   final Map<String, dynamic> Function(T) itemToDbMap;
   final T1 Function(Map<String, dynamic>) itemFromDbMap;
+  
   late final Databases databases;
 
   String get databaseId;

lib/lib/src/db_api_endpoint.dart

@@ -5,7 +5,7 @@ import 'package:lib/src/base_database.dart';
 import 'package:lib/src/converter/list_response/list_to_response_converter.dart';
 import 'package:lib/src/interface/api_endpoint.dart';
 import 'package:lib/src/interface/db_model.dart';
-import 'package:lib/src/utils/map_helper.dart';
+import 'package:lib/src/utils/api_helper.dart';
 import 'package:lib/src/utils/variables.dart';
 
 class DbApiEndpoint<T extends DbModel, T1> extends ApiEndpoint {
@@ -24,12 +24,12 @@ class DbApiEndpoint<T extends DbModel, T1> extends ApiEndpoint {
 
   @override
   Future<Map<String, dynamic>> handleGet(context) async {
-    if(hasBodyKey(context, RequestResponseVariables.idFieldName)) {
+    if(ApiHelper.hasBodyField(context, RequestResponseVariables.idFieldName)) {
       var id = idFromContext(context);
       var item = await getFromId(id);
       return context.res.json(itemToResponse(item));
     }
-    else if(hasBodyKey(context, RequestResponseVariables.queriesFieldName)) {
+    else if(ApiHelper.hasBodyField(context, RequestResponseVariables.queriesFieldName)) {
       var queryRequest = queryRequestFromContext(context);
       var items = await getFromQueries(queryRequest).toList();
       return listResponse(context, items, itemToResponse);
@@ -83,21 +83,10 @@ class DbApiEndpoint<T extends DbModel, T1> extends ApiEndpoint {
   }
 
   String idFromContext(final context) {
-    var map = jsonDecode(context.req.body);
-    return getRequiredMapItem<String>(RequestResponseVariables.idFieldName, map);
+    return ApiHelper.fieldFromRequestBody(context, RequestResponseVariables.idFieldName);
   }
 
   Iterable<String> queryRequestFromContext(final context) {
-    var map = jsonDecode(context.req.body);
-    return getRequiredMapItem<Iterable<String>>(RequestResponseVariables.queriesFieldName, map);
-  }
-
-  bool hasBodyKey(final context, String key) {
-    try {
-      var map = jsonDecode(context.req.body) as Map<String, dynamic>;
-      return map.containsKey(key);
-    } on FormatException catch(_) {
-      return false;
-    }
+    return ApiHelper.fieldFromRequestBody(context, RequestResponseVariables.queriesFieldName);
   }
 }

lib/lib/src/utils/api_helper.dart

+import 'dart:convert';
+
+import 'package:lib/src/utils/map_helper.dart';
+
+abstract class ApiHelper  {
+  static T fieldFromRequestBody<T>(final context, String fieldName) {
+    var map = jsonDecode(context.req.body);
+    return getRequiredMapItem<T>(fieldName, map);
+  }
+
+  static bool hasBodyField(final context, String key) {
+    try {
+      var map = jsonDecode(context.req.body) as Map<String, dynamic>;
+      return map.containsKey(key);
+    } on FormatException catch(_) {
+      return false;
+    }
+  }
+}

lib/lib/src/interface/client_function.dart → lib/lib/src/utils/appwrite_client.dart

 import 'package:dart_appwrite/dart_appwrite.dart';
 
-abstract class ClientFunction {
+class AppwriteClient {
   final Client client;
 
-  ClientFunction({required String host, required String projectId, required String apiKey}) :
+  AppwriteClient({required String host, required String projectId, required String apiKey}) :
     client = Client(endPoint: host)
       .setProject(projectId)
       .setKey(apiKey)