add membership api endpoint

functions/api/lib/api_endpoint/membership.dart

+import 'package:api/converter/request_response/membership.dart';
+import 'package:api/model/membership.dart';
+import 'package:api/model/user.dart';
+import 'package:lib/lib.dart';
+
+class MembershipApiEndpoint extends ApiEndpoint {
+  static const String teamIdFieldName = "teamId";
+  static const String userIdFieldName = "userId";
+
+  final User requestingUser;
+  final Stream<Membership> Function(String) getMembershipsByUserId;
+  final Stream<Membership> Function(String) getMembershipsByTeamId;
+  final Map<String, dynamic> Function(Membership) itemToResponse = MembershipRequestResponseConverter.toResponseData;
+
+  MembershipApiEndpoint({
+    required this.requestingUser,
+    required this.getMembershipsByUserId,
+    required this.getMembershipsByTeamId,
+  });
+
+  @override
+  Future<Map<String, dynamic>> handleDelete(context) {
+    throw ApiActionForbiddenException("delete", "membership");
+  }
+
+  @override
+  Future<Map<String, dynamic>> handleGet(context) async {
+    Stream<Membership> memberships;
+    if(ApiHelper.hasBodyField(context, teamIdFieldName)) {
+      var requestingUserTeamIds = await getMembershipsByUserId(requestingUser.id).map((e) => e.team.id).toList();
+      var teamId = ApiHelper.fieldFromRequestBody<String>(context, teamIdFieldName);
+      memberships = getMembershipsByTeamId(teamId).where((e) => requestingUserTeamIds.contains(e.team.id));
+    }
+    else {
+      var userId = ApiHelper.fieldFromRequestBody<String>(context, userIdFieldName);
+      if(userId != requestingUser.id) {
+        throw UnauthorizedException();
+      }
+
+      memberships = getMembershipsByUserId(userId);
+    }
+
+    return listResponse(context, await memberships.toList(), itemToResponse);
+  }
+
+  @override
+  Future<Map<String, dynamic>> handlePost(context) {
+    throw ApiActionForbiddenException("post", "membership");
+  }
+
+  @override
+  Future<Map<String, dynamic>> handlePut(context) {
+    throw ApiActionForbiddenException("put", "membership");
+  }
+}

functions/api/lib/converter/request_response/membership.dart

+import 'package:api/model/membership.dart';
+
+class MembershipRequestResponseConverter {
+  static const String userIdRequestResponseFieldName = "userId";
+  static const String teamIdRequestResponseFieldName = "teamId";
+
+  static Map<String, dynamic> toResponseData(Membership response) {
+    return {
+      userIdRequestResponseFieldName: response.user.id,
+      teamIdRequestResponseFieldName: response.team.id,
+    };
+  }
+}

functions/api/lib/main.dart

 import 'dart:async';
 import 'dart:io';
 import 'package:api/api_endpoint/calendar_event.dart';
+import 'package:api/api_endpoint/membership.dart';
 import 'package:api/api_endpoint/payment/driven_distance_distributed.dart';
 import 'package:api/api_endpoint/payment/equally_distributed.dart';
 import 'package:api/api_endpoint/payment/user_to_user.dart';
@@ -38,6 +39,7 @@ const String drivenDistanceDistributedPaymentApiEndpoint = "/payment/team/driven
 const String equallyDistributedPaymentApiEndpoint = "/payment/team/equal";
 const String userToUserPaymentApiEndpoint = "/payment/user";
 const String debtApiEndpoint = "/debt";
+const String membershipApiEndpoint = "/membership";
 
 Future<dynamic> main(final context) async {
   final host = "https://${context.req.host}/v1";
@@ -184,6 +186,14 @@ Future<dynamic> main(final context) async {
       );
       break;
 
+    case membershipApiEndpoint:
+      var requestingUser = await getRequestingUser(context, userService);
+      apiEndpoint = MembershipApiEndpoint(
+        requestingUser: requestingUser,
+        getMembershipsByTeamId: membershipService.getTeamMemberships,
+        getMembershipsByUserId: membershipService.getUserMemberships,
+      );
+
     default:
       throw HttpException("Path $requestPath not found", uri: Uri.parse(context.req.url));
   }