Add DataStoreService

Added service handling local data. Use this service so we can change the used technology (cookie, local storage, ..) easily.

src/app/app.module.ts

@@ -64,6 +64,7 @@ import { CreatorHomeScreenComponent } from './creator-home-screen/creator-home-s
 import { CreateCommentComponent } from './create-comment/create-comment.component';
 import { CommentService } from './comment.service';
 import { ParticipantHomeScreenComponent } from './participant-home-screen/participant-home-screen.component';
+import { DataStoreService } from './data-store.service';
 
 @NgModule({
   declarations: [
@@ -138,6 +139,7 @@ import { ParticipantHomeScreenComponent } from './participant-home-screen/partic
     NotificationService,
     AuthenticationService,
     AuthenticationGuard,
+    DataStoreService,
     RoomService,
     CommentService
   ],

src/app/data-store.service.spec.ts

+import { TestBed, inject } from '@angular/core/testing';
+
+import { DataStoreService } from './data-store.service';
+
+describe('DataStoreService', () => {
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      providers: [DataStoreService]
+    });
+  });
+
+  it('should be created', inject([DataStoreService], (service: DataStoreService) => {
+    expect(service).toBeTruthy();
+  }));
+});

src/app/data-store.service.ts

+import { Injectable } from '@angular/core';
+
+/**
+ * Service for storing local user data.
+ * Use this service to allow switching between localStorage, cookies, .. easily.
+ */
+@Injectable()
+export class DataStoreService {
+  has(key: string): boolean {
+    return key in localStorage;
+  }
+
+  get(key: string): string {
+    return localStorage.getItem(key);
+  }
+
+  set(key: string, data: string) {
+    localStorage.setItem(key, data);
+  }
+
+  remove(key: string) {
+    localStorage.removeItem(key);
+  }
+}