feat: add user creation on login (wip)

frontend/src/app/service/user.service.ts

@@ -0,0 +1,34 @@
+import { inject, Injectable } from '@angular/core';
+import { HttpClient } from '@angular/common/http';
+import { KeycloakProfile } from 'keycloak-js';
+import { async } from 'rxjs';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class UserService {
+  private http: HttpClient = inject(HttpClient);
+
+  public getUser(id: string) {
+    return this.http.get<{ keycloakId: string, username: string } | null>(`/backend/user/${id}`);
+  }
+
+  public createUser(id: string, username: string) {
+    return this.http.post<{ keycloakId: string, username: string }>('/backend/user', {
+      keycloakId: id,
+      username: username,
+    });
+  }
+
+  public async getCurrentUser(userProfile: KeycloakProfile) {
+    if (userProfile.id == null) {
+      return;
+    }
+    return await this.getUser(userProfile.id).toPromise().then(async user => {
+      if (user) {
+        return user;
+      }
+      return await this.createUser(userProfile.id ?? '', userProfile.username ?? '').toPromise();
+    });
+  }
+}