implement authentication and reusable data table

src/app/core/services/permission.service.ts

@@ -0,0 +1,34 @@
+import { HttpClient } from '@angular/common/http';
+import { Injectable, inject, signal } from '@angular/core';
+import { map, Observable, tap } from 'rxjs';
+import { API_CONFIG } from '../config/api.config';
+import { PermissionContext } from '../models/context.model';
+
+interface PermissionResponse {
+  roles?: string[];
+  permissions?: string[];
+  defaultLandingPage?: string;
+}
+
+@Injectable({ providedIn: 'root' })
+export class PermissionService {
+  private readonly http = inject(HttpClient);
+  readonly permissionContext = signal<PermissionContext | null>(null);
+
+  loadPermissions(): Observable<PermissionContext> {
+    return this.http.get<PermissionResponse>(`${API_CONFIG.baseUrl}${API_CONFIG.endpoints.permissionContext}`).pipe(
+      map((response) => ({
+        roles: response.roles ?? [],
+        permissions: response.permissions ?? [],
+        defaultLandingPage: response.defaultLandingPage?.trim() || undefined,
+      })),
+      tap((context) => {
+        this.permissionContext.set(context);
+      })
+    );
+  }
+
+  clear(): void {
+    this.permissionContext.set(null);
+  }
+}