Prompt login dialog when user is unauthenticated during auth guard check.

frontend/src/app/guards/auth.guard.ts

@@ -1,7 +1,9 @@
 import {Injectable} from '@angular/core';
 import {ActivatedRouteSnapshot, CanActivate, Router, RouterStateSnapshot, UrlTree} from '@angular/router';
-import {Observable} from 'rxjs';
+import {map, Observable} from 'rxjs';
 import {AuthService} from '@services/auth.service';
+import {MatDialog} from '@angular/material/dialog';
+import {LoginDialogComponent} from '@shared-components/login/login.component';
 
 @Injectable({
   providedIn: 'root'
@@ -10,7 +12,8 @@ export class AuthGuard implements CanActivate {
 
   constructor(
     private authService: AuthService,
-    private router: Router
+    private router: Router,
+    private dialog: MatDialog
   ) {
   }
 
@@ -19,7 +22,16 @@ export class AuthGuard implements CanActivate {
     state: RouterStateSnapshot
   ): Observable<boolean | UrlTree> | Promise<boolean | UrlTree> | boolean | UrlTree {
     if (!this.authService.checkAuthStatus()) {
-      return this.router.createUrlTree(['/']);
+      this.router.createUrlTree(['/']);
+      const dialogRef = this.dialog.open(LoginDialogComponent);
+      return dialogRef.afterClosed().pipe(
+        map(result => {
+          if (result) {
+            return this.router.createUrlTree([state.url]);
+          }
+          return this.router.createUrlTree(['/']);
+        })
+      );
     }
 
     const requiredAuthorizations = route.data['requiredAuthorizations'] as string[];