Fix authentication errors handling.

frontend/src/app/core/guard/authentication.guard.ts

@@ -0,0 +1,18 @@
+import { inject } from "@angular/core";
+import { CanActivateFn, Router } from "@angular/router";
+import { AuthenticationService } from "../service/authentication.service";
+import { MatSnackBar } from "@angular/material/snack-bar";
+
+export const authenticationGuard: CanActivateFn = () => {
+    const authenticationService = inject(AuthenticationService);
+    const router = inject(Router);
+    const snackBar = inject(MatSnackBar);
+
+    if (authenticationService.isAuthenticated()) {
+        return true;
+    } else {
+        router.navigate(['/login']);
+        snackBar.open('You are unauthenticated. Please, log-in first.', 'Close', { duration: 5000 });
+        return false;
+    }
+}

frontend/src/app/core/interceptor/jwt.interceptor.ts

@@ -1,29 +1,88 @@
-import { Observable } from 'rxjs';
+import { HttpErrorResponse, HttpEvent, HttpHandler, HttpInterceptor, HttpRequest } from '@angular/common/http';
 import { inject, Injectable } from '@angular/core';
-import { HttpInterceptor, HttpRequest, HttpHandler, HttpEvent } from '@angular/common/http';
+import { catchError, filter, Observable, Subject, switchMap, take, throwError } from 'rxjs';
+import { RefreshTokenRequest } from '../rest-services/user/model/refresh-token.model';
+import { UserRestService } from '../rest-services/user/user.rest-service';
 import { AuthenticationService } from '../service/authentication.service';
+import { Router } from '@angular/router';
+import { MatSnackBar } from '@angular/material/snack-bar';
 
 @Injectable()
 export class JwtInterceptor implements HttpInterceptor {
     private readonly authenticationService = inject(AuthenticationService);
+    private readonly router = inject(Router);
+    private readonly userRestService = inject(UserRestService);
+    private readonly snackBar = inject(MatSnackBar);
+    private isRefreshingToken = false;
+    private refreshTokenSubject = new Subject<string | undefined>();
 
     intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
-        if (this.authenticationService.isTokenExpired()) {
-            this.authenticationService.renewToken();
-        }
+        let requestWithAuthentication = request;
 
         const jwt = this.authenticationService.getToken();
-
         if (jwt) {
-            const cloned = request.clone({
-                headers: request.headers.set('Authorization', `Bearer ${jwt}`)
-            });
-
-            return next.handle(cloned);
-        } else {
-            this.authenticationService.unauthenticate();
+            requestWithAuthentication = this.addTokenInHeaders(request, jwt);
         }
 
-        return next.handle(request);
+        return next.handle(requestWithAuthentication)
+            .pipe(
+                catchError(error => {
+                    if (error instanceof HttpErrorResponse && error.status === 401) {
+                        return this.handleAunauthorizedError(request, next, error);
+                    }
+
+                    return throwError(() => error);
+                })
+            );
+    }
+
+    private handleAunauthorizedError(request: HttpRequest<any>, next: HttpHandler, initialError: any): Observable<HttpEvent<any>> {
+        if (!this.isRefreshingToken) {
+            this.isRefreshingToken = true;
+            this.refreshTokenSubject.next(undefined);
+
+            const refreshToken = this.authenticationService.getRefreshToken();
+            if (refreshToken) {
+                const refreshTokenRequest: RefreshTokenRequest = {
+                    refreshTokenValue: refreshToken
+                };
+                this.userRestService.refreshToken(refreshTokenRequest)
+                    .then(refreshTokenResponse => {
+                        this.authenticationService.authenticate(refreshTokenResponse.accessToken, refreshTokenResponse.refreshToken);
+                    })
+                    .catch(() => {
+                        return this.handleNoRefreshToken(initialError);
+                    })
+                    .finally(() => this.isRefreshingToken = false);
+            } else {
+                return this.handleNoRefreshToken(initialError);
+            }
+        }
+
+        return this.refreshTokenSubject.pipe(
+            filter(token => !!token),
+            take(1),
+            switchMap(token => {
+                let requestWithAuthentication = request;
+                if (token) {
+                    requestWithAuthentication = this.addTokenInHeaders(request, token)
+                }
+                return next.handle(requestWithAuthentication);
+            })
+        );
+    }
+
+    private addTokenInHeaders(request: HttpRequest<any>, token: string): HttpRequest<any> {
+        return request.clone({
+            headers: request.headers.set('Authorization', `Bearer ${token}`)
+        });
+    }
+
+    private handleNoRefreshToken(initialError: any): Observable<HttpEvent<any>> {
+        this.router.navigate(['/login']);
+        this.refreshTokenSubject.next(undefined);
+        this.authenticationService.unauthenticate();
+        this.snackBar.open('You are unauthenticated. Please, re-authenticate before retrying your action.', 'Close', { duration: 5000 });
+        return throwError(() => initialError);
     }
 }

frontend/src/app/core/service/authentication.service.ts

@@ -18,7 +18,6 @@ interface UserDetails {
     providedIn: 'root'
 })
 export class AuthenticationService {
-    private userRestService = inject(UserRestService);
 
     authenticate(token: string, refreshToken: string): void {
         localStorage.setItem(JWT_PARAM, token);
@@ -50,6 +49,10 @@ export class AuthenticationService {
         return localStorage.getItem(JWT_PARAM) ?? undefined;
     }
 
+    getRefreshToken(): string | undefined {
+        return localStorage.getItem(REFRESH_TOKEN_PARAM) ?? undefined;
+    }
+
     isTokenExpired(): boolean {
         let result = false;
 
@@ -65,19 +68,6 @@ export class AuthenticationService {
         return result;
     }
 
-    renewToken(): void {
-        const refreshToken = localStorage.getItem(REFRESH_TOKEN_PARAM);
-        if (refreshToken) {
-            const request: RefreshTokenRequest = {
-                refreshTokenValue: refreshToken
-            };
-            this.userRestService.refreshToken(request)
-                .then(refreshTokenResponse => {
-                    this.authenticate(refreshTokenResponse.accessToken, refreshTokenResponse.refreshToken);
-                });
-        }
-    }
-
     private extractUserFromLocalStorage(): User | undefined {
         let result: User | undefined = undefined;