Add frontend.

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

@@ -0,0 +1,73 @@
+import { Injectable } from "@angular/core";
+import { User } from "../model/User";
+
+const JWT_PARAM = 'jwt';
+
+interface UserDetails {
+    sub: string;
+    exp: number;
+    email: string;
+    pseudo: string;
+    roles: string;
+}
+
+@Injectable({
+    providedIn: 'root'
+})
+export class AuthenticationService {
+    authenticate(token: string): void {
+        localStorage.setItem(JWT_PARAM, token);
+    }
+
+    unauthenticate(): void {
+        localStorage.removeItem(JWT_PARAM);
+    }
+    
+    isAuthenticated(): boolean {
+        let result = false;
+
+        const userDetails = this.extractUserDetails();
+        
+        if (userDetails) {
+            const authenticationExpiration = new Date(userDetails.exp * 1000);
+            result = authenticationExpiration > new Date();
+        }
+
+        return result;
+    }
+
+    private extractUserFromLocalStorage(): User | undefined {
+        let result: User | undefined = undefined;
+
+        const userDetails = this.extractUserDetails();
+        if (userDetails) {
+            const user = this.convertToUser(userDetails);
+            result = user;
+        }
+
+        return result;
+    }
+
+    private extractUserDetails(): UserDetails | undefined {
+        let result: UserDetails | undefined = undefined;
+
+        const token = localStorage.getItem(JWT_PARAM);
+
+        const tokenParts = token?.split('.');
+        if (tokenParts?.length === 3 && tokenParts[1].length) {
+            const userDetails: UserDetails = JSON.parse(tokenParts[1]);
+            result = userDetails;
+        }
+
+        return result;
+    }
+
+    private convertToUser(userDetails: UserDetails): User {
+        return {
+            id: userDetails.sub,
+            email: userDetails.email,
+            pseudo: userDetails.pseudo,
+            roles: userDetails.roles.split(',')
+        };
+    }
+}