Sliding session implemented by using jwt interceptor to refresh the token 10 minutes before expiry

overlord/src/app/auth/auth.service.ts

@@ -6,6 +6,9 @@ import {map} from 'rxjs/operators';
 import {User} from '../core/user';
 
 const loginUrl = '/token';
+const refreshUrl = '/refresh';
+const JWT_USER = 'JWT_USER';
+const ACCESS_TOKEN_REFRESH_MINUTES = 10;  // refresh token 10 minutes before expiry
 
 @Injectable({providedIn: 'root'})
 export class AuthService {
@@ -13,7 +16,7 @@ export class AuthService {
   public currentUser: Observable<User>;
 
   constructor(private http: HttpClient) {
-    this.currentUserSubject = new BehaviorSubject<User>(JSON.parse(localStorage.getItem('currentUser')));
+    this.currentUserSubject = new BehaviorSubject<User>(JSON.parse(localStorage.getItem(JWT_USER)));
     this.currentUser = this.currentUserSubject.asObservable();
   }
 
@@ -31,7 +34,7 @@ export class AuthService {
       .pipe(map(u => this.parseJwt(u)))
       .pipe(map(user => {
         // store user details and jwt token in local storage to keep user logged in between page refreshes
-        localStorage.setItem('currentUser', JSON.stringify(user));
+        localStorage.setItem(JWT_USER, JSON.stringify(user));
         this.currentUserSubject.next(user);
         return user;
       }));
@@ -55,9 +58,36 @@ export class AuthService {
     });
   }
 
+  needsRefreshing(): boolean {
+
+    // We use this line to debug token refreshing
+    // console.log("\n", Date.now(), ": Date.now()\n", this.user.exp * 1000, ": user.exp\n",(this.user.exp - (ACCESS_TOKEN_REFRESH_MINUTES * 60)) * 1000, ": comp");
+    return Date.now() > (this.user.exp - (ACCESS_TOKEN_REFRESH_MINUTES * 60)) * 1000;
+  }
+
+  expired(): boolean {
+    return Date.now() > this.user.exp * 1000;
+  }
+
   logout() {
     // remove user from local storage to log user out
-    localStorage.removeItem('currentUser');
+    localStorage.removeItem(JWT_USER);
     this.currentUserSubject.next(null);
   }
+
+  getJwtToken() {
+    return JSON.parse(localStorage.getItem(JWT_USER)).access_token;
+  }
+
+  refreshToken() {
+    return this.http.post<any>(refreshUrl, {})
+      .pipe(map(u => u.access_token))
+      .pipe(map(u => this.parseJwt(u)))
+      .pipe(map(user => {
+        // store user details and jwt token in local storage to keep user logged in between page refreshes
+        localStorage.setItem(JWT_USER, JSON.stringify(user));
+        this.currentUserSubject.next(user);
+        return user;
+      }));
+  }
 }