Début d'ajout pour la gestion du login

Front/skydivelogs-app/src/services/auth-guard.service.ts

@@ -0,0 +1,23 @@
+import { Injectable } from '@angular/core';
+import { CanActivate, Router, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';
+import { AuthenticationService } from './authentication.service';
+
+@Injectable({ providedIn: 'root' })
+export class AuthGuardService implements CanActivate {
+  constructor(
+    private router: Router,
+    private authenticationService: AuthenticationService
+  ) { }
+
+  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
+    const currentUser = this.authenticationService.currentUserValue;
+    if (currentUser) {
+      // logged in so return true
+      return true;
+    }
+
+    // not logged in so redirect to login page with the return url
+    this.router.navigate(['/login'], { queryParams: { returnUrl: state.url } });
+    return false;
+  }
+}