Add search publication page and fix category access

frontend/src/app/pages/search-publications/search-publications.service.ts

@@ -0,0 +1,49 @@
+import { inject, Injectable } from "@angular/core";
+import { PublicationRestService } from "../../core/rest-services/publications/publication.rest-service";
+import { BehaviorSubject, Observable } from "rxjs";
+import { Publication } from "../../core/rest-services/publications/model/publication";
+import { MatSnackBar } from "@angular/material/snack-bar";
+
+
+@Injectable()
+export class SearchPublicationsService {
+    private publicationRestService = inject(PublicationRestService);
+    private publicationsSubject = new BehaviorSubject<Publication[]>([]);
+    private isLoadingSubject = new BehaviorSubject<boolean>(false);
+    private isLoadedSubject = new BehaviorSubject<boolean>(false);
+    private snackBar = inject(MatSnackBar);
+
+    get publications$(): Observable<Publication[]> {
+        return this.publicationsSubject.asObservable();
+    }
+    
+    get isLoading$(): Observable<boolean> {
+        return this.isLoadingSubject.asObservable();
+    }
+
+    get isLoaded$(): Observable<boolean> {
+        return this.isLoadedSubject.asObservable();
+    }
+
+    loadPublications(searchCriteria: string): void {
+         this.isLoadingSubject.next(true);
+         this.isLoadedSubject.next(false);
+         this.publicationsSubject.next([]);
+
+         this.publicationRestService.search(searchCriteria)
+            .then(publications => {
+                this.publicationsSubject.next(publications);
+            })
+            .catch(error => {
+                if (error.status !== 404) {
+                    const errorMessage = 'An error occured while retrieving publications.';
+                    console.error(errorMessage, error);
+                    this.snackBar.open(errorMessage, 'Close', { duration: 5000 });
+                }
+            })
+            .finally(() => {
+                this.isLoadingSubject.next(false);
+                this.isLoadedSubject.next(true);
+            });
+    }
+}