Main view improvements

Frontend/src/app/interceptors/loader.interceptor.ts

@@ -0,0 +1,42 @@
+import { Injectable } from '@angular/core';
+import {
+  HttpRequest,
+  HttpHandler,
+  HttpEvent,
+  HttpInterceptor
+} from '@angular/common/http';
+import { finalize, Observable } from 'rxjs';
+import { DataService } from '../services/data.service';
+
+@Injectable()
+export class LoaderInterceptor implements HttpInterceptor {
+
+  private tasks: number = 0;
+
+  constructor(
+    private _data: DataService
+  ) { }
+
+  intercept(request: HttpRequest<unknown>, next: HttpHandler): Observable<HttpEvent<unknown>> {
+    this.addTask();
+    return next.handle(request).pipe(
+      finalize(() => {
+        this.removeTask();
+      })
+    );
+  }
+
+  addTask() {
+    this.tasks++;
+    if (this.tasks === 1) {
+      this._data.showLoader.next(true);
+    }
+  }
+
+  removeTask() {
+    this.tasks--;
+    if (this.tasks === 0) {
+      this._data.showLoader.next(false);
+    }
+  }
+}