added interceptor for http calls

src/app/app.module.ts

 import { NgModule } from '@angular/core';
 import { BrowserModule } from '@angular/platform-browser';
+import { HTTP_INTERCEPTORS } from '@angular/common/http';
+
 
 import { AppRoutingModule } from './app-routing.module';
 import { AppComponent } from './app.component';
 import { HeaderComponent } from './shared/components/header/header.component';
+import { HttpInterceptorService } from './shared/interceptors/http-interceptor.service';
 
 @NgModule({
   declarations: [
@@ -14,7 +17,7 @@ import { HeaderComponent } from './shared/components/header/header.component';
     BrowserModule,
     AppRoutingModule
   ],
-  providers: [],
+  providers: [{ provide: HTTP_INTERCEPTORS, useClass: HttpInterceptorService, multi: true },],
   bootstrap: [AppComponent]
 })
 export class AppModule { }

src/app/config/api-config.ts

+import { environment } from "src/environment/environment";
+
+export const apiConfig = {
+    
+    apiBaseUrl: environment.baseURL,
+    // eslint-disable-next-line max-len
+    token: '',
+    catalog:{
+        getCatalog:{
+            'api-url': environment.backendURL + 'catalog',
+        }
+    }
+}
\ No newline at end of file

src/app/shared/interceptors/http-interceptor.service.spec.ts

+import { TestBed } from '@angular/core/testing';
+
+import { HttpInterceptorService } from './http-interceptor.service';
+
+describe('HttpInterceptorService', () => {
+  let service: HttpInterceptorService;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({});
+    service = TestBed.inject(HttpInterceptorService);
+  });
+
+  it('should be created', () => {
+    expect(service).toBeTruthy();
+  });
+});

src/app/shared/interceptors/http-interceptor.service.ts

+import { Injectable } from '@angular/core';
+import {
+  HttpErrorResponse, HttpEvent, HttpHandler, HttpInterceptor,
+  HttpRequest,
+  HttpResponse
+} from '@angular/common/http';
+import { Observable } from 'rxjs';
+import { environment } from 'src/environment/environment';
+import { apiConfig } from 'src/app/config/api-config';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class HttpInterceptorService implements HttpInterceptor{
+
+  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
+
+    // if the system is not in production, change the bearer for each http request
+    if (!environment.production) {
+      const modifiedReq = req.clone({ 
+        headers: req.headers.set('Authorization', `Bearer ${apiConfig.token}`),
+      });
+      return next.handle(modifiedReq);
+    }
+    
+    // if there is nothing to intercept, pass the request.
+    return next.handle(req);
+  }
+}

src/environment/environment.ts

+export const environment = {
+    // local with session
+    production: false,
+    baseURL: 'http://localhost:8888/',
+    backendURL: "",
+    isDebugMode: true
+
+
+}
\ No newline at end of file