refactor to use caching interceptor

src/app/http-interceptors/csrf.interceptor.ts

@@ -0,0 +1,29 @@
+import { Injectable } from '@angular/core';
+import { deviceID } from '../api-utils';
+import {
+  HttpInterceptor, HttpHandler, HttpRequest, HttpHeaders
+} from '@angular/common/http';
+
+import { CookieService } from '../cookie.service';
+
+
+@Injectable()
+export class CSRFInterceptor implements HttpInterceptor {
+
+  constructor(private cookieService: CookieService) { }
+
+  intercept(req: HttpRequest<any>, next: HttpHandler) {
+    const dID: String = deviceID();
+    const csrfCookie = 'CSRF-Token-' + dID
+
+    // Clone the request and replace the original headers with
+    // cloned headers, updated with the CSRF information.
+    const csrfReq = req.clone({
+      headers: req.headers.set('X-CSRF-Token-' + dID,
+        this.cookieService.getCookie(csrfCookie))
+    });
+
+    // send cloned request with header to the next handler.
+    return next.handle(csrfReq);
+  }
+}