Ajout d'un système de cache des

requêtes HTTP

Front/skydivelogs-app/src/services/caching-interceptor.service.ts

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+import { Injectable } from "@angular/core";
+import {
+  HttpEvent,
+  HttpRequest,
+  HttpResponse,
+  HttpInterceptor,
+  HttpHandler
+} from "@angular/common/http";
+
+import { Observable } from "rxjs/Observable";
+import { startWith, tap } from "rxjs/operators";
+import "rxjs/add/observable/of";
+
+import { RequestCache } from "./request-cache.service";
+
+@Injectable()
+export class CachingInterceptor implements HttpInterceptor {
+  constructor(private cache: RequestCache) {}
+
+  intercept(req: HttpRequest<any>, next: HttpHandler) {
+    const cachedResponse = this.cache.get(req);
+    return cachedResponse
+      ? Observable.of(cachedResponse)
+      : this.sendRequest(req, next);
+  }
+
+  sendRequest(
+    req: HttpRequest<any>,
+    next: HttpHandler
+  ): Observable<HttpEvent<any>> {
+    return next.handle(req).pipe(
+      tap(event => {
+        if (event instanceof HttpResponse) {
+          this.cache.put(req, event);
+        }
+      })
+    );
+  }
+}