Add statistics pages - move data service and add ds-loading

src/app/core/statistics/usage-report-data.service.ts

@@ -0,0 +1,62 @@
+import { HttpClient } from '@angular/common/http';
+import { Injectable } from '@angular/core';
+import { Store } from '@ngrx/store';
+import { NotificationsService } from '../../shared/notifications/notifications.service';
+import { dataService } from '../cache/builders/build-decorators';
+import { RemoteDataBuildService } from '../cache/builders/remote-data-build.service';
+import { ObjectCacheService } from '../cache/object-cache.service';
+import { CoreState } from '../core.reducers';
+import { HALEndpointService } from '../shared/hal-endpoint.service';
+import { DataService } from '../data/data.service';
+import { RequestService } from '../data/request.service';
+import { DefaultChangeAnalyzer } from '../data/default-change-analyzer.service';
+import { USAGE_REPORT } from './models/usage-report.resource-type';
+import { UsageReport } from './models/usage-report.model';
+import { Observable } from 'rxjs';
+import { getRemoteDataPayload, getSucceededRemoteData } from '../shared/operators';
+import { map } from 'rxjs/operators';
+
+/**
+ * A service to retrieve {@link UsageReport}s from the REST API
+ */
+@Injectable()
+@dataService(USAGE_REPORT)
+export class UsageReportService extends DataService<UsageReport> {
+
+  protected linkPath = 'statistics/usagereports';
+
+  constructor(
+    protected comparator: DefaultChangeAnalyzer<UsageReport>,
+    protected halService: HALEndpointService,
+    protected http: HttpClient,
+    protected notificationsService: NotificationsService,
+    protected objectCache: ObjectCacheService,
+    protected rdbService: RemoteDataBuildService,
+    protected requestService: RequestService,
+    protected store: Store<CoreState>,
+  ) {
+    super();
+  }
+
+  getStatistic(scope: string, type: string): Observable<UsageReport> {
+    return this.findById(`${scope}_${type}`).pipe(
+      getSucceededRemoteData(),
+      getRemoteDataPayload(),
+    );
+  }
+
+  searchStatistics(uri: string, page: number, size: number): Observable<UsageReport[]> {
+    return this.searchBy('object', {
+      searchParams: [{
+        fieldName: `uri`,
+        fieldValue: uri,
+      }],
+      currentPage: page,
+      elementsPerPage: size,
+    }).pipe(
+      getSucceededRemoteData(),
+      getRemoteDataPayload(),
+      map((list) => list.page),
+    );
+  }
+}