Added foundation of a simple mock-api

apps/dafa-web/src/app/services/api/participants.service.ts

@@ -0,0 +1,45 @@
+import { HttpClient } from '@angular/common/http';
+import { Injectable } from '@angular/core';
+import { environment } from '@dafa-environment';
+import { Participant } from '@dafa-models/participant.model';
+import { SortBy } from '@dafa-models/sort-by.model';
+import { BehaviorSubject, combineLatest, Observable } from 'rxjs';
+import { map } from 'rxjs/operators';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class ParticipantsService {
+  private _participants$: Observable<Participant[]> = this.httpClient.get<Participant[]>(
+    `${environment.apiBase}/participants`
+  );
+  private _sortBy$ = new BehaviorSubject<SortBy | null>({ key: 'service', reverse: false });
+  public sortBy$: Observable<SortBy> = this._sortBy$.asObservable();
+
+  public participants$: Observable<Participant[]> = combineLatest([this._sortBy$, this._participants$]).pipe(
+    map(([sortBy, participants]) => {
+      if (sortBy) {
+        const reverse = sortBy.reverse ? -1 : 1;
+        return [...participants].sort((a, b) => {
+          const first = a[sortBy.key];
+          const second = b[sortBy.key];
+          return reverse * +(first > second) - +(second > first);
+        });
+      }
+      return participants;
+    })
+  );
+
+  public setSortKey(key: keyof Participant) {
+    const currentSortBy = this._sortBy$.getValue();
+    let reverse = false;
+
+    if (currentSortBy?.key === key) {
+      reverse = !currentSortBy.reverse;
+    }
+
+    this._sortBy$.next({ key, reverse });
+  }
+
+  constructor(private httpClient: HttpClient) {}
+}