Implemented filter

frontend/src/app/services/games.service.ts

@@ -1,9 +1,11 @@
 import {Injectable} from '@angular/core';
 import {GamesApi} from "../api/GamesApi";
 import {HttpClient} from "@angular/common/http";
-import {map, Observable} from "rxjs";
+import {distinct, map, Observable} from "rxjs";
 import {DetectedGameDto} from "../models/dtos/DetectedGameDto";
 import {GameOverviewDto} from "../models/dtos/GameOverviewDto";
+import {GenreDto} from "../models/dtos/GenreDto";
+import {ThemeDto} from "../models/dtos/ThemeDto";
 
 @Injectable({
   providedIn: 'root'
@@ -42,6 +44,34 @@ export class GamesService implements GamesApi {
     return this.http.get<DetectedGameDto>(`${this.apiPath}/game/${slug}`);
   }
 
+  // TODO: This method of removing duplicates is most certainly an anti-pattern in RxJS
+  // TODO: However, I did not get the 'distinct()' pipe to work properly, so I have to take another look in the future
+  getAvailableGenres(): Observable<GenreDto[]> {
+    return this.getAllGames().pipe(
+      map<DetectedGameDto[], GenreDto[]>(
+        games => {
+          let availableGenresMap: Map<string, GenreDto> = new Map<string, GenreDto>;
+          games.map(game => game.genres === undefined ? [] : game.genres).flat().forEach(genre => availableGenresMap.set(genre.slug, genre));
+          return Array.from(availableGenresMap.values()).sort((g1, g2) => g1.name.localeCompare(g2.name));
+        }
+      )
+    );
+  }
+
+  // TODO: This method of removing duplicates is most certainly an anti-pattern in RxJS
+  // TODO: However, I did not get the 'distinct()' pipe to work properly, so I have to take another look in the future
+  getAvailableThemes(): Observable<ThemeDto[]> {
+    return this.getAllGames().pipe(
+      map<DetectedGameDto[], ThemeDto[]>(
+        games => {
+          let availableThemesMap: Map<string, ThemeDto> = new Map<string, GenreDto>;
+          games.map(game => game.themes === undefined ? [] : game.themes).flat().forEach(theme => availableThemesMap.set(theme.slug, theme));
+          return Array.from(availableThemesMap.values()).sort((t1, t2) => t1.name.localeCompare(t2.name));
+        }
+      )
+    );
+  }
+
   downloadGame(slug: String): void {
     window.open(`v1${this.apiPath}/game/${slug}/download`, '_top');
   }