New: Show downloading status for series progress bar

Closes #5474

frontend/src/Series/Index/createSeriesQueueDetailsSelector.ts

@@ -0,0 +1,42 @@
+import { createSelector } from 'reselect';
+
+export interface SeriesQueueDetails {
+  count: number;
+  episodesWithFiles: number;
+}
+
+function createSeriesQueueDetailsSelector(
+  seriesId: number,
+  seasonNumber?: number
+) {
+  return createSelector(
+    (state) => state.queue.details.items,
+    (queueItems) => {
+      return queueItems.reduce(
+        (acc: SeriesQueueDetails, item) => {
+          if (item.seriesId !== seriesId) {
+            return acc;
+          }
+
+          if (seasonNumber != null && item.seasonNumber !== seasonNumber) {
+            return acc;
+          }
+
+          acc.count++;
+
+          if (item.episodeHasFile) {
+            acc.episodesWithFiles++;
+          }
+
+          return acc;
+        },
+        {
+          count: 0,
+          episodesWithFiles: 0,
+        }
+      );
+    }
+  );
+}
+
+export default createSeriesQueueDetailsSelector;