feat: playback speed options

hooks/usePlaybackSpeed.ts

@@ -0,0 +1,45 @@
+import type { BaseItemDto } from "@jellyfin/sdk/lib/generated-client";
+import { useMemo } from "react";
+import type { Settings } from "@/utils/atoms/settings";
+
+/**
+ * Determines the appropriate playback speed for a media item based on a three-tier priority system:
+ * 1. Media-specific speed (highest priority)
+ * 2. Series-specific speed (medium priority)
+ * 3. Default speed (lowest priority)
+ */
+const usePlaybackSpeed = (
+  item: BaseItemDto | null,
+  settings: Settings | null,
+): { readonly playbackSpeed: number } => {
+  const playbackSpeed = useMemo(() => {
+    if (!settings || !item) {
+      return 1.0;
+    }
+
+    // Start with the lowest priority: default playback speed
+    let selectedPlaybackSpeed = settings.defaultPlaybackSpeed;
+
+    // Second priority: use what is set for Series if it is a Series
+    if (item.SeriesId && settings.playbackSpeedPerShow[item.SeriesId]) {
+      selectedPlaybackSpeed = settings.playbackSpeedPerShow[item.SeriesId];
+    }
+
+    // Highest priority: use what is set for Media if it is set
+    if (item.Id && settings.playbackSpeedPerMedia[item.Id] !== undefined) {
+      selectedPlaybackSpeed = settings.playbackSpeedPerMedia[item.Id];
+    }
+
+    return selectedPlaybackSpeed;
+  }, [
+    item?.Id,
+    item?.SeriesId,
+    settings?.defaultPlaybackSpeed,
+    settings?.playbackSpeedPerMedia,
+    settings?.playbackSpeedPerShow,
+  ]);
+
+  return { playbackSpeed };
+};
+
+export default usePlaybackSpeed;