From 4f50ec6665198a1af991f827c74760a3aa25c0fc Mon Sep 17 00:00:00 2001
From: Uruk <contact@uruk.dev>
Date: Thu, 21 May 2026 23:49:23 +0200
Subject: [PATCH] feat(casting): add useCastSelection hook

---
 hooks/useCastSelection.ts | 75 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 hooks/useCastSelection.ts

diff --git a/hooks/useCastSelection.ts b/hooks/useCastSelection.ts
new file mode 100644
index 000000000..fb466b65b
--- /dev/null
+++ b/hooks/useCastSelection.ts
@@ -0,0 +1,75 @@
+/**
+ * Source of truth for the active cast track / quality / version selection.
+ *
+ * Truth = the CastSelection echoed back in the cast media customData. A local
+ * `pending` selection is shown optimistically while a reload re-transcodes, then
+ * cleared once the cast reports it (reconciled) or the reload fails.
+ */
+
+import type { BaseItemDto } from "@jellyfin/sdk/lib/generated-client";
+import { useCallback, useEffect, useState } from "react";
+import type { MediaStatus } from "react-native-google-cast";
+import { resolveSelection, selectionsEqual } from "@/utils/casting/selection";
+import type { CastSelection } from "@/utils/casting/types";
+
+interface UseCastSelectionParams {
+  currentItem: BaseItemDto | null;
+  mediaStatus: MediaStatus | null | undefined;
+  /** Reload the cast stream with the given selection. Resolves true on success. */
+  reload: (selection: CastSelection) => Promise<boolean>;
+}
+
+interface UseCastSelectionResult {
+  /** Effective selection: optimistic pending, else cast truth, else default. */
+  currentSelection: CastSelection | null;
+  /** Merge a partial selection, show it optimistically, and reload the stream. */
+  applySelection: (partial: Partial<CastSelection>) => void;
+}
+
+export const useCastSelection = ({
+  currentItem,
+  mediaStatus,
+  reload,
+}: UseCastSelectionParams): UseCastSelectionResult => {
+  const [pending, setPending] = useState<CastSelection | null>(null);
+
+  // Truth: the selection the cast reports as loaded, via customData.
+  const truth =
+    (
+      mediaStatus?.mediaInfo?.customData as
+        | { selection?: CastSelection }
+        | undefined
+    )?.selection ?? null;
+
+  const currentSelection: CastSelection | null =
+    pending ??
+    truth ??
+    (currentItem ? resolveSelection(currentItem, {}) : null);
+
+  // A new media item invalidates any pending selection from the previous one.
+  // biome-ignore lint/correctness/useExhaustiveDependencies: keyed on item id only
+  useEffect(() => {
+    setPending(null);
+  }, [currentItem?.Id]);
+
+  // Reconcile: once the cast reports the pending selection as loaded, clear it.
+  useEffect(() => {
+    if (pending && truth && selectionsEqual(pending, truth)) {
+      setPending(null);
+    }
+  }, [pending, truth]);
+
+  const applySelection = useCallback(
+    (partial: Partial<CastSelection>) => {
+      if (!currentSelection) return;
+      const next: CastSelection = { ...currentSelection, ...partial };
+      setPending(next);
+      reload(next).then((ok) => {
+        if (!ok) setPending(null);
+      });
+    },
+    [currentSelection, reload],
+  );
+
+  return { currentSelection, applySelection };
+};