feat(downloads): add media quality and queue reordering

src/utils/queueOrdering.ts

@@ -0,0 +1,61 @@
+export interface QueueOrderItem {
+  id: string;
+}
+
+/**
+ * Move the selected rows as one block into an insertion position among the
+ * unselected rows. The position is intentionally defined after selection is
+ * removed so callers can use the same semantics for UI and backend queues.
+ */
+export const moveSelectedBlockToIndex = <T extends QueueOrderItem>(
+  items: T[],
+  selectedIds: ReadonlySet<string> | readonly string[],
+  targetIndex: number
+): T[] => {
+  const selected = selectedIds instanceof Set ? selectedIds : new Set(selectedIds);
+  const selectedItems = items.filter(item => selected.has(item.id));
+  const unselectedItems = items.filter(item => !selected.has(item.id));
+  const insertionIndex = Math.max(0, Math.min(targetIndex, unselectedItems.length));
+
+  return [
+    ...unselectedItems.slice(0, insertionIndex),
+    ...selectedItems,
+    ...unselectedItems.slice(insertionIndex)
+  ];
+};
+
+/**
+ * Convert a pointer boundary in the original list to the insertion index
+ * used by moveSelectedBlockToIndex. A boundary is between rows and ranges
+ * from 0 (before the first row) through items.length (after the last row).
+ */
+export const targetIndexForBoundary = <T extends QueueOrderItem>(
+  items: T[],
+  selectedIds: ReadonlySet<string> | readonly string[],
+  boundaryIndex: number
+): number => {
+  const selected = selectedIds instanceof Set ? selectedIds : new Set(selectedIds);
+  const boundary = Math.max(0, Math.min(boundaryIndex, items.length));
+  return items
+    .slice(0, boundary)
+    .reduce((count, item) => count + (selected.has(item.id) ? 0 : 1), 0);
+};
+
+/**
+ * Translate a desired local order to the backend's registered-only queue.
+ * Staged rows are not registered with the backend, so they must not affect
+ * the target index sent over IPC.
+ */
+export const targetIndexForDesiredOrder = <T extends QueueOrderItem>(
+  currentItems: T[],
+  selectedIds: ReadonlySet<string> | readonly string[],
+  desiredItems: T[]
+): number => {
+  const selected = selectedIds instanceof Set ? selectedIds : new Set(selectedIds);
+  const currentIds = new Set(currentItems.map(item => item.id));
+  const firstSelectedIndex = desiredItems.findIndex(item => selected.has(item.id));
+  if (firstSelectedIndex === -1) return currentItems.filter(item => !selected.has(item.id)).length;
+  return desiredItems
+    .slice(0, firstSelectedIndex)
+    .reduce((count, item) => count + (selected.has(item.id) || !currentIds.has(item.id) ? 0 : 1), 0);
+};