Initial commit

components/collections/CollectionSelectionProvider.tsx

@@ -0,0 +1,43 @@
+"use client";
+import { createContext, useCallback, useContext, useMemo, useState } from "react";
+
+type Ctx = {
+  ids: Set<number>;
+  has: (id: number) => boolean;
+  toggle: (id: number) => void;
+  setMany: (ids: number[]) => void;
+  clear: () => void;
+};
+
+const CollectionSelectCtx = createContext<Ctx | null>(null);
+
+export function CollectionSelectionProvider({ children }: { children: React.ReactNode }) {
+  const [ids, setIds] = useState<Set<number>>(new Set());
+
+  const toggle = useCallback((id: number) => {
+    setIds((cur) => {
+      const next = new Set(cur);
+      if (next.has(id)) next.delete(id); else next.add(id);
+      return next;
+    });
+  }, []);
+
+  const setMany = useCallback((newIds: number[]) => setIds(new Set(newIds)), []);
+  const clear = useCallback(() => setIds(new Set()), []);
+
+  const value = useMemo<Ctx>(() => ({
+    ids,
+    has: (id) => ids.has(id),
+    toggle,
+    setMany,
+    clear,
+  }), [ids, toggle, setMany, clear]);
+
+  return <CollectionSelectCtx.Provider value={value}>{children}</CollectionSelectCtx.Provider>;
+}
+
+export function useCollectionSelection() {
+  const ctx = useContext(CollectionSelectCtx);
+  if (!ctx) throw new Error("useCollectionSelection must be used within CollectionSelectionProvider");
+  return ctx;
+}