ItemSelectionProvider: promote toot expansion

state

* used in Profile, TrendTimelinePanel,
  TimelinePanel

src/timelines/toots/ItemSelectionProvider.ts

@@ -0,0 +1,35 @@
+import {
+  createContext,
+  createSelector,
+  createSignal,
+  useContext,
+  type Accessor,
+} from "solid-js";
+
+export type ItemSelectionState<T> = [(value: T) => boolean, (value: T) => void];
+
+const ItemSelectionContext = /* @__PURE__ */ createContext<
+  ItemSelectionState<any>
+>([() => false, () => undefined]);
+
+export function createSingluarItemSelection<T extends {}>(
+  intial?: T,
+): readonly [Accessor<T | undefined>, ItemSelectionState<T | undefined>] {
+  const [value, setValue] = createSignal<T | undefined>(intial);
+
+  const select = createSelector(value, (a, b) =>
+    typeof b !== "undefined" ? a === b : false,
+  );
+
+  const toggle = (v: T | undefined) => {
+    setValue((o) => (o ? undefined : v));
+  };
+
+  return [value, [select, toggle]];
+}
+
+export function useItemSelection() {
+  return useContext(ItemSelectionContext);
+}
+
+export default ItemSelectionContext.Provider;