/*
 * Portions of this file are based on code from react-spectrum.
 * Apache License Version 2.0, Copyright 2020 Adobe.
 *
 * Credits to the React Spectrum team:
 * https://github.com/adobe/react-spectrum/blob/22cb32d329e66c60f55d4fc4025d1d44bb015d71/packages/@react-stately/collections/src/getItemCount.ts
 */

import type { CollectionNode } from "./types";

const cache = new WeakMap<Iterable<unknown>, number>();

export function getItemCount(collection: Iterable<CollectionNode>): number {
	let count = cache.get(collection);
	if (count != null) {
		return count;
	}

	count = 0;
	for (const item of collection) {
		if (item.type === "item") {
			count++;
		}
	}

	cache.set(collection, count);
	return count;
}