/**
 * Item-equality helpers. 1:1 port of Base UI React's
 * `packages/react/src/internals/itemEquality.ts` — no framework-specific
 * pieces.
 */

export type ItemEqualityComparer<Item = unknown, Value = Item> = (
	itemValue: Item,
	selectedValue: Value,
) => boolean;

export const defaultItemEquality: ItemEqualityComparer = (
	itemValue,
	selectedValue,
) => Object.is(itemValue, selectedValue);

export function compareItemEquality<Item, Value>(
	itemValue: Item,
	selectedValue: Value,
	comparer: ItemEqualityComparer<Item, Value>,
): boolean {
	if (itemValue == null || selectedValue == null) {
		return Object.is(itemValue, selectedValue);
	}
	return comparer(itemValue, selectedValue);
}

export function selectedValueIncludes<Item, Value>(
	selectedValues: readonly Item[] | undefined | null,
	itemValue: Value,
	comparer: ItemEqualityComparer<Value, Item>,
): boolean {
	if (!selectedValues || selectedValues.length === 0) {
		return false;
	}
	return selectedValues.some((selectedValue) => {
		if (selectedValue === undefined) return false;
		return compareItemEquality(itemValue, selectedValue, comparer);
	});
}

export function findItemIndex<Item, Value>(
	itemValues: readonly Item[] | undefined | null,
	selectedValue: Value,
	comparer: ItemEqualityComparer<Item, Value>,
): number {
	if (!itemValues || itemValues.length === 0) {
		return -1;
	}
	return itemValues.findIndex((itemValue) => {
		if (itemValue === undefined) return false;
		return compareItemEquality(itemValue, selectedValue, comparer);
	});
}

export function removeItem<Item, Value>(
	selectedValues: readonly Item[],
	itemValue: Value,
	comparer: ItemEqualityComparer<Value, Item>,
): Item[] {
	return selectedValues.filter(
		(selectedValue) => !compareItemEquality(itemValue, selectedValue, comparer),
	);
}