export type Pooled<T> = {
	size: number;
	mask: number;
	cursor: number;
	buffer: Array<T>;
};

export function createRingBuffer<T extends object>(
	size: number,
	create: () => T,
): Pooled<T> {
	if ((size & (size - 1)) !== 0) {
		throw new Error("size must be a power of two");
	}

	const buffer = new Array<T>(size);
	for (let i = 0; i < size; i++) {
		buffer[i] = create();
	}

	return {
		size,
		mask: size - 1,
		cursor: 0,
		buffer,
	};
}

export function claim<T>(pooled: Pooled<T>): T {
	const slot = pooled.buffer[pooled.cursor];
	pooled.cursor = (pooled.cursor + 1) & pooled.mask;

	return slot;
}