range.ts

export function range(
	end: number,
	config?: { step?: number; direction?: "asc" | "desc" },
): Generator<number>;
export function range(
	start: number,
	end: number,
	config?: { step?: number; direction?: "asc" | "desc" },
): Generator<number>;
export function* range(
	startOrEnd: number,
	endOrConfig?: number | { step?: number; direction?: "asc" | "desc" },
	maybeConfig?: { step?: number; direction?: "asc" | "desc" },
) {
	const [start, finalEnd, config] =
		typeof endOrConfig === "number"
			? [startOrEnd, endOrConfig, maybeConfig ?? {}]
			: [0, startOrEnd, endOrConfig ?? {}];

	const { step = 1, direction = "asc" } = config;

	// For desc direction, swap start and end, adjusting for exclusive upper bound
	const [actualStart, actualEnd] =
		direction === "desc" ? [finalEnd - 1, start - 1] : [start, finalEnd];

	const increment = direction === "asc" ? step : -step;

	for (
		let i = actualStart;
		direction === "asc" ? i < actualEnd : i > actualEnd;
		i += increment
	) {
		yield i;
	}
}

export function rangeSync(
	end: number,
	config?: { step?: number; direction?: "asc" | "desc" },
): number[];
export function rangeSync(
	start: number,
	end: number,
	config?: { step?: number; direction?: "asc" | "desc" },
): number[];
export function rangeSync(
	startOrEnd: number,
	endOrConfig?: number | { step?: number; direction?: "asc" | "desc" },
	maybeConfig?: { step?: number; direction?: "asc" | "desc" },
): number[] {
	const [start, finalEnd, config] =
		typeof endOrConfig === "number"
			? [startOrEnd, endOrConfig, maybeConfig ?? {}]
			: [0, startOrEnd, endOrConfig ?? {}];

	return [...range(start, finalEnd, config)];
}