/**
 * Maps a horizontal swipe delta to a cycle direction. A leftward swipe (negative
 * dx) advances to the next pairing (+1); a rightward swipe (positive dx) goes to
 * the previous (-1). Movement below the threshold is ignored (0).
 *
 * @param dx - Horizontal travel in px (end minus start).
 * @param threshold - Minimum absolute travel in px to count as a swipe.
 * @returns +1 (next), -1 (previous), or 0 (no cycle).
 */
export function swipeDirection(dx: number, threshold: number): -1 | 0 | 1 {
    if (dx <= -threshold) {
        return 1;
    }
    if (dx >= threshold) {
        return -1;
    }
    return 0;
}