export const createDataRange = () => {
  let range = [0, 1] as readonly [number, number];

  const eventTarget = new EventTarget();

  const setRange = (newRange: readonly [number, number]) => {
    range = [...newRange];
    eventTarget.dispatchEvent(new CustomEvent('updated', { detail: range }));
  };

  const toDataSpace = (x: number) => {
    const [start, end] = range;
    const width = end - start;
    return x * width + start;
  };

  return {
    setRange,
    toDataSpace,
    eventTarget,
  };
};

export type DataRange = ReturnType<typeof createDataRange>;