import { formatSliderValueWithUnit } from "../slider/slider-value";

const signedNumberPattern = "[-−]?\\d+(?:[.,]\\d+)?";
const rangePairPattern = new RegExp(
  `(${signedNumberPattern})(?:\\s*[\\p{L}%°]+)?\\s*(?:/|[-‐‑‒–—−])\\s*(${signedNumberPattern})`,
  "u",
);

export function formatRangeSliderValue(
  value: readonly number[],
  step: number,
  unit?: string,
): string {
  const formatValue = (item: number): string =>
    formatSliderValueWithUnit(item, step, unit);

  if (value.length >= 2 && value[0] === value[1]) {
    return formatValue(value[0] ?? 0);
  }

  return value.map(formatValue).join(" – ");
}

export function snapRangeSliderValue(
  value: number,
  {
    max,
    min,
    step,
  }: {
    max: number;
    min: number;
    step: number;
  },
): number {
  const clampedValue = Math.min(max, Math.max(min, value));
  const steppedValue = Math.round((clampedValue - min) / step) * step + min;

  return Number(steppedValue.toFixed(4));
}

export function parseRangeSliderDraft(
  draftValue: string,
  {
    max,
    min,
    step,
  }: {
    max: number;
    min: number;
    step: number;
  },
): [number, number] | null {
  const pairMatch = draftValue.match(rangePairPattern);
  const values = pairMatch
    ? [pairMatch[1], pairMatch[2]]
        .map((match) => parseRangeSliderDraftNumber(match))
        .filter(Number.isFinite)
    : Array.from(
        draftValue.matchAll(/[-−]?\d+(?:[.,]\d+)?/g),
        ([match]) => parseRangeSliderDraftNumber(match),
      ).filter(Number.isFinite);

  if (values.length === 0) {
    return null;
  }

  const [first = min, second = first] = values;
  const sortedValues = [
    snapRangeSliderValue(first, { max, min, step }),
    snapRangeSliderValue(second, { max, min, step }),
  ].sort((left, right) => left - right) as [number, number];

  return sortedValues;
}

function parseRangeSliderDraftNumber(value: string | undefined): number {
  return Number(value?.replace("−", "-").replace(",", "."));
}