/** period_index is 1-based (Sem 1 … Sem N). */
export function ganttSpan(
  activeIndexes: number[],
  periodCount: number,
): { leftPct: number; widthPct: number; first: number; last: number } | null {
  const n = Number(periodCount) || 0;
  const idxs = activeIndexes.filter((i) => Number.isFinite(i) && i >= 1 && (n <= 0 || i <= n));
  if (!idxs.length || n <= 0) return null;
  const first = Math.min(...idxs);
  const last = Math.max(...idxs);
  return {
    first,
    last,
    leftPct: ((first - 1) / n) * 100,
    widthPct: ((last - first + 1) / n) * 100,
  };
}

export function periodHasAmount(
  periods: { period_id?: number; period_index?: number; amount?: number }[],
  week: { id: number; period_index: number },
): number {
  const slot = periods.find((x) => x.period_index === week.period_index || x.period_id === week.id);
  return Number(slot?.amount || 0);
}

export function periodHasConceptBar(
  periods: { period_index?: number; start_pct?: number; end_pct?: number }[],
  week: { period_index: number },
): { start_pct: number; end_pct: number } | null {
  const slot = periods.find((x) => x.period_index === week.period_index);
  if (!slot) return null;
  const start = Number(slot.start_pct || 0);
  const end = Number(slot.end_pct || 0);
  if (start === 0 && end === 0) return null;
  return { start_pct: start, end_pct: Math.max(start, end) };
}