/**
 * Central binary (1024) data-size formatting for the UI.
 *
 * - Use formatBinaryDataSizeBytes for raw byte counts (files, RAG totals, …).
 * - Use formatBinaryDataSizeFromMebibytes for API fields stored as MB (mebibytes), e.g. maxDataVolumeMB.
 */

const BINARY_BASE = 1024;
const BINARY_UNITS = ['B', 'KB', 'MB', 'GB', 'TB'] as const;

function _maxFractionDigits(value: number): number {
  if (value >= 100 || Number.isInteger(value)) return 0;
  if (value >= 10) return 1;
  return 2;
}

/**
 * Human-readable size from a byte count; picks B … TB automatically (1024-based).
 */
export function formatBinaryDataSizeBytes(bytes: number, localeId = 'de-CH'): string {
  if (!Number.isFinite(bytes)) return '—';
  if (bytes < 0) return '—';
  if (bytes === 0) return `0 ${BINARY_UNITS[0]}`;

  const rawExp = Math.floor(Math.log(bytes) / Math.log(BINARY_BASE));
  const exp = Math.max(0, Math.min(BINARY_UNITS.length - 1, rawExp));
  const value = bytes / BINARY_BASE ** exp;
  const maxFrac = _maxFractionDigits(value);
  const formatted = new Intl.NumberFormat(localeId, {
    maximumFractionDigits: maxFrac,
    minimumFractionDigits: 0,
  }).format(value);
  return `${formatted} ${BINARY_UNITS[exp]}`;
}

/**
 * Same as formatBinaryDataSizeBytes, but input is mebibytes (API convention for plan limits).
 */
export function formatBinaryDataSizeFromMebibytes(mebibytes: number, localeId = 'de-CH'): string {
  if (!Number.isFinite(mebibytes) || mebibytes < 0) return '—';
  if (mebibytes === 0) return `0 ${BINARY_UNITS[0]}`;
  return formatBinaryDataSizeBytes(mebibytes * BINARY_BASE * BINARY_BASE, localeId);
}