/** Clamps `value` into `[lo, hi]`. When `lo > hi` (e.g. a popup wider than the screen) `lo` wins. */
export function clamp(value: number, lo: number, hi: number): number {
  return Math.max(lo, Math.min(hi, value));
}

/** Whole-pixel top offset that centres an item of `itemHeight` inside `containerHeight`. */
export function centreY(containerHeight: number, itemHeight: number): number {
  return Math.round((containerHeight - itemHeight) / 2);
}

/** Decimal places a number field shows unless it asks for its own (`NumberFieldOptions.decimals`). */
export const NUMBER_DECIMALS = 3;

/**
 * Rounds to `decimals` places and drops trailing zeros: `100`, `0.5`, `9.091`. A value that rounds
 * to zero never carries a minus sign.
 */
export function formatNumber(value: number, decimals = NUMBER_DECIMALS): string {
  const text = value.toFixed(decimals);
  const trimmed = text.includes('.') ? text.replace(/\.?0+$/, '') : text;
  return trimmed === '-0' ? '0' : trimmed;
}

/** Rounds to `decimals` places, which also removes binary-float noise (0.1 × 3 = 0.30000000000000004). */
export function roundTo(value: number, decimals = NUMBER_DECIMALS): number {
  return Number.isFinite(value) ? Number(value.toFixed(decimals)) : value;
}

/**
 * Rounds `value` onto the grid of `stepSize`, so scrubbing lands on clean values even though
 * pointer deltas are fractional.
 */
export function snapToStep(value: number, stepSize: number): number {
  if (!(stepSize > 0) || !Number.isFinite(value)) return value;
  return roundTo(Math.round(value / stepSize) * stepSize);
}

/**
 * Zoom multiplier for one wheel event. Exponential, so scrolling up and back down by the same
 * amount lands exactly where it started. The caller clamps into its own range.
 */
export function zoomFactor(deltaY: number): number {
  return Math.exp(-deltaY * 0.0015);
}

export function formatBytes(bytes: number): string {
  if (bytes >= 1024 * 1024) return `${(bytes / 1024 / 1024).toFixed(1)} MB`;
  // A small sprite is a few hundred bytes, and "0 KB" reads like a broken file.
  return bytes >= 1024 ? `${Math.round(bytes / 1024)} KB` : `${bytes} B`;
}