export type ImageScaleMode = 'contain' | 'cover' | 'fill'

export function readImageScaleMode(cfg: Record<string, unknown> | undefined | null): ImageScaleMode {
  const v = String(cfg?.scaleMode ?? cfg?.ScaleMode ?? 'contain')
    .trim()
    .toLowerCase()
  if (v === 'cover' || v === 'fill') return v
  return 'contain'
}

export function computeImageDrawRect(
  boxW: number,
  boxH: number,
  sourceW: number,
  sourceH: number,
  scaleMode: string,
): { dx: number; dy: number; dw: number; dh: number } {
  const mode = String(scaleMode ?? 'contain').trim().toLowerCase()
  if (sourceW <= 0 || sourceH <= 0 || mode === 'fill') {
    return { dx: 0, dy: 0, dw: boxW, dh: boxH }
  }
  const ratio =
    mode === 'cover'
      ? Math.max(boxW / sourceW, boxH / sourceH)
      : Math.min(boxW / sourceW, boxH / sourceH)
  const dw = Math.max(1, Math.round(sourceW * ratio))
  const dh = Math.max(1, Math.round(sourceH * ratio))
  return {
    dx: Math.round((boxW - dw) / 2),
    dy: Math.round((boxH - dh) / 2),
    dw,
    dh,
  }
}