// Geometry for the exported PO's left signatory block (cols A-D).
// The approver signature is centred over the name; the company stamp/seal sits to
// its RIGHT with a gap so it never overlays the signature or name — important
// because uploaded signatures/stamps aren't always transparent PNGs.

export interface Size { width: number; height: number }

export interface SignatoryLayout {
  sigLeft: number | null;   // px from the block's left edge, or null when no signature
  stampLeft: number | null; // px from the block's left edge, or null when no stamp
}

export function signatoryLayout(opts: {
  blockPx: number;
  sig: Size | null;
  stamp: Size | null;
  gap?: number;
}): SignatoryLayout {
  const gap = opts.gap ?? 10;
  const sigLeft = opts.sig ? Math.round((opts.blockPx - opts.sig.width) / 2) : null; // centred

  let stampLeft: number | null = null;
  if (opts.stamp) {
    stampLeft =
      sigLeft != null && opts.sig
        ? Math.min(opts.blockPx - opts.stamp.width, sigLeft + opts.sig.width + gap) // clear of the signature
        : opts.blockPx - opts.stamp.width - 6; // no signature → right-align in the block
    stampLeft = Math.max(0, stampLeft);
  }

  return { sigLeft, stampLeft };
}