// Tiny PNG / JPEG headers for the image checks (imageInfo reads only the header). Shared by the tests.

/** PNG header imageInfo reads: signature + IHDR (+ optional tRNS) + IEND, padded to `pad` bytes. */
export function png(w: number, h: number, o: { colorType?: number; depth?: number; trns?: boolean; pad?: number } = {}): Uint8Array {
  const chunks = 8 + 25 + (o.trns ? 14 : 0) + 12;
  const b = new Uint8Array(Math.max(chunks, o.pad ?? 0));
  b.set([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
  const dv = new DataView(b.buffer);
  dv.setUint32(8, 13); b.set([0x49, 0x48, 0x44, 0x52], 12); dv.setUint32(16, w); dv.setUint32(20, h);
  b[24] = o.depth ?? 8; b[25] = o.colorType ?? 2;
  let p = 33;
  if (o.trns) { dv.setUint32(p, 2); b.set([0x74, 0x52, 0x4e, 0x53], p + 4); p += 14; }
  dv.setUint32(p, 0); b.set([0x49, 0x45, 0x4e, 0x44], p + 4);
  return b;
}

/** JPEG with an APP0 segment and a baseline SOF0 frame header. */
export function jpeg(w: number, h: number, pad = 0): Uint8Array {
  const head = [0xff, 0xd8, 0xff, 0xe0, 0, 16, 0x4a, 0x46, 0x49, 0x46, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0,
    0xff, 0xc0, 0, 17, 8, h >> 8, h & 255, w >> 8, w & 255, 3, 1, 0x22, 0, 2, 0x11, 1, 3, 0x11, 1, 0xff, 0xd9];
  const b = new Uint8Array(Math.max(head.length, pad));
  b.set(head);
  return b;
}