export function getOrientation(arrayBuffer: ArrayBuffer): number {
  try {
    const view = new DataView(arrayBuffer);

    if (view.getUint16(0, false) !== 0xFFD8) {
      return 1;
    }

    let offset = 2;
    const length = view.byteLength;

    while (offset < length) {
      if (view.getUint16(offset + 2, false) <= 8) return 1;
      const marker = view.getUint16(offset, false);
      offset += 2;

      if (marker === 0xFFE1) {
        const exifOffset = offset + 10;
        if (exifOffset > length) return 1;

        const little = view.getUint16(exifOffset, false) === 0x4949;
        offset += 4 + view.getUint32(exifOffset + 4, little);

        const tags = view.getUint16(offset, little);
        offset += 2;

        for (let i = 0; i < tags; i++) {
          const tagOffset = offset + (i * 12);
          if (view.getUint16(tagOffset, little) === 0x0112) {
            return view.getUint16(tagOffset + 8, little);
          }
        }
      } else if ((marker & 0xFF00) !== 0xFF00) {
        break;
      } else {
        offset += view.getUint16(offset, false);
      }
    }
  } catch (error) {
    console.warn("Could not read EXIF orientation, using default:", error);
  }
  return 1;
}

export function applyOrientation(
  ctx: CanvasRenderingContext2D,
  orientation: number,
  width: number,
  height: number,
) {
  switch (orientation) {
    case 2:
      ctx.transform(-1, 0, 0, 1, width, 0);
      break;
    case 3:
      ctx.transform(-1, 0, 0, -1, width, height);
      break;
    case 4:
      ctx.transform(1, 0, 0, -1, 0, height);
      break;
    case 5:
      ctx.transform(0, 1, 1, 0, 0, 0);
      break;
    case 6:
      ctx.transform(0, 1, -1, 0, height, 0);
      break;
    case 7:
      ctx.transform(0, -1, -1, 0, height, width);
      break;
    case 8:
      ctx.transform(0, -1, 1, 0, 0, width);
      break;
    default:
      break;
  }
}