#!/usr/bin/python3
import sys
import struct
import PIL.Image
_, inpath, outpath = sys.argv

image = PIL.Image.open(inpath)
assert image.mode == "RGBA", "image mode is "+image.mode

# We measure width and height prior to the rotation
width, height = image.width, image.height

image = image.transpose(PIL.Image.Transpose.ROTATE_270)

with open(outpath, "wb") as out:
    out.write(struct.pack("=HH", width, height))
    for channel in "BGRA":
        pixelbytes = image.getchannel(channel).tobytes()
        def rlegroups():
            curpixel=None
            count=0
            litrun = b""
            for pixel in pixelbytes:
                if curpixel is None:
                    curpixel = pixel
                    count = 1
                elif curpixel != pixel:
                    assert count > 0
                    if count <= 2:
                        if len(litrun)+count > 127:
                            assert len(litrun) > 0
                            yield litrun
                            litrun = b""
                        litrun += bytes([curpixel]) * count
                    else:
                        if litrun != b"":
                            assert len(litrun) > 0
                            yield litrun
                            litrun = b""
                        yield (curpixel, count)
                    curpixel = pixel
                    count = 1
                else:
                    count += 1
            if litrun != b"":
                assert len(litrun) > 0
                yield litrun
            if count > 0:
                yield (curpixel, count)
        for group in rlegroups():
            if type(group) == bytes:
                out.write(struct.pack("=B", len(group)+128) + group)
            else:
                pixel, count = group
                assert count > 0
                if count >= 128:
                    out.write(struct.pack("=BIB", 0, count, pixel))
                else:
                    out.write(struct.pack("=BB", count, pixel))