#!/usr/bin/env python3

# Pre-release iPhone OS 1 iBoots used some weird formats for storing graphics,
# this script is meant to decode Apple logo found on prototype iPod touch 1
# that ran iBoot-115.6 which is a good ole SwitchBoard gear, but with blood
#
# This particular example is more or less just RGBA, but long sequences
# of same color are TLV encoded
#
# The format was likely just meant to be temporary, and provides almost no metadata,
# even width & height are hardcoded into the iBoot itself

import sys
import struct
from PIL import Image

WIDTH = 71
HEIGHT = 84

def main():
    try:
        _, file, out = sys.argv
    except ValueError:
        print("usage: %s <input> <output>" % sys.argv[0])
        exit(-1)

    with open(file, "rb") as f:
        buf = f.read()
        image_len = len(buf)

    if buf[:4] != b"rgba":
        print("not \"rgba\" image!")
        exit(-1)

    image = Image.new("RGBA", (WIDTH, HEIGHT), None)

    off = 4
    curr_x = 0
    curr_y = 0

    while True:
        if off >= image_len:
            break

        if buf[off] == 0x13 and buf[off + 1] == 0x57:
            fill_len = struct.unpack("<H", buf[off + 2 : off + 2 + 2])[0]
            off += 4
        else:
            fill_len = 1

        r, g, b, a = struct.unpack("BBBB", buf[off : off + 4])
        off += 4

        fill_len_cnt = 0

        while -fill_len != fill_len_cnt:
            image.putpixel((curr_x, curr_y), (r, g, b, a))
            fill_len_cnt -= 1

            curr_x += 1
            if curr_x == WIDTH:
                curr_y += 1
                curr_x = 0

    with open(out, "wb") as f:
        image.save(f, "png")

if __name__ == "__main__":
    main()