import os
import sys

from PIL import Image

from palette import intensity_to_index

def convert(image, bpp):
    assert bpp in {8, 4, 2, 1}, bpp
    px_per_byte = 8 // bpp
    px_per_row = 8
    bits_per_byte = 8
    bytes_per_row = (px_per_row // (bits_per_byte // bpp))

    assert image.mode in {'L', '1'}, image.mode
    width, height = image.size

    buf = bytearray(width * height // px_per_byte)

    for cell_y in range(height//8):
        for cell_x in range(width//8):
            for y in range(8):
                for x in range(8):
                    px = image.getpixel((cell_x * 8 + x, cell_y * 8 + y))
                    if image.mode == 'L':
                        index = intensity_to_index(px)
                    elif image.mode == '1':
                        index = int(px != 0)
                    buf_ix = x//px_per_byte + (bytes_per_row * (cell_x * 8 + (cell_y * width) + y))
                    buf[buf_ix] |= (index << bpp * ((px_per_byte - 1) - (x % px_per_byte)))
    return buf

def debug(buf, bpp):
    assert bpp in {8, 4, 2, 1}, bpp
    px_per_byte = 8 // bpp
    px_per_row = 8
    bits_per_byte = 8
    bytes_per_row = (px_per_row // (bits_per_byte // bpp))
    bit_mask = (2 ** bpp) - 1

    for row in range(len(buf) // bytes_per_row):
        for x in range(bytes_per_row):
            px = buf[row * bytes_per_row + x]
            for shift in reversed(range(0, px_per_row, bpp)):
                print((px >> shift) & bit_mask, end='')
        print()
        if (row % 8 == 7):
            print()

bpp = int(sys.argv[1])
out_path = sys.argv[2]
assert len(sys.argv) >= 4, sys.argv

with open(out_path, 'wb') as f:
    for in_path in sys.argv[3:]:
        im = Image.open(in_path)
        buf = convert(im, bpp)
        if 'NBPP_DEBUG' in os.environ:
            debug(buf, bpp)
        f.write(buf)