from typing import Tuple
from PIL import Image
import sys


def main(font_name, n_glyphs, fname_png, fname_c):
    glyphs = load_glyphs(fname_png)
    assert(len(glyphs) == n_glyphs), f"must be exactly {n_glyphs} glyphs"

    with open(fname_c, "wt") as output:
        output.writelines([
            "// generated code! be nice!\n",
            "#include \"sys/sys.h\";\n",
            f"sys_glyph {font_name}[{n_glyphs}] = {{{', '.join(str(g) for g in glyphs)}}};\n"
        ])


def load_glyphs(fname_png: str):
    with Image.open(fname_png) as im:
        width = im.width
        height = im.height

        assert width % 8 == 0, "width must be a multiple of 8"
        assert height % 8 == 0, "height must be a multiple of 8"

        data = list(im.convert("RGBA").getdata())
        monochrome = [pixel_to_monochrome(p) for p in data]

        glyphs = []
        for gy in range(0, height, 8):
            for gx in range(0, width, 8):
                glyph = 0
                for py in range(0, 8):
                    for px in range(0, 8):
                        x = gx + px
                        y = gy + py
                        if monochrome[y * width + x]:
                            glyph |= 1 << (py * 8 + px)
                glyphs.append(glyph)

        return glyphs


def pixel_to_monochrome(rgba: Tuple[int, int, int, int]):
    if rgba[3] < 128: return False
    if (rgba[0] + rgba[1] + rgba[2])/3 < 128: return False
    return True


if __name__ == "__main__":
    assert len(sys.argv) == 5, \
        "there must be four args (font name, n glyphs, src png, out c)"
    main(sys.argv[1], int(sys.argv[2]), sys.argv[3], sys.argv[4])