import argparse
import pathlib
import sys

from PIL import Image

GREEN = (0, 255, 0)
RED = (255, 0, 0)


def generate_coll_map(in_path: str, out_path: str) -> None:
    png = Image.open(in_path).convert("RGB")
    assert png.height % 8 == 0 and png.width % 8 == 0

    out_bytes = []
    bits = []

    for y in range(png.height // 8):
        for x in range(png.width // 8):
            pixel = png.getpixel((x * 8, y * 8))

            bit = None
            if pixel == RED:
                bit = 1
            elif pixel == GREEN:
                bit = 0
            else:
                print(f"unsupported pixel in collision map {pixel}", file=sys.stderr)
                return

            bits.append(bit)
            if len(bits) == 8:
                byte = sum([bit << i for i, bit in enumerate(bits)])
                out_bytes.append(byte)
                bits = []

    lines = []
    for line_no in range(0, len(out_bytes), 16):
        line = out_bytes[line_no : line_no + 16]
        lines.append("    DB " + ", ".join(["$%02X" % b for b in line]))

    section = pathlib.Path(in_path).name.replace("_coll.png", "")
    all_lines = "\n".join(lines)

    with open(out_path, "wb") as outf:
        outf.write(
            f"""SECTION "{section.upper()} MAP", ROM0

; Values are provided in tiles
DEF {section}_width  EQU {png.width // 8}
DEF {section}_height EQU {png.height // 8}

{section}_collision_map::
{all_lines}
""".encode(
                "utf-8"
            )
        )


def main() -> None:
    parser = argparse.ArgumentParser("generate_coll_map")
    parser.add_argument("-o", "--output", required=True)
    parser.add_argument("png")

    args = parser.parse_args()
    generate_coll_map(args.png, args.output)


if __name__ == "__main__":
    main()