#!/usr/bin/env python3
from __future__ import annotations

import struct
import sys
from pathlib import Path


def main() -> int:
    if len(sys.argv) != 3:
        raise SystemExit("usage: png-to-icns ICONSET_DIR OUTPUT.icns")
    iconset = Path(sys.argv[1])
    output = Path(sys.argv[2])
    resources = [
        (b"icp4", "icon_16x16.png"),
        (b"icp5", "icon_32x32.png"),
        (b"icp6", "icon_32x32@2x.png"),
        (b"ic07", "icon_128x128.png"),
        (b"ic08", "icon_256x256.png"),
        (b"ic09", "icon_512x512.png"),
        (b"ic10", "icon_512x512@2x.png"),
    ]
    blocks: list[bytes] = []
    for resource_type, filename in resources:
        payload = (iconset / filename).read_bytes()
        blocks.append(resource_type + struct.pack(">I", len(payload) + 8) + payload)
    body = b"".join(blocks)
    output.write_bytes(b"icns" + struct.pack(">I", len(body) + 8) + body)
    return 0


if __name__ == "__main__":
    raise SystemExit(main())