#!/usr/bin/env python3
"""Write SHA256SUMS.txt for all published regular files."""

from __future__ import annotations

import argparse
import hashlib
from pathlib import Path


def digest(path: Path) -> str:
    h = hashlib.sha256()
    with path.open("rb") as f:
        for block in iter(lambda: f.read(8 * 1024 * 1024), b""):
            h.update(block)
    return h.hexdigest()


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--release-root", type=Path, required=True)
    ap.add_argument("--output", type=Path)
    args = ap.parse_args()
    out = args.output or args.release_root / "SHA256SUMS.txt"
    paths = []
    for p in args.release_root.rglob("*"):
        if not p.is_file() or p == out or p.name.endswith(".partial"):
            continue
        paths.append(p)
    paths.sort(key=lambda p: p.relative_to(args.release_root).as_posix())
    with out.open("w", encoding="utf-8") as f:
        for p in paths:
            f.write(f"{digest(p)}  {p.relative_to(args.release_root).as_posix()}\n")
    print(f"wrote {len(paths)} checksums to {out}")
    return 0


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