#!/usr/bin/env python3
"""Verify final paper-output checksums."""

from __future__ import annotations

import hashlib
from pathlib import Path


ROOT = Path(__file__).resolve().parents[1]
MANIFEST = ROOT / "artifacts" / "manifests" / "paper_outputs.sha256"


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


def main() -> None:
    issues: list[str] = []
    for line_no, line in enumerate(MANIFEST.read_text(encoding="utf-8").splitlines(), start=1):
        if not line.strip():
            continue
        try:
            expected, rel = line.split(None, 1)
        except ValueError:
            issues.append(f"bad checksum line {line_no}: {line!r}")
            continue
        path = ROOT / rel.strip()
        if not path.exists():
            issues.append(f"missing output listed in checksum manifest: {rel}")
            continue
        actual = sha256(path)
        if actual != expected:
            issues.append(f"checksum mismatch for {rel}: expected {expected}, got {actual}")

    if issues:
        print("Paper-output checksum check failed:")
        for issue in issues:
            print(f"- {issue}")
        raise SystemExit(1)
    print("Paper-output checksum check passed.")


if __name__ == "__main__":
    main()