"""Verify the downloaded handoff without extra packages."""
import hashlib
import json
from pathlib import Path

root = Path(__file__).resolve().parent
manifest = json.loads((root / 'FILES_SHA256.json').read_text())
for relative, info in manifest.items():
    path = root / relative
    if not path.resolve().is_relative_to(root):
        raise SystemExit('Unsafe manifest path: ' + relative)
    if not path.is_file() or path.stat().st_size != info['bytes']:
        raise SystemExit('Missing or wrong size: ' + relative)
    with path.open('rb') as stream:
        actual = hashlib.file_digest(stream, 'sha256').hexdigest()
    if actual != info['sha256']:
        raise SystemExit('SHA256 mismatch: ' + relative)
print(f'PASS: {len(manifest)} files verified; this is a compact results package, not full trajectories or media.')