"""Download and verify public RefSeg-CA artifacts using Python's standard library."""
from pathlib import Path
import argparse, gzip, hashlib, json, shutil, tarfile, urllib.request
ROOT = Path(__file__).resolve().parents[1]
REPO = 'Ethosoft/RefSeg-CA'


def fetch(base, name, cache, manifest):
    out = cache / name; out.parent.mkdir(parents=True, exist_ok=True)
    expected = manifest['files'][name]['sha256']
    if not out.exists() or hashlib.sha256(out.read_bytes()).hexdigest() != expected:
        tmp = out.with_suffix(out.suffix + '.part')
        with urllib.request.urlopen(base + '/' + name, timeout=120) as r, tmp.open('wb') as f:
            shutil.copyfileobj(r, f)
        assert hashlib.sha256(tmp.read_bytes()).hexdigest() == expected, name + ': checksum mismatch'
        tmp.replace(out)
    return out


def extract(path, dest):
    with tarfile.open(path) as archive:
        for m in archive.getmembers():
            target = (dest / m.name).resolve()
            if not m.isfile() or not target.is_relative_to(dest.resolve()):
                raise ValueError('Unsafe archive member: ' + m.name)
            target.parent.mkdir(parents=True, exist_ok=True)
            with archive.extractfile(m) as source, target.open('wb') as out:
                shutil.copyfileobj(source, out)


def main():
    ap = argparse.ArgumentParser(); ap.add_argument('--revision', default='r3-data-v1')
    ap.add_argument('--synthetic', action='store_true'); a = ap.parse_args()
    base = f'https://huggingface.co/datasets/{REPO}/resolve/{a.revision}'
    with urllib.request.urlopen(base + '/DATA_MANIFEST.json', timeout=60) as r: manifest = json.load(r)
    cache = ROOT / 'build/downloads'; cache.mkdir(parents=True, exist_ok=True)
    extract(fetch(base, 'results/primary-and-review-metrics.tar.gz', cache, manifest), ROOT)
    for name in ['rich_synthetic', 'rich_scenes']:
        p = fetch(base, 'manifests/' + name + '.jsonl.gz', cache, manifest)
        out = ROOT / 'data' / (name + '.jsonl'); out.parent.mkdir(parents=True, exist_ok=True)
        with gzip.open(p, 'rb') as r, out.open('wb') as f: shutil.copyfileobj(r, f)
    if a.synthetic:
        for seed in manifest['seeds']:
            extract(fetch(base, f'archives/rich-seed-{seed}.tar.gz', cache, manifest), ROOT)
    print(json.dumps({'status': 'DOWNLOADED_AND_VERIFIED', 'revision': a.revision, 'synthetic_images': a.synthetic}))


if __name__ == '__main__': main()