"""Backup Aether data dir to HF Dataset as latest-backup.tar.gz.

Tar-gzips AETHER_BACKUP_DIR contents into a temp file and uploads to the
Dataset repo, replacing latest-backup.tar.gz. A timestamped copy is also
kept under history/ for the most recent ~30 backups (older are pruned).
"""
import os
import sys
import tarfile
import tempfile
from datetime import datetime, timezone
from pathlib import Path

from huggingface_hub import HfApi
from huggingface_hub.utils import RepositoryNotFoundError

token = os.environ["HF_TOKEN"]
repo_id = os.environ["AETHER_BACKUP_REPO"]
src_dir = Path(os.environ.get("AETHER_BACKUP_DIR", "/opt/aether/data"))
keep_history = int(os.environ.get("AETHER_BACKUP_KEEP_COUNT", "30"))
filename_latest = os.environ.get("AETHER_BACKUP_LATEST_NAME", "latest-backup.tar.gz")

if not src_dir.exists() or not any(src_dir.iterdir()):
    print(f"aether-backup: src {src_dir} empty, skip", file=sys.stderr)
    sys.exit(0)

api = HfApi(token=token)
ts = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
tmpdir = Path(tempfile.mkdtemp(prefix="aether-backup-"))
archive_path = tmpdir / f"aether-backup-{ts}.tar.gz"

with tarfile.open(archive_path, "w:gz") as tar:
    tar.add(src_dir, arcname=src_dir.name)

print(f"aether-backup: created archive {archive_path} ({archive_path.stat().st_size} bytes)", file=sys.stderr)

# upload as latest
api.upload_file(
    path_or_fileobj=str(archive_path),
    path_in_repo=filename_latest,
    repo_id=repo_id,
    repo_type="dataset",
    commit_message=f"backup {ts}",
)
# also keep timestamped history
hist_path = f"history/aether-backup-{ts}.tar.gz"
api.upload_file(
    path_or_fileobj=str(archive_path),
    path_in_repo=hist_path,
    repo_id=repo_id,
    repo_type="dataset",
    commit_message=f"backup history {ts}",
)
print(f"aether-backup: uploaded {filename_latest} and {hist_path}", file=sys.stderr)

# prune old history
try:
    files = api.list_repo_files(repo_id=repo_id, repo_type="dataset")
    history_files = sorted(f for f in files if f.startswith("history/aether-backup-"))
    overflow = history_files[:-keep_history] if len(history_files) > keep_history else []
    for old in overflow:
        try:
            api.delete_file(
                path_in_repo=old,
                repo_id=repo_id,
                repo_type="dataset",
                commit_message=f"prune {old}",
            )
            print(f"aether-backup: pruned {old}", file=sys.stderr)
        except Exception as exc:
            print(f"aether-backup: prune {old} failed: {exc}", file=sys.stderr)
except RepositoryNotFoundError:
    pass

# cleanup
try:
    archive_path.unlink(missing_ok=True)
    tmpdir.rmdir()
except Exception:
    pass