#!/usr/bin/env python3
"""Restore ICW WebDataset shards to split/identity/image.jpg folders."""

from __future__ import annotations

import argparse
import io
import json
import tarfile
from pathlib import Path


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("release", type=Path)
    parser.add_argument("output", type=Path)
    args = parser.parse_args()
    release = args.release.resolve()
    output = args.output.resolve()
    output.mkdir(parents=True, exist_ok=True)

    manifest = json.loads((release / "manifest.json").read_text(encoding="utf-8"))
    restored = 0
    for shard in manifest["shards"]:
        pending_key: str | None = None
        pending_image: bytes | None = None
        with tarfile.open(release / shard["path"], "r:") as archive:
            for member in archive:
                extracted = archive.extractfile(member)
                if extracted is None:
                    raise RuntimeError(f"Cannot read {member.name}")
                key = Path(member.name).stem
                if member.name.endswith(".jpg"):
                    pending_key = key
                    pending_image = extracted.read()
                elif member.name.endswith(".json"):
                    if pending_key != key or pending_image is None:
                        raise RuntimeError(f"Invalid member order near {member.name}")
                    metadata = json.load(extracted)
                    split = str(metadata["split"])
                    identity = str(metadata["identity_id"])
                    image_name = str(metadata["image_filename"])
                    destination = output / split / identity / image_name
                    destination.parent.mkdir(parents=True, exist_ok=True)
                    destination.write_bytes(pending_image)
                    restored += 1
                    pending_key = None
                    pending_image = None
        print(f"restored {shard['path']}")
    print(f"complete: {restored} images restored to {output}")


if __name__ == "__main__":
    main()