"""Extract the SEL Parquet snapshot into raw records for sel prepare."""

import argparse
import hashlib
import json
import re
import tempfile
from pathlib import Path

import pyarrow.parquet as pq

SPLITS = ("train", "val", "test")
IMAGE_EXTENSIONS = {".png", ".jpg", ".jpeg", ".webp"}


def materialize(snapshot: Path, output: Path) -> None:
    output = output.resolve()
    if output.exists():
        raise FileExistsError(output)
    output.parent.mkdir(parents=True, exist_ok=True)
    with tempfile.TemporaryDirectory(dir=output.parent) as temporary:
        root = Path(temporary) / "records"
        root.mkdir()
        for split in SPLITS:
            previous_index = -1
            dataset = pq.ParquetFile(snapshot / "data" / f"{split}.parquet")
            with (root / f"{split}.jsonl").open("w", encoding="utf-8") as manifest:
                for batch in dataset.iter_batches(batch_size=32):
                    for row in batch.to_pylist():
                        rid = row["id"]
                        if not re.fullmatch(rf"{split}-[0-9]+", rid):
                            raise ValueError(f"Invalid row ID: {rid}")
                        if row["original_index"] <= previous_index or row["split"] != split:
                            raise ValueError(f"Unexpected split or order for {rid}")
                        previous_index = row["original_index"]
                        directory = root / split / rid
                        directory.mkdir(parents=True)
                        record = json.loads(row["record_json"])
                        if image := row["image"]:
                            name, data = image["path"], image["bytes"]
                            if Path(name).name != name or Path(name).suffix not in IMAGE_EXTENSIONS:
                                raise ValueError(f"Invalid image filename: {name}")
                            if name != record.get("source_image"):
                                raise ValueError(f"Image record mismatch for {rid}")
                            if hashlib.sha256(data).hexdigest() != row["source_image_sha256"]:
                                raise ValueError(f"Image checksum mismatch for {rid}")
                            (directory / name).write_bytes(data)
                        artifact = directory / "example.json"
                        artifact.write_text(json.dumps(record, ensure_ascii=False) + "\n", encoding="utf-8")
                        entry = {
                            "artifact_path": artifact.relative_to(root).as_posix(),
                            "task_id": row["task_id"],
                            "selection_mode": row["selection_mode"],
                            "query_first": row["query_first"],
                            "environment_prompt": row["environment_prompt"],
                        }
                        manifest.write(json.dumps(entry, ensure_ascii=False) + "\n")
            print(f"Materialized {split}: {dataset.metadata.num_rows:,} records")
        root.rename(output)


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("snapshot", type=Path)
    parser.add_argument("output", type=Path)
    args = parser.parse_args()
    materialize(args.snapshot, args.output)