#!/usr/bin/env python3
"""Download one M4Raw Brain examination from Hugging Face."""

from __future__ import annotations

import argparse
import csv
from pathlib import Path

from huggingface_hub import hf_hub_download


REPO_ID = "mylyu/M4Raw_brain"
MANIFESTS = {
    "T1": "metadata/T1_manifest.tsv",
    "T2": "metadata/T2_manifest.tsv",
    "FLAIR": "metadata/FLAIR_manifest.tsv",
    "GRE": "metadata/GRE_manifest.tsv",
}
REP_FIELDS = tuple(f"h5_rep{index:02d}" for index in range(1, 7))


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("scan_id")
    parser.add_argument("--sequence", choices=tuple(MANIFESTS), required=True)
    parser.add_argument("--output", type=Path, default=Path("M4Raw_case"))
    parser.add_argument("--repo-id", default=REPO_ID)
    parser.add_argument("--revision", default="v1.6.0")
    parser.add_argument(
        "--include-gre",
        action="store_true",
        help="Also download GRE for an original-cohort T1/T2/FLAIR examination.",
    )
    return parser.parse_args()


def download(repo_id: str, revision: str, filename: str, output: Path) -> Path:
    return Path(
        hf_hub_download(
            repo_id=repo_id,
            repo_type="dataset",
            revision=revision,
            filename=filename,
            local_dir=output,
        )
    )


def manifest_row(path: Path, scan_id: str) -> dict[str, str]:
    with path.open(newline="", encoding="utf-8") as handle:
        rows = [
            row
            for row in csv.DictReader(handle, delimiter="\t")
            if row["scan_id"] == scan_id
        ]
    if len(rows) != 1:
        raise RuntimeError(
            f"Expected one manifest row for {scan_id}, found {len(rows)}"
        )
    return rows[0]


def paths_for_sequence(args: argparse.Namespace, sequence: str) -> list[str]:
    manifest_name = MANIFESTS[sequence]
    local_manifest = download(args.repo_id, args.revision, manifest_name, args.output)
    row = manifest_row(local_manifest, args.scan_id)
    return [manifest_name, *(row[field] for field in REP_FIELDS if row.get(field))]


def main() -> None:
    args = parse_args()
    if args.include_gre and args.sequence == "GRE":
        raise SystemExit("--include-gre is unnecessary with --sequence GRE")
    args.output.mkdir(parents=True, exist_ok=True)
    paths = paths_for_sequence(args, args.sequence)
    if args.include_gre:
        paths.extend(paths_for_sequence(args, "GRE"))
    unique_paths = list(dict.fromkeys(paths))
    for filename in unique_paths:
        print(download(args.repo_id, args.revision, filename, args.output))
    print(f"Downloaded {len(unique_paths)} files for {args.scan_id}")


if __name__ == "__main__":
    main()