"""Decoupe un fichier answers_<backend>.json en items individuels pour le juge.

Le workflow de jugement (eval/judge_workflow.js) lit un fichier JSON par item.
Pour ne plus ecraser les runs entre backends (PLAN 7.5), chaque backend a son
repertoire : eval/runs/items_<backend>/<id>.json.

Usage :
  python -m eval.split_items eval/runs/answers_mistral.json
  -> eval/runs/items_mistral/{concept-01,...}.json
Puis : Workflow judge_workflow.js avec args {"itemsDir": ".../runs/items_mistral"}.
"""
from __future__ import annotations

import json
import re
import sys
from pathlib import Path


def main() -> int:
    if len(sys.argv) != 2:
        print(__doc__)
        return 1
    src = Path(sys.argv[1])
    data = json.loads(src.read_text(encoding="utf-8"))
    m = re.match(r"answers_(.+)\.json$", src.name)
    backend = m.group(1) if m else src.stem
    out_dir = src.parent / f"items_{backend}"
    out_dir.mkdir(parents=True, exist_ok=True)
    n = 0
    for it in data["items"]:
        keep = {k: it[k] for k in ("id", "category", "prompt", "gold", "answer",
                                   "citations", "code_findings", "deterministic")
                if k in it}
        (out_dir / f"{it['id']}.json").write_text(
            json.dumps(keep, ensure_ascii=False, indent=1), encoding="utf-8")
        n += 1
    print(f"{n} items -> {out_dir}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())