import json
import re
import shutil
from datetime import datetime
from pathlib import Path


ROOT = Path("/mnt/nas/zhangyiming/database/rlbench/train")
JSON_DIR = ROOT / "json"
BACKUP_DIR = ROOT / "json_bak_pic_num"


FRONT_RE = re.compile(r"front_(\d+)\.png$")


def is_training_json(path: Path) -> bool:
    if path.name.endswith("_statistics.json"):
        return False
    if path.name == "train_statistics.json":
        return False
    return path.suffix == ".json"


def get_pic_num(front_pic: str, cache: dict[Path, int]) -> int:
    pic_path = Path(front_pic)
    episode_dir = pic_path.parent
    if episode_dir in cache:
        return cache[episode_dir]

    max_idx = None
    for image_path in episode_dir.glob("front_*.png"):
        match = FRONT_RE.match(image_path.name)
        if match:
            idx = int(match.group(1))
            max_idx = idx if max_idx is None else max(max_idx, idx)

    if max_idx is None:
        raise FileNotFoundError(f"No front_*.png images found in {episode_dir}")

    cache[episode_dir] = max_idx
    return max_idx


def main() -> None:
    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
    backup_dir = BACKUP_DIR / timestamp
    backup_dir.mkdir(parents=True, exist_ok=False)

    image_count_cache = {}
    processed = {}

    for json_path in sorted(JSON_DIR.glob("*.json")):
        if not is_training_json(json_path):
            continue

        backup_path = backup_dir / json_path.name
        shutil.copy2(json_path, backup_path)

        with json_path.open("r", encoding="utf-8") as f:
            records = json.load(f)

        for record in records:
            if "front_pic" not in record:
                raise KeyError(f"{json_path} has a record without front_pic")
            record["pic_num"] = get_pic_num(record["front_pic"], image_count_cache)

        tmp_path = json_path.with_suffix(".json.tmp")
        with tmp_path.open("w", encoding="utf-8") as f:
            json.dump(records, f, ensure_ascii=False, indent=2)
        tmp_path.replace(json_path)

        processed[json_path.name] = len(records)

    summary_path = backup_dir / "pic_num_update_summary.json"
    with summary_path.open("w", encoding="utf-8") as f:
        json.dump(
            {
                "backup_dir": str(backup_dir),
                "processed": processed,
            },
            f,
            ensure_ascii=False,
            indent=2,
        )

    print(json.dumps({"backup_dir": str(backup_dir), "processed": processed}, ensure_ascii=False, indent=2))


if __name__ == "__main__":
    main()