from pathlib import Path
from typing import Any

from fastapi import UploadFile
from app.config import get_settings
from app.core.logging import logger

settings = get_settings()


async def upload_dataset(file: UploadFile) -> dict[str, Any]:
    """保存上传文件并检测格式。"""
    upload_dir = settings.uploads_dir
    upload_dir.mkdir(parents=True, exist_ok=True)

    file_path = upload_dir / file.filename
    content = await file.read()
    file_path.write_bytes(content)

    fmt = _detect_format(file.filename or "")
    logger.info(f"Uploaded dataset: {file_path} (format={fmt})")
    return {"path": str(file_path), "format": fmt, "size": len(content)}


def _detect_format(filename: str) -> str:
    ext = Path(filename).suffix.lower().lstrip(".")
    if ext in ("jsonl", "csv", "parquet", "json"):
        return ext
    return "unknown"