import os
from fastapi import FastAPI, HTTPException, Path, APIRouter
from fastapi.responses import FileResponse
from service.file_service import UPLOAD_ROOT

router = APIRouter(
    prefix="/api/file",
    tags=["文件管理"]
)


@router.get("/download/{relative_path:path}", summary="下载文件")
async def download_file(
        relative_path: str = Path(..., description="文件的相对路径")
):
    file_path = os.path.abspath(os.path.join(UPLOAD_ROOT, relative_path))

    if not os.path.exists(file_path):
        raise HTTPException(status_code=404, detail=f"文件不存在: {file_path}")

    if not os.path.isfile(file_path):
        raise HTTPException(status_code=400, detail="路径指向的不是文件")

    if not file_path.startswith(os.path.abspath(UPLOAD_ROOT)):
        raise HTTPException(status_code=403, detail="无权访问该文件")

    return FileResponse(
        path=file_path,
        filename=os.path.basename(file_path),
        media_type="application/octet-stream"
    )