import uuid
from typing import List, Union, Generator, Tuple

from fastapi import UploadFile
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import Session
from sqlmodel import select, col, desc

from app.core.doc_loaders import doc_loader
from app.exceptions.exception import ResourceNotFoundError
from app.models import File
from app.providers.storage import storage
from app.schemas.common import DeleteResponse
from app.services.file.file import BaseFileService
import json

class OSSFileService(BaseFileService):
    @staticmethod
    def get_file_list_by_ids(*, session: Session, file_ids: List[str]) -> List[File]:
        if not file_ids:
            return []
        statement = select(File).where(col(File.id).in_(json.loads(file_ids)))
        return session.execute(statement).scalars().all()

    @staticmethod
    async def get_file_list(*, session: AsyncSession, purpose: str, file_ids: List[str]) -> List[File]:
        statement = select(File)
        if purpose is not None and len(purpose) > 0:
            statement = statement.where(File.purpose == purpose)
        if file_ids is not None:
            statement = statement.where(File.id.in_(file_ids))
        statement = statement.order_by(desc(File.created_at))
        result = await session.execute(statement)
        return result.scalars().all()

    @staticmethod
    async def create_file(*, session: AsyncSession, purpose: str, file: UploadFile) -> File:
        # 文件是否存在
        # statement = (
        #     select(File)
        #     .where(File.purpose == purpose)
        #     .where(File.filename == file.filename)
        #     .where(File.bytes == file.size)
        # )
        # result = await session.execute(statement)
        # ext_file = result.scalars().first()
        # if ext_file is not None:
        #     # TODO: 文件去重策略
        #     return ext_file

        file_key = f"{uuid.uuid4()}-{file.filename}"
        storage.save(filename=file_key, data=file.file.read())

        # 存储
        db_file = File(purpose=purpose, filename=file.filename, bytes=file.size, key=file_key)
        session.add(db_file)
        await session.commit()
        await session.refresh(db_file)
        return db_file

    @staticmethod
    async def get_file(*, session: AsyncSession, file_id: str) -> File:
        statement = select(File).where(File.id == file_id)
        result = await session.execute(statement)
        ext_file = result.scalars().one_or_none()
        if ext_file is None:
            raise ResourceNotFoundError(message="File not found")
        return ext_file

    @staticmethod
    async def get_file_content(*, session: AsyncSession, file_id: str) -> Tuple[Union[bytes, Generator], str]:
        ext_file = await OSSFileService.get_file(session=session, file_id=file_id)
        file_data = storage.load(ext_file.key)
        return file_data, ext_file.filename

    @staticmethod
    async def delete_file(*, session: AsyncSession, file_id: str) -> DeleteResponse:
        ext_file = await OSSFileService.get_file(session=session, file_id=file_id)
        # TODO 删除s3文件

        # 删除记录
        await session.delete(ext_file)
        await session.commit()
        return DeleteResponse(id=file_id, deleted=True)

    @staticmethod
    def search_in_files(query: str, file_keys: List[str]) -> dict:
        files = {}
        for file_key in file_keys:
            file_data = storage.load(file_key)
            # 截取前 5000 字符，防止超出 LLM 最大上下文限制
            files[file_key] = doc_loader.load(file_data)[:5000]

        return files