import uuid
import asyncio
import os

from fastapi import FastAPI, APIRouter, File, UploadFile, Form, HTTPException, BackgroundTasks, status
from fastapi.responses import FileResponse
from starlette.background import BackgroundTask

import aiofiles


router = APIRouter(
    tags=["converter"]
)


@router.post("/")
async def convert(background_tasks: BackgroundTasks, file: UploadFile = File({}), format: str = Form({})):
    temp_uuid = uuid.uuid1()

    temp_filename = str(temp_uuid) + '.fb2'
    converted_temp_filename = str(temp_uuid) + '.' + format

    async with aiofiles.open(temp_filename, 'wb') as f:
        content = await file.read()

        if isinstance(content, str):
            content = content.encode()

        await f.write(content)

    proc = await asyncio.create_subprocess_exec(
        './bin/fb2c', 'convert', '--to', format, temp_filename,
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.PIPE
    )

    await proc.communicate()

    background_tasks.add_task(os.remove, temp_filename)

    if proc.returncode != 0:
        return HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Can't convert!")

    return FileResponse(
        converted_temp_filename,
        background=BackgroundTask(lambda: os.remove(converted_temp_filename))
    )


app = FastAPI()

app.include_router(router)