import asyncio 
from concurrent.futures import ThreadPoolExecutor
from fastapi import FastAPI, UploadFile, File
from cnn_pipeline.pipeline import classify_tumor
from contextlib import asynccontextmanager


async def lifespan(app: FastAPI):
    yield # The app  is running at this point 
    executor.shutdown()


app = FastAPI(title="Brain Tumor CNN Service",lifespan=lifespan)

# its okay to use thead pool (prototype level) as pytorch surpasses GIL 
executor=ThreadPoolExecutor(max_workers=2)


@app.post("/classify")
async def classify(file: UploadFile = File(...)):

    # read the fiel content 
    image_bytes = await file.read()
    
    # get the event Loop 
    loop = asyncio.get_running_loop()
    
    
    result = await loop.run_in_executor(executor, classify_tumor, image_bytes)
    
    return result