app.py

# app.py
import os
import logging
from fastapi import FastAPI, HTTPException
from fastapi.responses import JSONResponse
from pydantic import BaseModel
from huggingface_hub import InferenceClient
from typing import Optional

# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Initialize FastAPI app
app = FastAPI(
    title="LLM Chat API",
    description="API for getting chat responses from Llama model",
    version="1.0.0"
)

class ChatRequest(BaseModel):
    text: str

class ChatResponse(BaseModel):
    response: str
    status: str

def llm_chat_response(text: str) -> str:
    try:
        HF_TOKEN = os.getenv("HF_TOKEN")
        logger.info("Checking HF_TOKEN...")
        if not HF_TOKEN:
            logger.error("HF_TOKEN not found in environment variables")
            raise HTTPException(status_code=500, detail="HF_TOKEN not configured")
        
        logger.info("Initializing InferenceClient...")
        client = InferenceClient(token=HF_TOKEN)
        
        logger.info("Sending request to model...")
        # Using text-generation endpoint instead of chat
        response = client.text_generation(
            text + str(' describe in one line only'),
            model="meta-llama/Llama-3.2-11B-Vision-Instruct",
            max_new_tokens=500,
            temperature=0.7
        )
        return response

    except Exception as e:
        logger.error(f"Error in llm_chat_response: {str(e)}")
        raise HTTPException(status_code=500, detail=str(e))

@app.post("/chat", response_model=ChatResponse)
async def chat(request: ChatRequest):
    try:
        logger.info(f"Received chat request with text: {request.text}")
        response = llm_chat_response(request.text)
        return ChatResponse(response=response, status="success")
    except HTTPException as he:
        logger.error(f"HTTP Exception in chat endpoint: {str(he)}")
        raise he
    except Exception as e:
        logger.error(f"Unexpected error in chat endpoint: {str(e)}")
        raise HTTPException(status_code=500, detail=str(e))

@app.get("/")
async def root():
    return {"message": "Welcome to the LLM Chat API. Use POST /chat endpoint to get responses."}

@app.exception_handler(404)
async def not_found_handler(request, exc):
    return JSONResponse(
        status_code=404,
        content={"error": "Endpoint not found. Please use POST /chat for queries."}
    )

@app.exception_handler(405)
async def method_not_allowed_handler(request, exc):
    return JSONResponse(
        status_code=405,
        content={"error": "Method not allowed. Please check the API documentation."}
    )