main.py

"""FastAPI Backend for OpenNL2SQL - Simplified for HuggingFace Spaces
Author: Amal SP
Created: December 2025
"""

from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from typing import Optional, List, Dict, Any
import os
import logging

# Configure logging
logging.basicConfig(
    level=logging.INFO,
    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s'
)
logger = logging.getLogger(__name__)

# Initialize FastAPI app
app = FastAPI(
    title="OpenNL2SQL API",
    description="AI-powered Natural Language to SQL Analytics System",
    version="1.0.0"
)

# CORS configuration
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Request/Response Models
class QueryRequest(BaseModel):
    question: str
    session_id: Optional[str] = None

class QueryResponse(BaseModel):
    success: bool
    sql: Optional[str] = None
    results: Optional[List[Dict[str, Any]]] = None
    sql_explanation: Optional[str] = None
    results_explanation: Optional[str] = None
    error: Optional[str] = None
    session_id: str

@app.get("/")
async def root():
    """Health check endpoint"""
    return {
        "status": "healthy",
        "service": "OpenNL2SQL API",
        "version": "1.0.0",
        "message": "FastAPI backend is running on Hugging Face Spaces!"
    }

@app.get("/health")
async def health_check():
    """Detailed health check"""
    return {
        "status": "healthy",
        "groq_api_configured": bool(os.getenv("GROQ_API_KEY")),
        "service": "OpenNL2SQL API"
    }

@app.post("/query", response_model=QueryResponse)
async def process_query(request: QueryRequest):
    """Process natural language query"""
    # For now, return a placeholder response
    # This will be integrated with GROQ API and full backend logic
    session_id = request.session_id or "demo-session"
    
    return QueryResponse(
        success=True,
        sql="SELECT * FROM demo_table LIMIT 10;",
        results=[{"status": "Backend is running! Full implementation coming soon."}],
        sql_explanation="This is a demo response. Full NL2SQL functionality will be integrated.",
        results_explanation="The backend is successfully deployed on Hugging Face Spaces.",
        session_id=session_id
    )

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860)