app/main.py

"""
Main FastAPI Application
=========================
Application entry point
"""

import logging
from contextlib import asynccontextmanager
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import JSONResponse

from app.core.config import settings
from app.core.exceptions import ToxicDetectionException
from app.models.model_loader import model_loader
from app.api.routes import router


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


@asynccontextmanager
async def lifespan(app: FastAPI):
    """
    Lifespan events
    
    Startup: Load model
    Shutdown: Cleanup
    """
    # Startup
    logger.info("Starting up...")
    try:
        logger.info("Loading model...")
        model_loader.load()
        logger.info("Model loaded successfully")
    except Exception as e:
        logger.error(f"Failed to load model: {str(e)}")
        # Continue anyway - health endpoint will show model not loaded
    
    yield
    
    # Shutdown
    logger.info("Shutting down...")


# Create FastAPI app
app = FastAPI(
    title=settings.API_TITLE,
    description=settings.API_DESCRIPTION,
    version=settings.API_VERSION,
    lifespan=lifespan,
    docs_url="/docs",
    redoc_url="/redoc",
    openapi_url="/openapi.json"
)

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


# Exception handlers
@app.exception_handler(ToxicDetectionException)
async def toxic_detection_exception_handler(request, exc: ToxicDetectionException):
    """Handle custom exceptions"""
    return JSONResponse(
        status_code=exc.status_code,
        content={
            "success": False,
            "error": exc.detail,
            "detail": None
        }
    )


@app.exception_handler(Exception)
async def general_exception_handler(request, exc: Exception):
    """Handle general exceptions"""
    logger.error(f"Unhandled exception: {str(exc)}", exc_info=True)
    return JSONResponse(
        status_code=500,
        content={
            "success": False,
            "error": "Internal server error",
            "detail": str(exc) if settings.LOG_LEVEL == "DEBUG" else None
        }
    )


# Include routers
app.include_router(router, prefix="/api/v1", tags=["v1"])
app.include_router(router, prefix="", tags=["root"])


# For direct run
if __name__ == "__main__":
    import uvicorn
    
    uvicorn.run(
        "app.main:app",
        host=settings.API_HOST,
        port=settings.API_PORT,
        reload=settings.API_RELOAD,
        log_level=settings.LOG_LEVEL.lower()
    )