import traceback
from contextlib import asynccontextmanager

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse

from routes.chat import router as chat_router
from routes.upload import router as upload_router
from routes.health import router as health_router

from utils.logger import logger
from llm.model_loader import get_llm
from embeddings.embedding_model import get_embedding_model
from embeddings.vector_store import load_vector_store


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Eagerly load models on startup
    logger.info("Eagerly loading LLM model on startup...")
    try:
        get_llm()
        logger.info("LLM model loaded successfully!")
    except Exception as e:
        logger.error(f"Error loading LLM model on startup: {e}")

    logger.info("Eagerly loading embedding model on startup...")
    try:
        get_embedding_model()
        logger.info("Embedding model loaded successfully!")
    except Exception as e:
        logger.error(f"Error loading embedding model on startup: {e}")

    logger.info("Eagerly loading vector store on startup...")
    try:
        load_vector_store()
        logger.info("Vector store loaded successfully!")
    except Exception as e:
        logger.error(f"Error loading vector store on startup: {e}")

    yield


app = FastAPI(title="AI Assistant", lifespan=lifespan)

app.include_router(chat_router)
app.include_router(upload_router)
app.include_router(health_router)


# Global fallback: convert unhandled exceptions to JSON 500 with detail
@app.exception_handler(Exception)
async def global_exception_handler(request: Request, exc: Exception):
    logger.error(f"Unhandled exception: {exc}\n{traceback.format_exc()}")
    return JSONResponse(
        status_code=500,
        content={
            "error": type(exc).__name__,
            "detail": str(exc),
        }
    )


@app.get("/")
def root():
    return {"message": "AI Engine Running"}