import logging
from fastapi import FastAPI, HTTPException
from contextlib import asynccontextmanager
from fastapi.middleware.cors import CORSMiddleware

from api.schemas import ChatRequest, ChatResponse, UploadResponse
from core.rag_pipeline import RagPipeline

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

pipeline_resources = {}

@asynccontextmanager
async def lifespan(app: FastAPI):
    logger.info("Starting CorpGuide AI API...")
    try:
        pipeline_resources["rag"] = RagPipeline()
        logger.info("CorpGuide AI API ready for queries")
    
    except Exception as e:
        logger.error(f"Failed to initialize CorpGuide AI API: {str(e)}")
        raise e

    yield

    pipeline_resources.clear()
    logger.info("API shut down.")

app = FastAPI(
    title="CorpGuide AI",
    description="AI-powered HR policy assistant",
    version="1.0.0",
    lifespan=lifespan
)

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

@app.get("/")
async def read_index():
    return {"status": "online", "message": "CorpGuide AI API is running. Use the Frontend application to interact."}

@app.post("/chat", response_model=ChatResponse)
async def chat(request: ChatRequest):
    try:
        if 'rag' not in pipeline_resources:
            raise HTTPException(status_code=503, detail="System is initializing, try again later")

        rag = pipeline_resources['rag']

        result = rag.process_query(
            question= request.question,
            chat_history=request.chat_history
        )

        return ChatResponse(
            answer=result["answer"],
            sources=result["sources"],
            latency=result["latency"]
        )

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