from fastapi import FastAPI, UploadFile, File, Form, HTTPException
from fastapi.staticfiles import StaticFiles
from fastapi.responses import FileResponse
from fastapi.middleware.cors import CORSMiddleware
from agentLogic.graph import app as rag_app
from processingPdf.indexer import Indexer
import shutil
import os
import logging

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

app = FastAPI()

# Middleware CORS aggiornato
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"], # Più sicuro per il deploy unificato
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Inizializzazione dell'Indexer 
# (Nota: Se vedi che lo Space va in timeout, sposta questa riga dentro upload_pdf)
indexer_worker = Indexer()

# --- GESTIONE FRONTEND STATICO ---
# Assicurati che la cartella 'static' esista (creata dal Dockerfile)
if os.path.exists("static"):
    app.mount("/assets", StaticFiles(directory="static/assets"), name="assets")

@app.get("/")
async def serve_frontend():
    index_path = os.path.join("static", "index.html")
    if os.path.exists(index_path):
        return FileResponse(index_path)
    return {"message": "Backend is running, but static/index.html was not found."}

# --- ENDPOINT API ---

@app.post("/upload")
async def upload_pdf(file: UploadFile = File(...), user_id: str = Form(...)):
    upload_dir = "temp_uploads"
    os.makedirs(upload_dir, exist_ok=True)
    file_path = os.path.join(upload_dir, file.filename)
    
    try:
        logger.info(f"Ricezione file: {file.filename} per l'utente: {user_id}")
        with open(file_path, "wb") as buffer:
            shutil.copyfileobj(file.file, buffer)
        
        indexer_worker.index_pdf(file_path, user_id)
        
        return {
            "status": "success",
            "message": "Indicizzazione completata con successo", 
            "filename": file.filename
        }
    except Exception as e:
        logger.error(f"Errore durante l'upload/indicizzazione: {str(e)}")
        raise HTTPException(status_code=500, detail=str(e))
    finally:
        if os.path.exists(file_path):
            os.remove(file_path)

@app.post("/chat")
async def chat(query: str, filename: str, user_id: str):
    try:
        initial_state = {
            "query": query,
            "user_id": user_id,
            "filename": filename,
            "intent_data": {},
            "context_chunks": [],
            "final_answer": ""
        }
        result = rag_app.invoke(initial_state)
        return {"answer": result["final_answer"]}
    except Exception as e:
        logger.error(f"Errore nella chat endpoint: {str(e)}")
        raise HTTPException(status_code=500, detail="Errore durante l'elaborazione.")

# Gestione rotte React (SPA) per evitare 404 al refresh
@app.exception_handler(404)
async def custom_404_handler(request, __):
    return FileResponse("static/index.html")

# Rimosso il blocco if __name__ == "__main__": 
# perché l'avvio è gestito dal Dockerfile tramite CMD