from fastapi import APIRouter, HTTPException
from pydantic import BaseModel
from typing import Optional

from src.services.rag_service import rag_service

router = APIRouter()

class ChatRequest(BaseModel):
    question: str
    highlighted_text: Optional[str] = None

class ChatResponse(BaseModel):
    answer: str

@router.post("/chat", response_model=ChatResponse, tags=["Chat"])
async def chat_endpoint(request: ChatRequest):
    """
    Handles user questions by passing them to the RAG service to generate an answer.
    """
    try:
        answer = rag_service.get_answer(
            question=request.question,
            highlighted_text=request.highlighted_text
        )
        return ChatResponse(answer=answer)
    except Exception as e:
        # The service layer should handle its own errors, but we have a fallback.
        print(f"An unexpected error occurred in the chat endpoint: {e}")
        raise HTTPException(status_code=500, detail="An internal error occurred.")