class ConversationEngine:

    def generate_response(
        self,
        session,
        state,
        user_message,
    ):

        stage = session.stage

        if stage == "greeting":

            return {
                "message": (
                    "What brings you to the hospital today?"
                ),
                "next_stage": "reason_for_visit",
            }

        if stage == "reason_for_visit":

            return {
                "message": (
                    "Can you tell me more about what "
                    "you are experiencing?"
                ),
                "next_stage": "symptom_collection",
            }

        if stage == "symptom_collection":

            return {
                "message": (
                    "How long have you been experiencing "
                    "this problem?"
                ),
                "next_stage": "symptom_details",
            }

        if stage == "symptom_details":

            return {
                "message": (
                    "Are you currently taking any "
                    "medications?"
                ),
                "next_stage": "medications",
            }

        if stage == "medications":

            return {
                "message": (
                    "Do you have any known allergies?"
                ),
                "next_stage": "allergies",
            }

        if stage == "allergies":

            return {
                "message": (
                    "Thank you. I have collected the "
                    "initial information."
                ),
                "next_stage": "summary",
            }

        return {
            "message": (
                "Thank you. Let's continue."
            ),
            "next_stage": stage,
        }