src/sales_assistant/agent_main/agent_node.py

"""
Basis agent node that creates the initial agent with the system prompt.
Need to use the prompt from the prompts/system_prompt.py file
"""
import os
from typing import Dict, Any
from langchain_core.messages import SystemMessage
from langgraph.graph import MessagesState
from langchain.chat_models import init_chat_model
from dotenv import load_dotenv
from ..prompts.system_prompt import SYSTEM_PROMPT
from .tools_node import get_all_tools

# Load environment variables
load_dotenv()

def agent_node(state: MessagesState) -> Dict[str, Any]:
    """
    Agent node using LangChain's built-in init_chat_model with env configuration.
    
    Args:
        state: MessagesState containing the conversation history
        
    Returns:
        Dict containing the updated messages
    """
    # Get model configuration from environment variables
    model_name = os.getenv("MODEL_NAME", "gpt-5-mini")
    model_provider = os.getenv("MODEL_PROVIDER", "openai")
    
    # Use LangChain's built-in init_chat_model with env config
    model = init_chat_model(
        model=model_name,
        model_provider=model_provider,
        api_key=os.getenv("OPENAI_API_KEY")
    )
    
    # Get tools and bind them using built-in method
    tools = get_all_tools()
    model_with_tools = model.bind_tools(tools)
    
    # Get current messages
    messages = state["messages"]
    
    # Add system prompt if not present using built-in message handling
    if not messages or not isinstance(messages[0], SystemMessage):
        system_message = SystemMessage(content=SYSTEM_PROMPT)
        messages = [system_message] + messages
    
    # Generate response using built-in invoke
    response = model_with_tools.invoke(messages)
    
    return {"messages": [response]}