agent.py

from dotenv import load_dotenv 
import os
from typing import TypedDict, Annotated
from langgraph.graph.message import add_messages
from langchain_core.messages import AnyMessage, HumanMessage, SystemMessage
from langgraph.graph import START, StateGraph, MessagesState
from langgraph.prebuilt import tools_condition, ToolNode
from langchain_ollama import ChatOllama
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_groq import ChatGroq
import asyncio

from tools import get_tools

load_dotenv() 

class Agent():
    def __init__(self):
        self.tools = get_tools()

        with open('system_prompt.txt', 'r') as f:
            system_prompt = f.read()
        self.sys_msg = SystemMessage(content=system_prompt)

        print("Agent initialized.")

    def build_graph(self, provider: str = '', model: str = None):
        if provider == 'ollama':
            if not model:
                model = "llama3.1:8b"
            llm = ChatOllama(model=model, temperature=0)
        elif provider == 'google':
            if not model:
                model = "gemini-2.5-flash"
            gemini_api_key = os.getenv("GEMINI_API_KEY")
            llm = ChatGoogleGenerativeAI(model=model, temperature=0,google_api_key=gemini_api_key)
        elif provider == 'groq':
            if not model:
                model = "meta-llama/llama-4-scout-17b-16e-instruct"
                #model = "meta-llama/llama-4-maverick-17b-128e-instruct" 
            groq_api_key = os.getenv("GROQ_API_KEY")
            llm = ChatGroq(model=model, temperature=0, groq_api_key=groq_api_key)
        else:
            raise ValueError(f'Provider {provider} not supported')
        llm_with_tools = llm.bind_tools(self.tools)

        def assistant(state: MessagesState):
            """Assistant node"""
            new_message = llm_with_tools.invoke([self.sys_msg] + state["messages"])
            return {"messages": [new_message]}
        
        builder = StateGraph(MessagesState)
        builder.add_node("assistant", assistant).set_entry_point("assistant")
        builder.add_node("tools", ToolNode(self.tools))
        builder.add_edge(START, "assistant")
        builder.add_conditional_edges(
            "assistant",
            tools_condition,
        )
        builder.add_edge("tools", "assistant")

        # Compile graph
        return builder.compile()

    def __call__(self, question: str, attachment: str | None) -> str:
        print("\n\n#######################################################################\n")
        print("#################### AGENT RECEIVED A NEW QUESTION ####################\n")
        print("#######################################################################\n\n")
        # Wrap the question in a HumanMessage from langchain_core
        if attachment:    
            attachment_prompt = f"\n\nThe path for the file required to answer this question is: {attachment}\n"
        else:
            attachment_prompt = ""
        messages = [HumanMessage(content=question+attachment_prompt)]
        graph = self.build_graph('google')
        messages = graph.invoke({"messages": messages})
        answer = extract_final_answer(messages['messages'][-1].content)
        for m in messages["messages"]:
            m.pretty_print()
        
        return answer
    
def extract_final_answer(response: str) -> str:
    """Extract the final answer from the model response."""
    if "FINAL ANSWER:" in response:
        return response.split("FINAL ANSWER:")[-1].strip()
    else:
        # Fallback: return the full response if no FINAL ANSWER found
        return response.strip()

if __name__ == "__main__":
    def main():    
        agent = Agent()
        question = "Who did the actor who played Ray in the Polish-language version of Everybody Loves Raymond play in Magda M.? Give only the first name."
        model = "gemini-2.5-flash"
        graph = agent.build_graph('google', model)
        messages = [HumanMessage(content=question)]
        messages = graph.invoke({"messages": messages})
        answer = messages['messages'][-1].content
        for m in messages["messages"]:
            m.pretty_print()
    
        print(f"\n\n\nModel response: {extract_final_answer(answer)}")

    main()