agent.py

import os
from dotenv import load_dotenv
from langgraph.graph import START, StateGraph, MessagesState
from langgraph.prebuilt import tools_condition
from langgraph.prebuilt import ToolNode
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_groq import ChatGroq
from langchain_huggingface import ChatHuggingFace, HuggingFaceEndpoint#, HuggingFaceEmbeddings
# from langchain_community.vectorstores import SupabaseVectorStore
from langchain_core.messages import SystemMessage, HumanMessage
# from langchain.tools.retriever import create_retriever_tool
# from supabase.client import Client, create_client

from prompt import SYSTEM_PROMPT
from tools import add, subtract, multiply, divide, web_search

load_dotenv()

HUGGINGFACEHUB_API_TOKEN = os.environ["HF_TOKEN"]

tools = [add, subtract, multiply, divide, web_search]


# Build graph function
def build_graph(provider: str = "huggingface") -> StateGraph:
    """Build the graph"""
    sys_msg = SystemMessage(content=SYSTEM_PROMPT)
    if provider == "google":
        # Google Gemini
        llm = ChatGoogleGenerativeAI(model="gemini-2.0-flash", temperature=0)
    elif provider == "groq":
        # Groq https://console.groq.com/docs/models
        llm = ChatGroq(model="qwen-qwq-32b", temperature=0) # optional : qwen-qwq-32b gemma2-9b-it
    elif provider == "huggingface":
        llm = ChatHuggingFace(
            llm=HuggingFaceEndpoint(
                repo_id="Qwen/Qwen2.5-Coder-32B-Instruct",
                huggingfacehub_api_token=HUGGINGFACEHUB_API_TOKEN
            ),
        )
    else:
        raise ValueError("Invalid provider. Choose 'google', 'groq' or 'huggingface'.")
    llm_with_tools = llm.bind_tools(tools)

    # Node
    def assistant(state: MessagesState):
        """Assistant node"""
        message = [sys_msg] + state["messages"]
        return {"messages": [llm_with_tools.invoke(message)]}

    builder = StateGraph(MessagesState)
    builder.add_node("assistant", assistant)
    builder.add_node("tools", ToolNode(tools))
    builder.add_edge(START, "assistant")
    builder.add_conditional_edges(
        "assistant",
        tools_condition,
    )
    builder.add_edge("tools", "assistant")

    # Compile graph
    return builder.compile()


class BasicAgent:
    """A langgraph agent."""
    def __init__(self):
        print("BasicAgent initialized.")
        self.graph = build_graph()

    def __call__(self, question: str) -> str:
        print(f"Agent received question (first 50 chars): {question[:50]}...")
        # Wrap the question in a HumanMessage from langchain_core
        messages = [HumanMessage(content=question)]
        messages = self.graph.invoke({"messages": messages})
        answer = messages['messages'][-1].content
        return answer[14:]