my_agent.py

import os

from langgraph.prebuilt import ToolNode, tools_condition
from langgraph.graph import StateGraph, START, MessagesState, END
from langchain.agents import create_agent
from langchain_huggingface import HuggingFaceEndpoint, ChatHuggingFace
from langchain_community.tools import DuckDuckGoSearchRun
from langchain_ollama import ChatOllama
from langchain.agents.middleware.types import AgentState
from langchain.messages import HumanMessage, AIMessage, SystemMessage


from prompts import system_prompt, qa_system_prompt
from my_tools import wiki_search, arxiv_search, web_search, visit_webpage, translate_to_english

hf_token = os.getenv("HF_TOKEN")

class GraphMessagesState(MessagesState):
    question: str


# --- Basic Agent Definition ---
# ----- THIS IS WERE YOU CAN BUILD WHAT YOU WANT ------
class BasicAgent:
    def __init__(self):
        model = HuggingFaceEndpoint(
            repo_id="Qwen/Qwen3-8B",
            task="text-generation",
            max_new_tokens=512,
            do_sample=False,
            repetition_penalty=1.03,
        )
        llm = ChatHuggingFace(llm=model, verbose=True)
        
        model = HuggingFaceEndpoint(
            repo_id="TinyLlama/TinyLlama-1.1B-Chat-v1.0",
            task="text-generation",
            max_new_tokens=512,
            do_sample=False,
            repetition_penalty=1.03,
        )
        self.llm_qa = ChatHuggingFace(llm=model, verbose=True)
        # llm = ChatOllama(
        #     model="qwen3:0.6b",
        #     api_base="http://localhost:11434",  # replace with
        #     # debug=True,
        # )
        tools = [
            wiki_search,
            arxiv_search,
            web_search,
            visit_webpage,
            translate_to_english,
        ]

        builder = StateGraph(GraphMessagesState)

        model = create_agent(
            llm,
            tools,
            system_prompt=system_prompt,
        )
        builder.add_node("assistant", model)
        builder.add_node("assistant_qa", self.call_qa)
        builder.add_node("tools", ToolNode(tools))

        # Define edges: these determine how the control flow moves
        builder.add_edge(START, "assistant")
        builder.add_conditional_edges(
            "assistant",
            # If the latest message requires a tool, route to tools
            # Otherwise, provide a direct response
            tools_condition,
            {
                "tools": "tools",
                END: "assistant_qa",
            },
        )
        builder.add_edge("tools", "assistant")
        builder.add_conditional_edges(
            "assistant_qa",
            tools_condition,
            {
                "tools": "tools",
                END: END,
            },
        )
        self.agent = builder.compile()

        print("BasicAgent initialized.")

    def __call__(self, question: str) -> str:
        print(f"Agent received question (first 50 chars): {question[:50]}...")

        fixed_answer = self.generate_answer(question)

        print(f"Agent returning fixed answer: {fixed_answer}")
        return fixed_answer

    def call_qa(self, graph_state: GraphMessagesState) -> str:
        # print(f"Calling LLM QA for question: {graph_state['question']}")
        # print(type(graph_state["messages"]))
        # print(graph_state["messages"])

        # parsed_messages = [
        #     {"role": m.type, "content": m.content} for m in graph_state["messages"]
        # ]
        parsed_messages = [
            SystemMessage(content=qa_system_prompt)
        ]
        parsed_messages.extend(graph_state["messages"][1:])
        parsed_messages.append(HumanMessage(content=f"Question: {graph_state['question']}"))
        print(f"\n\n\n parsed_messages => {parsed_messages}")

        # response = self.llm_qa.invoke(
        #     {
        #         "messages": [
        #             *parsed_messages,
        #             {
        #                 "role": "human",
        #                 "content": graph_state["question"],
        #             },
        #         ]
        #     },
        #     {"callbacks": [langfuse_handler]},
        # )
        response = self.llm_qa.invoke(
            parsed_messages,
            # {"callbacks": [langfuse_handler]},
        )
        print(f"LLAMA 2 -> QA Agent raw response: {response}")
        return response.model_dump()

    def generate_answer(self, question: str) -> str:
        response = self.agent.invoke(
            {
                "messages": [
                    {
                        "role": "system",
                        "content": system_prompt,
                    },
                    {
                        "role": "human",
                        "content": question,
                    },
                ],
                "question": question,
            },
            # {"callbacks": [langfuse_handler]},
        )
        print(f"Agent raw response: {response}")
        return response["messages"][-1].content