app.py

import os
import gradio as gr

from typing import TypedDict, Annotated
from langgraph.graph.message import add_messages
from langchain_core.messages import AnyMessage, AIMessage, HumanMessage
from langgraph.prebuilt import ToolNode
from langgraph.graph import START, StateGraph
from langgraph.prebuilt import tools_condition
from langchain_huggingface import HuggingFaceEndpoint, ChatHuggingFace

from tools import DuckDuckGoSearchRun, weather_info_tool, hub_stats_tool
from retriever import guest_info_tool

hf_token = os.getenv("HF_TOKEN")

# 初始化网络搜索工具
search_tool = DuckDuckGoSearchRun()

# 生成包含工具的聊天接口
llm = HuggingFaceEndpoint(
    repo_id="Qwen/Qwen2.5-Coder-32B-Instruct",
    huggingfacehub_api_token=hf_token,
)

chat = ChatHuggingFace(llm=llm, verbose=True)
tools = [guest_info_tool, search_tool, weather_info_tool, hub_stats_tool]
chat_with_tools = chat.bind_tools(tools)

# 生成 AgentState 和 Agent 图
class AgentState(TypedDict):
    messages: Annotated[list[AnyMessage], add_messages]

def assistant(state: AgentState):
    return {
        "messages": [chat_with_tools.invoke(state["messages"])],
    }

##  构建流程图
builder = StateGraph(AgentState)

# 定义节点：执行具体工作
builder.add_node("assistant", assistant)
builder.add_node("tools", ToolNode(tools))

# 定义边：控制流程走向
builder.add_edge(START, "assistant")
builder.add_conditional_edges(
    "assistant",
    # 如果最新消息需要工具调用，则路由到 tools 节点
    # 否则直接响应
    tools_condition,
)
builder.add_edge("tools", "assistant")
alfred = builder.compile()

def predict(message, history):
    history_langchain_format = []
    for msg in history:
        if msg['role'] == "user":
            history_langchain_format.append(HumanMessage(content=msg['content']))
        elif msg['role'] == "assistant":
            history_langchain_format.append(AIMessage(content=msg['content']))
    history_langchain_format.append(HumanMessage(content=message))
    gpt_response = alfred.invoke({"messages": history_langchain_format})
    return gpt_response["messages"][-1].content

if __name__ == "__main__":
    demo = gr.ChatInterface(
        predict,
        type="messages"
    )
    
    demo.launch()