from typing import Annotated, TypedDict

from langchain_openai import ChatOpenAI
from langgraph.graph import StateGraph, START, END
from langgraph.graph.message import add_messages


class State(TypedDict):
    messages: Annotated[list, add_messages]


model = ChatOpenAI(
    model="deepseek-v4-flash",
    temperature=0,
    base_url="https://api.deepseek.com/v1",
)


def chatbot(state: State):
    response = model.invoke(state["messages"])
    return {"messages": [response]}


builder = StateGraph(State)

builder.add_node("chatbot", chatbot)
builder.add_edge(START, "chatbot")
builder.add_edge("chatbot", END)

graph = builder.compile()

result = graph.invoke({
    "messages": [
        {
            "role": "user",
            "content": "请用一句话解释 LangGraph。",
        }
    ]
})

print(result["messages"][-1].content)