"""
LangGraph Reducer函数演示 - 字符串连接Reducer
"""

import operator
from typing import Annotated
from typing_extensions import TypedDict
from langgraph.graph import StateGraph, START, END


# 6. 字符串连接Reducer
class StringConcatState(TypedDict):
    text: Annotated[str, operator.add]


def add_text_1(state: StringConcatState) -> dict:
    return {"text": "Hello "}


def add_text_2(state: StringConcatState) -> dict:
    return {"text": "World!"}


def run_demo():
    print("3.2 字符串连接Reducer演示:")

    builder = StateGraph(StringConcatState)

    builder.add_node("add_text_1", add_text_1)
    builder.add_node("add_text_2", add_text_2)

    builder.add_edge(START, "add_text_1")
    builder.add_edge(START, "add_text_2")  # 并行执行
    builder.add_edge("add_text_1", END)
    builder.add_edge("add_text_2", END)

    graph = builder.compile()

    result = graph.invoke({"text": "Say: "})
    print(f"初始状态: {{'text': 'Say: '}}")
    print(f"执行结果: {result}\n")


if __name__ == "__main__":
    run_demo()