"""
Slide 54: Slide 27
Section 2: LangGraph 1.0
Source: slides/section2-langgraph/section2.pptx

Сгенерировано автоматически из slide-NN.js / sectionN.pptx.
Паттерн провайдера скопирован из
bro-js/agents/teacher/assistant/src/angry_teacher/llm.py.

Запуск:
  cd langchain-evolution-deck
  cp .env.example .env   # заполни OPENAI_API_KEY
  python examples/slide-054/script.py
"""
import os
from dotenv import load_dotenv
from langchain_openai import ChatOpenAI

load_dotenv()

llm = ChatOpenAI(
    # model="openrouter/free",
    # model="qwen/qwen3.5-35b-a3b",
    model="openai/gpt-oss-20b",
    # model="nvidia/nemotron-3-nano",
    # model="qwen/qwen3.5-9b",
    base_url="https://llm.brojs.ru/v1",
    # base_url="https://api.minimax.io/v1",
    # base_url="http://0.0.0.0:8090/v1",
    # base_url="https://openrouter.ai/api/v1",
    # api_key=os.getenv("MINIMAX_API_KEY"),
    api_key=(os.getenv("OPENAI_API_KEY") or "").strip() or None,
    temperature=0.7,
    stream_usage=True,
)


# === Code from slide 54 ===
  from langgraph.graph import StateGraph, START, END
  from langgraph.prebuilt import ToolNode
  # tools, llm, agent, route -- из предыдущего слайда
  g = StateGraph(State)
  g.add_node("agent", agent)
> g.add_node("tools", ToolNode(tools))
  g.add_edge(START, "agent")
  g.add_conditional_edges("agent", route, {"tools": "tools", END: END})
  g.add_edge("tools", "agent")
> app = g.compile()

  # Цикл: agent решает -> tools исполняет -> agent снова читает результат
> result = app.invoke({
>     "messages": [{"role": "user", "content": "What is 2 + 3?"}]
  })
  print(result["messages"][-1].content)