"""
Slide 53: Slide 26
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-053/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 53 ===
  from langchain_openai import ChatOpenAI
  from langchain.tools import tool
  from langgraph.graph.message import add_messages
  from typing import Annotated
  from typing_extensions import TypedDict
  @tool
  def add(a: int, b: int) -> int:
      "Add two numbers."
      return a + b
  tools = [add]
> llm = ChatOpenAI(model="gpt-4o-mini").bind_tools(tools)
  class State(TypedDict):
      messages: Annotated[list, add_messages]
  def agent(state: State):
      return {"messages": [llm.invoke(state["messages"])]}
  def route(state: State) -> str:
>     last = state["messages"][-1]
      return "tools" if getattr(last, "tool_calls", None) else END