"""
Slide 17: Parallel + Branch -- fan-out и роутинг
Section 1: LangChain 1.0
Source: slides/section1-chains/slide-17.js

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-017/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 17 ===
from langchain_core.runnables import RunnableParallel, RunnableBranch

# Parallel -- один вход, несколько параллельных Runnable-ов, dict на выходе
joke_chain = ChatPromptTemplate.from_template("Tell a joke about {topic}") | model
poem_chain = ChatPromptTemplate.from_template("Write a poem about {topic}") | model

parallel = RunnableParallel(joke=joke_chain, poem=poem_chain)
result = parallel.invoke({"topic": "cats"})
print(result.keys())  # dict_keys(["joke", "poem"])

# Branch -- if/else роутинг по условию
branch = RunnableBranch(
    (lambda x: "code" in x["topic"].lower(), code_chain),
    (lambda x: "math" in x["topic"].lower(), math_chain),
    general_chain,  # default
)
print(branch.invoke({"topic": "code review"}))