"""
Slide 9: MessagesPlaceholder + few-shot
Section 1: LangChain 1.0
Source: slides/section1-chains/slide-09.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-009/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 9 ===
from langchain_core.prompts import (
    ChatPromptTemplate, MessagesPlaceholder, FewShotChatMessagePromptTemplate,
)

# Few-shot блок: примеры "вопрос -> ответ"
examples = [
    {"input": "2+2", "output": "4"},
    {"input": "3*3", "output": "9"},
]
example_prompt = ChatPromptTemplate.from_messages([
    ("human", "{input}"),
    ("ai", "{output}"),
])
few_shot = FewShotChatMessagePromptTemplate(
    example_prompt=example_prompt, examples=examples,
)

# Сборка: system + few-shot + история + текущий вопрос
prompt = ChatPromptTemplate.from_messages([
    ("system", "You are a math assistant."),
    few_shot,
    MessagesPlaceholder("history"),
    ("human", "{question}"),
])