// Slide 13: LCEL -- the pipe operator and the Runnable protocol
// Code slide: every component is a Runnable, | composes them.

const ds = require('./design-system');

function createSlide(pres, theme) {
  const slide = pres.addSlide();
  ds.helpers.slideBase(slide, pres, theme);

  ds.helpers.addHeader(slide, pres, theme, {
    eyebrow: 'STAGE 1: CHAINS',
    section: 'LCEL',
    title: '| -- декларативная композиция',
    sectionNumber: 1,
  });

  ds.helpers.addCodeBlock(slide, pres, theme, {
    x: 0.5, y: 1.5, w: 9.0, h: 3.25,
    language: 'python',
    filePath: 'examples/lcel_intro.py',
    code: [
      'from langchain_core.prompts import ChatPromptTemplate',
      'from langchain_core.output_parsers import StrOutputParser',
      'from langchain.chat_models import init_chat_model',
      '',
      'prompt = ChatPromptTemplate.from_messages([',
      '    ("system", "You are a {style} assistant."),',
      '    ("human", "{question}"),',
      '])',
      'model = init_chat_model("openai:gpt-4.1-mini")',
      '',
      '# prompt, model, parser -- все три реализуют Runnable',
      '# Оператор | склеивает их в один chain',
      'chain = prompt | model | StrOutputParser()',
      '',
      '# type(chain) -> RunnableSequence',
      'print(type(chain).__name__)',
      '',
      '# invoke -> dict на вход, str на выход',
      'print(chain.invoke({"style": "concise", "question": "What is LCEL?"}))',
    ].join('\n'),
  });

  ds.helpers.addCallout(slide, pres, theme, {
    x: 0.5, y: 4.85, w: 9.0, h: 0.3,
    kind: 'success',
    text: 'Runnable -- единый контракт: invoke / batch / stream / ainvoke / abatch / astream / async stream.',
  });

  ds.helpers.addSourceLine(slide, pres, theme, {
    source: 'python.langchain.com/docs/concepts/lcel/',
  });
  ds.helpers.addPageNumber(slide, pres, theme, 13);
}

module.exports = { createSlide };