/**
 * OpenAI-совместимый Chat Completions. Общий для импорта и редактора.
 */

/**
 * @returns {null | { provider: string, apiKey: string, baseUrl: string, model: string }}
 */
export function getLlmConfig() {
  if (process.env.DEEPSEEK_API_KEY) {
    return {
      provider: 'deepseek',
      apiKey: process.env.DEEPSEEK_API_KEY,
      baseUrl: (process.env.LLM_BASE_URL || 'https://api.deepseek.com/v1').replace(
        /\/+$/,
        ''
      ),
      model: process.env.LLM_MODEL || 'deepseek-chat',
    };
  }
  if (process.env.OPENAI_API_KEY) {
    return {
      provider: 'openai',
      apiKey: process.env.OPENAI_API_KEY,
      baseUrl: (process.env.LLM_BASE_URL || 'https://api.openai.com/v1').replace(
        /\/+$/,
        ''
      ),
      model: process.env.LLM_MODEL || 'gpt-4o-mini',
    };
  }
  return null;
}

/**
 * @param {{ baseUrl: string, apiKey: string, model: string }} cfg
 * @param {string} system
 * @param {string} user
 * @param {number} [temperature]
 * @returns {Promise<string>} raw assistant message
 */
export async function chatCompletionTextContent(cfg, system, user, temperature = 0.25) {
  const url = `${cfg.baseUrl}/chat/completions`;
  const body = {
    model: cfg.model,
    messages: [
      { role: 'system', content: system },
      { role: 'user', content: user },
    ],
    temperature,
  };
  if (process.env.LLM_NO_JSON !== '1') {
    body.response_format = { type: 'json_object' };
  }
  const ac = new AbortController();
  const t = setTimeout(() => ac.abort(), 120000);
  let res;
  try {
    res = await fetch(url, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Authorization: `Bearer ${cfg.apiKey}`,
      },
      body: JSON.stringify(body),
      signal: ac.signal,
    });
  } catch (e) {
    if (e.name === 'AbortError') {
      const err = new Error('Превышен таймаут ожидания ответа LLM (120 с).');
      err.code = 'llm_timeout';
      throw err;
    }
    const err = new Error(
      e instanceof Error ? e.message : 'Сбой сети при обращении к LLM'
    );
    err.code = 'llm_network';
    throw err;
  } finally {
    clearTimeout(t);
  }
  if (!res.ok) {
    const errText = await res.text();
    const err = new Error(
      `LLM ${res.status}: ${errText.replace(/\s+/g, ' ').slice(0, 280)}`
    );
    err.code = 'llm_http';
    err.status = res.status;
    throw err;
  }
  const data = await res.json();
  const content = data?.choices?.[0]?.message?.content;
  if (typeof content !== 'string' || !content.trim()) {
    const e = new Error('Пустой content в ответе API.');
    e.code = 'llm_empty';
    throw e;
  }
  return content;
}