const DEFAULT_EXA_API_URL = 'https://api.exa.ai/search';

const buildSummary = (results) => {
  if (!results || results.length === 0) {
    return '';
  }

  const snippets = results
    .map((result) => result.snippet || result.highlight)
    .filter(Boolean);

  if (snippets.length === 0) {
    return results
      .slice(0, 3)
      .map((result) => result.title)
      .filter(Boolean)
      .join(' · ');
  }

  return snippets.slice(0, 3).join(' ');
};

const searchExerciseResearch = async ({ query, numResults = 5 }) => {
  if (!query || typeof query !== 'string') {
    throw new Error('Query must be a non-empty string');
  }

  const apiKey = process.env.EXA_API_KEY;
  if (!apiKey) {
    throw new Error('EXA_API_KEY is not configured');
  }

  const apiUrl = process.env.EXA_API_URL || DEFAULT_EXA_API_URL;

  const response = await fetch(apiUrl, {
    method: 'POST',
    headers: {
      'content-type': 'application/json',
      'x-api-key': apiKey
    },
    body: JSON.stringify({
      query,
      numResults,
      type: 'neural',
      useAutoprompt: true
    })
  });

  if (!response.ok) {
    const text = await response.text();
    throw new Error(`Exa search failed: ${response.status} ${text}`);
  }

  const data = await response.json();
  const results = (data.results || []).map((result) => ({
    id: result.id,
    title: result.title,
    url: result.url,
    snippet: Array.isArray(result.highlights) && result.highlights.length > 0
      ? result.highlights[0]
      : result.snippet,
    highlight: result.highlight,
    publishedDate: result.publishedDate,
    score: result.score
  }));

  return {
    summary: buildSummary(results),
    results
  };
};

module.exports = {
  searchExerciseResearch
};