// --------------------
// Individual providers
// --------------------

async function getHackerNewsSubmissions(url) {
  const endpoint =
    `https://hn.algolia.com/api/v1/search` +
    `?query=${encodeURIComponent(url)}` +
    `&restrictSearchableAttributes=url` +
    `&tags=story`;

  const response = await fetch(endpoint);

  if (!response.ok) {
    throw new Error(`HN search failed: ${response.status}`);
  }

  const data = await response.json();

  return (data.hits || []).map(hit => ({
    id: hit.objectID,
    title: hit.title,
    url: hit.url,
    author: hit.author,
    points: hit.points,
    comments: hit.num_comments,
    createdAt: hit.created_at,
    discussionUrl: `https://news.ycombinator.com/item?id=${hit.objectID}`
  }));
}

async function getLobstersSubmissions(url) {
  try {
    const endpoint =
      `https://lobste.rs/search.json?q=${encodeURIComponent(url)}`;

    const response = await fetch(endpoint);

    if (!response.ok) {
      return [];
    }

    const results = await response.json();

    return (results || [])
      .filter(item => item.url === url)
      .map(item => ({
        id: item.short_id,
        title: item.title,
        url: item.url,
        author: item.submitter_user?.username,
        points: item.score,
        comments: item.comment_count,
        createdAt: item.created_at,
        discussionUrl: `https://lobste.rs/s/${item.short_id}`
      }));
  } catch {
    return [];
  }
}

// --------------------
// Simple concurrency limiter
// --------------------

async function mapLimit(items, limit, mapper) {
  const results = new Array(items.length);
  let nextIndex = 0;

  async function worker() {
    while (true) {
      const index = nextIndex++;

      if (index >= items.length) {
        return;
      }

      results[index] = await mapper(items[index], index);
    }
  }

  const workers = Array.from(
    { length: Math.min(limit, items.length) },
    worker
  );

  await Promise.all(workers);

  return results;
}

// --------------------
// Main batch function
// --------------------

async function checkUrls(urls, concurrency = 5) {
  return mapLimit(urls, concurrency, async url => {
    const [hackerNews, lobsters] = await Promise.allSettled([
      getHackerNewsSubmissions(url),
      getLobstersSubmissions(url)
    ]);

    return {
      url,

      hackerNews:
        hackerNews.status === "fulfilled"
          ? hackerNews.value
          : [],

      lobsters:
        lobsters.status === "fulfilled"
          ? lobsters.value
          : []
    };
  });
}