/* innertube.js — YouTube search via the InnerTube JSON API (no yt-dlp spawn).
 * parseSearch() is pure (tested against fixtures/innertube-search.json);
 * search() does the HTTP call. Callers MUST fall back to yt-dlp on any throw. */
const CLIENT = { clientName: 'WEB', clientVersion: '2.20250101.00.00', hl: 'en', gl: 'US' };

export function lengthToSeconds(s) {
  if (typeof s !== 'string' || !/^\d+(:\d{1,2}){0,2}$/.test(s.trim())) return 0;
  return s.trim().split(':').map(Number).reduce((acc, n) => acc * 60 + n, 0);
}

// Cards from a list of itemSectionRenderer-style sections.
function cardsFromSections(sections) {
  const out = [];
  for (const s of sections) {
    for (const it of s?.itemSectionRenderer?.contents || []) {
      const v = it && it.videoRenderer;
      if (!v || typeof v.videoId !== 'string') continue;
      const owner = v.ownerText?.runs?.[0] || {};
      const be = owner.navigationEndpoint?.browseEndpoint || {};
      const path = be.canonicalBaseUrl || (be.browseId ? `/channel/${be.browseId}` : '');
      out.push({
        id: v.videoId,
        title: v.title?.runs?.map((r) => r.text).join('') || '(untitled)',
        channel: owner.text || '',
        channelId: be.browseId || '',
        channelUrl: path ? `https://www.youtube.com${path}` : '',
        duration: lengthToSeconds(v.lengthText?.simpleText),
        thumbnail: `https://i.ytimg.com/vi/${v.videoId}/mqdefault.jpg`,
      });
    }
  }
  return out;
}

const tokenOf = (sections) => {
  for (const s of sections || []) {
    const t = s?.continuationItemRenderer?.continuationEndpoint?.continuationCommand?.token;
    if (t) return t;
  }
  return '';
};

export function parseSearch(json) {
  const sections = json?.contents?.twoColumnSearchResultsRenderer?.primaryContents
    ?.sectionListRenderer?.contents;
  if (!Array.isArray(sections)) throw new Error('innertube: unexpected response shape');
  return cardsFromSections(sections);
}

// First page plus the token for the next one ('' when there is none).
export function parseSearchPage(json) {
  const sections = json?.contents?.twoColumnSearchResultsRenderer?.primaryContents
    ?.sectionListRenderer?.contents;
  if (!Array.isArray(sections)) throw new Error('innertube: unexpected response shape');
  return { cards: cardsFromSections(sections), next: tokenOf(sections) };
}

// A continuation response: more cards plus the next token.
export function parseContinuation(json) {
  const items = (json?.onResponseReceivedCommands || [])
    .flatMap((c) => c?.appendContinuationItemsAction?.continuationItems || []);
  if (!Array.isArray(items) || !items.length) return { cards: [], next: '' };
  return { cards: cardsFromSections(items), next: tokenOf(items) };
}

export async function search(q, { fetchImpl = fetch, timeoutMs = 6000 } = {}) {
  const res = await fetchImpl('https://www.youtube.com/youtubei/v1/search?prettyPrint=false', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ context: { client: CLIENT }, query: q }),
    signal: AbortSignal.timeout(timeoutMs),
  });
  if (!res.ok) throw new Error(`innertube: HTTP ${res.status}`);
  return parseSearch(await res.json());
}

// Up to `limit` results (default 200) by following continuation tokens. The pages
// are a chain, so they are fetched one after another; every page is optional —
// a failure part-way returns what was gathered. `onPage(cards)` lets a caller
// save progress.
export async function searchDeep(q, { limit = 200, fetchImpl = fetch, timeoutMs = 6000, maxPages = 14, onPage } = {}) {
  const post = async (body) => {
    const res = await fetchImpl('https://www.youtube.com/youtubei/v1/search?prettyPrint=false', {
      method: 'POST', headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ context: { client: CLIENT }, ...body }), signal: AbortSignal.timeout(timeoutMs),
    });
    if (!res.ok) throw new Error(`innertube: HTTP ${res.status}`);
    return res.json();
  };
  const first = parseSearchPage(await post({ query: q }));
  const seen = new Set();
  const all = [];
  const add = (cards) => { for (const c of cards) if (!seen.has(c.id)) { seen.add(c.id); all.push(c); } };
  add(first.cards);
  if (onPage) onPage(all.slice());
  let next = first.next;
  for (let i = 0; i < maxPages && next && all.length < limit; i++) {
    let page;
    try { page = parseContinuation(await post({ continuation: next })); } catch { break; }
    if (!page.cards.length) break;
    add(page.cards);
    if (onPage) onPage(all.slice());
    next = page.next;
  }
  return all.slice(0, limit);
}

// Watch-next recommendations use compact renderers or the newer lockup model.
// Traverse only the recommendation contents, never player configuration/ads.
export function parseRelated(json) {
  const contents = json?.contents?.twoColumnWatchNextResults?.secondaryResults?.secondaryResults?.results
    || json?.contents?.singleColumnWatchNextResults?.results?.results?.contents;
  if (!Array.isArray(contents)) throw new Error('innertube: unexpected related response shape');
  const cards = [], seen = new Set();
  function visit(value) {
    if (!value || typeof value !== 'object') return;
    const renderer = value.compactVideoRenderer || value.videoRenderer;
    const model = value.lockupViewModel;
    const id = renderer?.videoId || (model?.contentType === 'LOCKUP_CONTENT_TYPE_VIDEO' ? model.contentId : '');
    if (typeof id === 'string' && /^[\w-]{11}$/.test(id) && !seen.has(id)) {
      const meta = model?.metadata?.lockupMetadataViewModel;
      const part = meta?.metadata?.contentMetadataViewModel?.metadataRows?.[0]?.metadataParts?.[0]?.text;
      const owner = renderer?.shortBylineText?.runs?.[0] || renderer?.longBylineText?.runs?.[0] || {};
      const browse = owner.navigationEndpoint?.browseEndpoint || part?.commandRuns?.[0]?.onTap?.innertubeCommand?.browseEndpoint || {};
      const badge = model?.contentImage?.thumbnailViewModel?.overlays?.flatMap(o => o.thumbnailOverlayBadgeViewModel?.thumbnailBadges || []).find(b => b.thumbnailBadgeViewModel?.text)?.thumbnailBadgeViewModel?.text;
      const title = renderer?.title?.simpleText || renderer?.title?.runs?.map(r => r.text).join('') || meta?.title?.content;
      if (title) { seen.add(id); cards.push({ id, title, channel: owner.text || part?.content || '', channelId: browse.browseId || '', channelUrl: browse.canonicalBaseUrl ? `https://www.youtube.com${browse.canonicalBaseUrl}` : '', duration: lengthToSeconds(renderer?.lengthText?.simpleText || badge), thumbnail: `https://i.ytimg.com/vi/${id}/mqdefault.jpg` }); }
      return;
    }
    // Ignore advertised placements rather than recursing into their videos.
    for (const [key, child] of Object.entries(value)) if (!/adSlot|promoted|adPlacement/i.test(key)) {
      if (Array.isArray(child)) child.forEach(visit); else visit(child);
    }
  }
  contents.forEach(visit);
  return cards;
}
export async function related(videoId, { fetchImpl = fetch, timeoutMs = 4000 } = {}) {
  const response = await fetchImpl('https://www.youtube.com/youtubei/v1/next?prettyPrint=false', {
    method: 'POST', headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ context: { client: CLIENT }, videoId }), signal: AbortSignal.timeout(timeoutMs),
  });
  if (!response.ok) throw new Error(`innertube related: HTTP ${response.status}`);
  return parseRelated(await response.json());
}