/**
 * Twitch provider using Helix API.
 *
 * Fix (2026-09): the App Access Token is now cached process-wide (they last
 * ~60 days) instead of being fetched on every search, and both the token
 * request and the Helix call retry once with a short backoff — the earlier
 * single-shot behaviour made the provider intermittently return [] when the
 * token endpoint or Helix hiccuped (observed on container cold starts).
 * Missing TWITCH_CLIENT_ID/SECRET now fail fast with a clear error instead of
 * calling the OAuth endpoint with undefined credentials.
 */

// Process-wide app access token cache
let cachedToken = null; // { token, clientId, expiresAtMs }

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

async function fetchWithTimeout(url, options = {}, timeoutMs = 10_000) {
  const controller = new AbortController();
  const tid = setTimeout(() => controller.abort(), timeoutMs);
  try {
    return await fetch(url, { ...options, signal: controller.signal });
  } finally {
    clearTimeout(tid);
  }
}

async function getAppAccessToken(force = false) {
  const clientId = process.env.TWITCH_CLIENT_ID;
  const clientSecret = process.env.TWITCH_CLIENT_SECRET;
  if (!clientId || !clientSecret) {
    const err = new Error('twitch_not_configured: TWITCH_CLIENT_ID / TWITCH_CLIENT_SECRET missing');
    err.code = 'NOT_CONFIGURED';
    throw err;
  }
  if (!force && cachedToken && Date.now() < cachedToken.expiresAtMs) {
    return cachedToken;
  }

  let lastErr = null;
  for (let attempt = 0; attempt < 3; attempt++) {
    try {
      const authResponse = await fetchWithTimeout('https://id.twitch.tv/oauth2/token', {
        method: 'POST',
        headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
        body: new URLSearchParams({
          client_id: clientId,
          client_secret: clientSecret,
          grant_type: 'client_credentials',
        }),
      });
      if (!authResponse.ok) {
        // 400/403 = bad credentials: do not retry
        if (authResponse.status === 400 || authResponse.status === 401 || authResponse.status === 403) {
          throw Object.assign(new Error(`twitch_auth_rejected_${authResponse.status}`), { code: 'AUTH_REJECTED' });
        }
        throw new Error(`twitch_auth_error_${authResponse.status}`);
      }
      const { access_token, expires_in } = await authResponse.json();
      if (!access_token) throw new Error('twitch_auth_no_token');
      cachedToken = {
        token: access_token,
        clientId,
        // refresh 24h before actual expiry
        expiresAtMs: Date.now() + Math.max(3600, Number(expires_in || 3600) - 86_400) * 1000,
      };
      return cachedToken;
    } catch (e) {
      lastErr = e;
      if (e && e.code === 'AUTH_REJECTED') throw e;
      if (attempt < 2) await sleep(400 * (attempt + 1));
    }
  }
  throw lastErr || new Error('twitch_auth_failed');
}

async function helixSearchChannels(q, first, after, token, clientId) {
  let lastErr = null;
  for (let attempt = 0; attempt < 3; attempt++) {
    try {
      const params = new URLSearchParams({ query: q, first: String(first) });
      if (after) params.set('after', after);
      const response = await fetchWithTimeout(
        `https://api.twitch.tv/helix/search/channels?${params.toString()}`,
        {
          headers: {
            'Client-ID': clientId,
            'Authorization': `Bearer ${token}`,
          },
        },
      );
      if (response.status === 401) {
        // token expired/revoked server-side: force refresh once, then retry
        const fresh = await getAppAccessToken(true);
        return { data: [], cursor: null, token: fresh.token, retry: true };
      }
      if (!response.ok) throw new Error(`twitch_api_error_${response.status}`);
      const data = await response.json();
      return { data: Array.isArray(data.data) ? data.data : [], cursor: data?.pagination?.cursor || null };
    } catch (e) {
      lastErr = e;
      if (attempt < 2) await sleep(400 * (attempt + 1));
    }
  }
  throw lastErr || new Error('twitch_api_failed');
}

const handler = {
  id: 'tw',
  label: 'Twitch',
  /**
   * @param {string} q
   * @param {{ limit: number, page?: number }} opts
   * @returns {Promise<Array<any>>}
   */
  async search(q, opts) {
    const { limit = 10, page = 1 } = opts || {};
    const query = String(q || '').trim();
    if (!query) return [];

    try {
      const appToken = await getAppAccessToken();
      const perPage = Math.min(Math.max(1, Number(limit || 10)), 100);
      const targetPage = Math.max(1, Number(page || 1));

      let after = '';
      let currentPage = 1;
      let lastData = [];

      while (currentPage <= targetPage) {
        let res = await helixSearchChannels(query, perPage, after, appToken.token, appToken.clientId);
        // One forced retry with a fresh token when Helix rejects the cached one
        if (res.retry) {
          res = await helixSearchChannels(query, perPage, after, res.token, appToken.clientId);
        }
        if (currentPage === targetPage) {
          lastData = res.data;
          break;
        }
        const nextCursor = res.cursor;
        if (!nextCursor) {
          lastData = [];
          break;
        }
        after = String(nextCursor);
        currentPage++;
      }

      // NOTE: helix/search/channels ne retourne QUE des chaînes (jamais des VODs).
      // Les chaînes hors-ligne étaient étiquetées type 'video', ce qui faisait
      // croire au frontend à une VOD jouable via ?video=<id> -> erreur player.
      // On les étiquette 'live' / 'channel' pour forcer l'embed ?channel=<login>.
      return lastData.map((item) => {
        const login = item.broadcaster_login || item.user_login || undefined;
        const thumb = item.thumbnail_url || '';
        return {
          title: item.title || item.display_name,
          id: item.id,
          url: login ? `https://www.twitch.tv/${login}` : undefined,
          thumbnail: thumb ? thumb.replace('{width}x{height}', '440x248') : undefined,
          uploaderName: item.display_name,
          channelId: item.id || undefined,
          channelHandle: login,
          channelExternalId: login,
          uploaderAvatar: thumb ? thumb.replace('{width}x{height}', '70x70') : undefined,
          type: item.is_live ? 'live' : 'channel',
          isLive: Boolean(item.is_live),
        };
      });
    } catch (error) {
      console.error('Twitch search error:', error?.message || error);
      return [];
    }
  },
};

export default handler;