/**
 * OAuth Google / Twitch pour l'import des favoris et abonnements.
 *
 * - Google (YouTube) : scopes `youtube.readonly` (+ profil). Importe les
 *   abonnements (`subscriptions.list?mine=true`) et les favoris
 *   (`videos.list?myRating=like`).
 * - Twitch : scopes `user:read:follows user:read:subscriptions`. Importe les
 *   chaînes suivies (`/helix/users/follows?from_id=`). Twitch n'a pas de
 *   notion de "like" vidéo : seul l'import abonnements est proposé.
 *
 * Les tokens sont stockés en SQLite (instance locale / auto-hébergée).
 * Ne jamais logger access_token / refresh_token / client_secret.
 */

const GOOGLE_AUTH_URL = 'https://accounts.google.com/o/oauth2/v2/auth';
const GOOGLE_TOKEN_URL = 'https://oauth2.googleapis.com/token';
const TWITCH_AUTH_URL = 'https://id.twitch.tv/oauth2/authorize';
const TWITCH_TOKEN_URL = 'https://id.twitch.tv/oauth2/token';

const GOOGLE_SCOPES = [
  'openid',
  'https://www.googleapis.com/auth/userinfo.profile',
  'https://www.googleapis.com/auth/youtube.readonly',
].join(' ');

const TWITCH_SCOPES = ['user:read:follows', 'user:read:subscriptions'].join(' ');

// state -> { userId, provider, createdAt } (mémoire, 10 min).
const pendingStates = new Map();

function randomState() {
  try {
    const { randomBytes } = require('node:crypto');
    return randomBytes(16).toString('hex');
  } catch {}
  return `${Date.now().toString(36)}${Math.random().toString(36).slice(2)}`;
}

export function createOAuthState(userId, provider, purpose = 'link') {
  const state = randomState();
  pendingStates.set(state, {
    userId: userId == null ? null : String(userId),
    provider: String(provider),
    purpose: String(purpose || 'link'),
    createdAt: Date.now(),
  });
  // Purge opportuniste.
  try {
    const now = Date.now();
    for (const [k, v] of pendingStates) {
      if (now - v.createdAt > 10 * 60 * 1000) pendingStates.delete(k);
    }
  } catch {}
  return state;
}

export function consumeOAuthState(state) {
  const entry = pendingStates.get(String(state || ''));
  if (!entry) return null;
  pendingStates.delete(String(state));
  if (Date.now() - entry.createdAt > 10 * 60 * 1000) return null;
  return entry;
}

export function oauthStatus() {
  const googleId = String(process.env.GOOGLE_CLIENT_ID || '').trim();
  const googleSecret = String(process.env.GOOGLE_CLIENT_SECRET || '').trim();
  const twitchId = String(process.env.TWITCH_CLIENT_ID || '').trim();
  const twitchSecret = String(process.env.TWITCH_CLIENT_SECRET || '').trim();
  return {
    google: {
      configured: Boolean(googleId && googleSecret),
      missing: [...(!googleId ? ['GOOGLE_CLIENT_ID'] : []), ...(!googleSecret ? ['GOOGLE_CLIENT_SECRET'] : [])],
    },
    twitch: {
      configured: Boolean(twitchId && twitchSecret),
      missing: [...(!twitchId ? ['TWITCH_CLIENT_ID'] : []), ...(!twitchSecret ? ['TWITCH_CLIENT_SECRET'] : [])],
    },
  };
}

/** Base publique de l'app (pour la redirect_uri). Priorité au .env explicite. */
export function appBaseUrl(req) {
  const explicit = String(process.env.OAUTH_APP_BASE_URL || '').trim().replace(/\/+$/, '');
  if (explicit) return explicit;
  try {
    const proto = String(req?.headers?.['x-forwarded-proto'] || req?.protocol || 'http').split(',')[0].trim() || 'http';
    const host = String(req?.headers?.['x-forwarded-host'] || req?.headers?.host || req?.get?.('host') || '').trim();
    if (host) return `${proto}://${host}`;
  } catch {}
  return 'http://localhost:4200';
}

export function redirectUriFor(provider, req) {
  const p = String(provider);
  if (p === 'google') {
    const explicit = String(process.env.GOOGLE_REDIRECT_URI || '').trim();
    if (explicit) return explicit;
  }
  if (p === 'twitch') {
    const explicit = String(process.env.TWITCH_REDIRECT_URI || '').trim();
    if (explicit) return explicit;
  }
  return `${appBaseUrl(req).replace(/\/+$/, '')}/api/oauth/${p}/callback`;
}

export function buildAuthUrl(provider, state, req) {
  const p = String(provider);
  if (p === 'google') {
    const clientId = String(process.env.GOOGLE_CLIENT_ID || '').trim();
    if (!clientId) throw Object.assign(new Error('google_oauth_not_configured'), { status: 503 });
    const qs = new URLSearchParams({
      client_id: clientId,
      redirect_uri: redirectUriFor('google', req),
      response_type: 'code',
      scope: GOOGLE_SCOPES,
      access_type: 'offline',
      prompt: 'consent',
      state,
    });
    return `${GOOGLE_AUTH_URL}?${qs.toString()}`;
  }
  if (p === 'twitch') {
    const clientId = String(process.env.TWITCH_CLIENT_ID || '').trim();
    if (!clientId) throw Object.assign(new Error('twitch_oauth_not_configured'), { status: 503 });
    const qs = new URLSearchParams({
      client_id: clientId,
      redirect_uri: redirectUriFor('twitch', req),
      response_type: 'code',
      scope: TWITCH_SCOPES,
      state,
    });
    return `${TWITCH_AUTH_URL}?${qs.toString()}`;
  }
  throw Object.assign(new Error('invalid_oauth_provider'), { status: 400 });
}

async function postForm(url, params) {
  const body = new URLSearchParams(params);
  const resp = await fetch(url, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: body.toString(),
  });
  const data = await resp.json().catch(() => ({}));
  if (!resp.ok) {
    const err = new Error(`oauth_token_failed_${resp.status}`);
    err.status = 502;
    err.details = data;
    throw err;
  }
  return data;
}

export async function exchangeCode(provider, code, req) {
  const p = String(provider);
  if (p === 'google') {
    const data = await postForm(GOOGLE_TOKEN_URL, {
      code: String(code),
      client_id: String(process.env.GOOGLE_CLIENT_ID || ''),
      client_secret: String(process.env.GOOGLE_CLIENT_SECRET || ''),
      redirect_uri: redirectUriFor('google', req),
      grant_type: 'authorization_code',
    });
    return {
      accessToken: data.access_token,
      refreshToken: data.refresh_token || null,
      expiresAt: data.expires_in ? Date.now() + Number(data.expires_in) * 1000 : null,
      scopes: data.scope || GOOGLE_SCOPES,
    };
  }
  if (p === 'twitch') {
    const data = await postForm(TWITCH_TOKEN_URL, {
      code: String(code),
      client_id: String(process.env.TWITCH_CLIENT_ID || ''),
      client_secret: String(process.env.TWITCH_CLIENT_SECRET || ''),
      redirect_uri: redirectUriFor('twitch', req),
      grant_type: 'authorization_code',
    });
    return {
      accessToken: data.access_token,
      refreshToken: data.refresh_token || null,
      expiresAt: data.expires_in ? Date.now() + Number(data.expires_in) * 1000 : null,
      scopes: Array.isArray(data.scope) ? data.scope.join(' ') : TWITCH_SCOPES,
    };
  }
  throw Object.assign(new Error('invalid_oauth_provider'), { status: 400 });
}

export async function refreshAccessToken(provider, refreshToken) {
  const p = String(provider);
  if (p === 'google') {
    const data = await postForm(GOOGLE_TOKEN_URL, {
      refresh_token: String(refreshToken),
      client_id: String(process.env.GOOGLE_CLIENT_ID || ''),
      client_secret: String(process.env.GOOGLE_CLIENT_SECRET || ''),
      grant_type: 'refresh_token',
    });
    return {
      accessToken: data.access_token,
      refreshToken: data.refresh_token || refreshToken,
      expiresAt: data.expires_in ? Date.now() + Number(data.expires_in) * 1000 : null,
    };
  }
  if (p === 'twitch') {
    const data = await postForm(TWITCH_TOKEN_URL, {
      refresh_token: String(refreshToken),
      client_id: String(process.env.TWITCH_CLIENT_ID || ''),
      client_secret: String(process.env.TWITCH_CLIENT_SECRET || ''),
      grant_type: 'refresh_token',
    });
    return {
      accessToken: data.access_token,
      refreshToken: data.refresh_token || refreshToken,
      expiresAt: data.expires_in ? Date.now() + Number(data.expires_in) * 1000 : null,
    };
  }
  throw Object.assign(new Error('invalid_oauth_provider'), { status: 400 });
}

async function getJson(url, accessToken, extraHeaders = {}) {
  const resp = await fetch(url, {
    headers: { Authorization: `Bearer ${accessToken}`, ...extraHeaders },
  });
  const data = await resp.json().catch(() => ({}));
  if (!resp.ok) {
    const err = new Error(`oauth_api_failed_${resp.status}`);
    err.status = resp.status === 401 ? 401 : 502;
    err.details = data;
    throw err;
  }
  return data;
}

// -------------------- Google (YouTube) --------------------

export async function fetchGoogleProfile(accessToken) {
  const data = await getJson('https://www.googleapis.com/oauth2/v2/userinfo', accessToken);
  return {
    id: String(data.id || ''),
    email: String(data.email || ''),
    verifiedEmail: data.verified_email !== false,
    displayName: String(data.name || data.email || 'Google'),
    avatarUrl: String(data.picture || ''),
  };
}

export async function fetchGoogleSubscriptions(accessToken, max = 50) {
  const out = [];
  let pageToken = '';
  while (out.length < max) {
    const qs = new URLSearchParams({
      part: 'snippet',
      mine: 'true',
      maxResults: String(Math.min(50, max - out.length)),
      order: 'alphabetical',
    });
    if (pageToken) qs.set('pageToken', pageToken);
    const data = await getJson(`https://www.googleapis.com/youtube/v3/subscriptions?${qs.toString()}`, accessToken);
    for (const item of Array.isArray(data?.items) ? data.items : []) {
      const sn = item?.snippet || {};
      const channelId = sn?.resourceId?.channelId || '';
      if (!channelId) continue;
      out.push({
        provider: 'youtube',
        externalId: channelId,
        title: sn?.title || channelId,
        handle: null,
        avatarUrl: sn?.thumbnails?.default?.url || sn?.thumbnails?.medium?.url || null,
        url: `https://www.youtube.com/channel/${channelId}`,
      });
    }
    pageToken = data?.nextPageToken || '';
    if (!pageToken) break;
  }
  return out;
}

export async function fetchGoogleLiked(accessToken, max = 25) {
  const qs = new URLSearchParams({
    part: 'snippet,contentDetails',
    myRating: 'like',
    maxResults: String(Math.min(50, max)),
  });
  const data = await getJson(`https://www.googleapis.com/youtube/v3/videos?${qs.toString()}`, accessToken);
  const out = [];
  for (const item of Array.isArray(data?.items) ? data.items : []) {
    const id = item?.id || '';
    const sn = item?.snippet || {};
    if (!id) continue;
    out.push({
      provider: 'youtube',
      videoId: String(id),
      title: sn?.title || '',
      thumbnail: sn?.thumbnails?.medium?.url || sn?.thumbnails?.default?.url || '',
    });
  }
  return out;
}

// -------------------- Twitch --------------------

function twitchClientId() {
  return String(process.env.TWITCH_CLIENT_ID || '').trim();
}

export async function fetchTwitchProfile(accessToken) {
  const data = await getJson('https://api.twitch.tv/helix/users', accessToken, { 'Client-Id': twitchClientId() });
  const u = Array.isArray(data?.data) ? data.data[0] : null;
  if (!u) throw Object.assign(new Error('twitch_profile_failed'), { status: 502 });
  return {
    id: String(u.id || ''),
    displayName: String(u.display_name || u.login || 'Twitch'),
    avatarUrl: String(u.profile_image_url || ''),
    login: String(u.login || ''),
  };
}

export async function fetchTwitchFollows(accessToken, twitchUserId, max = 100) {
  const out = [];
  let cursor = '';
  while (out.length < max) {
    const qs = new URLSearchParams({
      from_id: String(twitchUserId),
      first: String(Math.min(100, max - out.length)),
    });
    if (cursor) qs.set('after', cursor);
    const data = await getJson(`https://api.twitch.tv/helix/users/follows?${qs.toString()}`, accessToken, {
      'Client-Id': twitchClientId(),
    });
    const list = Array.isArray(data?.data) ? data.data : [];
    // Enrichit les logins via /helix/users?id= (display_name + avatar).
    const ids = list.map((f) => f?.to_id).filter(Boolean).slice(0, 100);
    let usersById = new Map();
    if (ids.length) {
      try {
        const uqs = new URLSearchParams();
        ids.forEach((id) => uqs.append('id', String(id)));
        const udata = await getJson(`https://api.twitch.tv/helix/users?${uqs.toString()}`, accessToken, {
          'Client-Id': twitchClientId(),
        });
        for (const u of Array.isArray(udata?.data) ? udata.data : []) {
          usersById.set(String(u.id), u);
        }
      } catch {}
    }
    for (const f of list) {
      const toId = String(f?.to_id || '');
      if (!toId) continue;
      const u = usersById.get(toId);
      const login = String(u?.login || f?.to_name || '');
      out.push({
        provider: 'twitch',
        externalId: login || toId,
        twitchUserId: toId,
        title: String(u?.display_name || f?.to_name || login || toId),
        handle: login || null,
        avatarUrl: String(u?.profile_image_url || ''),
        url: login ? `https://www.twitch.tv/${login}` : '',
      });
    }
    cursor = data?.pagination?.cursor || '';
    if (!cursor || !list.length) break;
  }
  return out;
}