function enabledAccountsFor(hosters, hoster, hasCreds) {
  const list = hosters && hosters[hoster];
  if (!Array.isArray(list)) return [];
  return list.filter(a => a && a.enabled !== false && hasCreds(hoster, a));
}

function createAccountPicker({ hosters, hosterSettings, hasCreds }) {
  const rotIdx = Object.create(null);
  return function pick(hoster) {
    const enabled = enabledAccountsFor(hosters, hoster, hasCreds);
    if (enabled.length === 0) return null;
    const hs = (hosterSettings && hosterSettings[hoster]) || {};
    if (hs.rotateAccounts === true && enabled.length > 1) {
      const i = (rotIdx[hoster] || 0) % enabled.length;
      rotIdx[hoster] = (rotIdx[hoster] || 0) + 1;
      return enabled[i];
    }
    return enabled[0];
  };
}

module.exports = { createAccountPicker, enabledAccountsFor };