gistfile1.js

create(params, cb) {
    let sourcePromise = null;
    if (params.provider === 'facebook') {
      let options = {
        sourceId: params.providerId,
        source: params.provider,
        token: params.oauth_token
      };
      
      sourcePromise = this.methods.users.sources.getOne(options);
    } else {
      sourcePromise = SeqPromise.resolve(false);
    }
    
    return sourcePromise
      .then((foundUser) => {
        console.log(foundUser);
        if (foundUser && foundUser.internal) {
          params.foundUser = foundUser;
          params.id = params.foundUser.id;
          params.userId = params.foundUser.id;
          
          return this.methods.users.createRedeem(params);
        } else {
          return this.methods.users.createNew(params);
        }
      }).nodeify(cb);
  }