merge_accounts_to_auth0_account.js

function (user, context, callback) {
  
  var userApiUrl = auth0.baseUrl + '/users';
  
  function isSocial() {
    return user.identities[0].isSocial;
  }
  
  function deleteSocialUser(user) {
    if (isSocial()){
      request({
      url: userApiUrl + '/' + user.user_id,
      method: 'DELETE',
      headers: {
        Authorization: 'Bearer ' + configuration.AUTH0_API_TOKEN
        }
      }, function (err, response, body){
        if (err) {
          return callback(new UnauthorizedError('Account does not exist.'));
        } 
        return callback(null, user, context);
      });
    } else {
      callback(null, user, context);
    }
  }
    
  var request = require('request@2.56.0');
  // Check if email is verified, we shouldn't automatically
  // merge accounts if this is not the case.
  if (!user.email_verified) {
    return callback(null, user, context);
  }
  var newUserAryTmp = user.user_id.split('|');
  var newUserProvider = newUserAryTmp[0];
  var newUserUserId = newUserAryTmp[1];
  
  request({
   url: userApiUrl,
   headers: {
     Authorization: 'Bearer ' + auth0.accessToken
   },
   qs: {
     search_engine: 'v2',
     q: 'email:"' + user.email + '" -user_id:"' + user.user_id + '"',
   }
  },
  function(err, response, body) {
    if (err) return callback(err);
    if (response.statusCode !== 200) return callback(new Error(body));
    var foundAuth0User = false;
    var data = JSON.parse(body);
    if (data.length > 0) {
      async.each(data, function(targetUser, cb) {
        if (targetUser.email_verified) {
          var aryTmp = targetUser.user_id.split('|');
          var provider = aryTmp[0];
          if (provider === "auth0") {
            foundAuth0User = true;
            request.post({
              url: userApiUrl + '/' + targetUser.user_id + '/identities',
              headers: {
                Authorization: 'Bearer ' + auth0.accessToken
              },
              json: { provider: newUserProvider, user_id: newUserUserId }
            }, function(err, response, body) {
                if (response.statusCode >= 400) {
                 return cb(new Error('Error linking account: ' + response.statusMessage));  
                }
              cb(err);
            });
          }
        } else {
          cb();
        }
      }, function(err) {
        if(!foundAuth0User){
          deleteSocialUser(user);
        } else {        
          callback(null, user, context);
        }
      });
    } else {
      if(!foundAuth0User){
        deleteSocialUser(user);
      } else {        
        callback(null, user, context);
      }
    }
  });
}