chaining-promises

new-activation.js

/**
 * Obtains a user from its email
 * @param {string} email Email to get the user.
 * @return {Promise} To be resolved with a user or an error code.
 */
function getUser(email) {
  return api.getUser(email)
    .then(function(user) {
      return user || $q.reject(ERROR_CODE.USER_NOT_EXISTS);
    });
    .catch(function() {
      return $q.reject(ERROR_CODE.API_ERROR);
    });
}

/**
 * Enables the user
 * @param {Object} user User to enable.
 * @return {Promise} To be resolved with a user or rejected with an error code.
 */
function enableUser(user) {
  return api.enableUser(user)
    .catch(function() {
      return $q.reject(ERROR_CODE.API_ERROR);
    });
}

/**
 * Obtains a token from a given user.
 * @param {Object} user User to obtain the token
 * @return {Promise} To be resolved with a token or rejected with an error code.
 */
function getUserToken(user) {
  return api.getUserToken(user)
    .then(function() {
      return token || $q.reject(ERROR_CODE.INVALID_TOKEN);
    })
    .catch(function() {
      return ERROR_CODE.API_ERROR;
    });
}

/**
 * Activates a user an obtains a token.
 * @param {string} email Email to activate the user
 * @return {Promise} To be resolved with a token or rejected with an error code.
 */
function activate(email) {
  return !email ?
    $q.reject(ERROR_CODE.NOT_VALID_PARAMS) :
    getUser(email)
      .then(enableUser)
      .then(getUserToken);
}

/**
 * Manages an error showing a log.
 * @param {number} error Error to manage.
 */
function manageError(error) {
  switch(error) {
    case ERROR_CODE.NOT_VALID_PARAMS:
      console.error('Params are not valid');
      break;
    case ERROR_CODE.USER_NOT_EXISTS:
      console.error('User not exists');
      break;
    case ERROR_CODE.INVALID_TOKEN:
      console.error('Token is invalid');
      break;
    case ERROR_CODE.API_ERROR:
      console.error('API has failed');
      break;
  }
}

/**
 * Main function
 */
function main() {
  activate(email)
    .then(function(token) {
      $scope.token = token;
    })
    .catch(manageError);
}