class User

class User extends DrupalSqlBase {
    
    /**
     * {@inheritdoc}
     */
    public function query() {
        return $this->select('users', 'u')
            ->fields('u', array_keys($this->baseFields()))
            ->condition('u.uid', 0, '>');
    }
    
    /**
     * {@inheritdoc}
     */
    public function fields() {
        $fields = $this->baseFields();
        // Add roles field.
        $fields['roles'] = $this->t('Roles');
        return $fields;
    }
    
    /**
     * {@inheritdoc}
     */
    public function prepareRow(Row $row) {
        // User roles.
        $roles = $this->select('users_roles', 'ur')
            ->fields('ur', [
            'rid',
        ])
            ->condition('ur.uid', $row->getSourceProperty('uid'))
            ->execute()
            ->fetchCol();
        $row->setSourceProperty('roles', $roles);
        // We are adding here the Event contributed module column.
        // @see https://api.drupal.org/api/drupal/modules%21user%21user.install/function/user_update_7002/7
        if ($row->hasSourceProperty('timezone_id') && $row->getSourceProperty('timezone_id')) {
            if ($this->getDatabase()
                ->schema()
                ->tableExists('event_timezones')) {
                $event_timezone = $this->select('event_timezones', 'e')
                    ->fields('e', [
                    'name',
                ])
                    ->condition('e.timezone', $row->getSourceProperty('timezone_id'))
                    ->execute()
                    ->fetchField();
                if ($event_timezone) {
                    $row->setSourceProperty('event_timezone', $event_timezone);
                }
            }
        }
        // Unserialize Data.
        $data = $row->getSourceProperty('data');
        if ($data !== NULL) {
            $row->setSourceProperty('data', unserialize($row->getSourceProperty('data')));
        }
        return parent::prepareRow($row);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIds() {
        return [
            'uid' => [
                'type' => 'integer',
                'alias' => 'u',
            ],
        ];
    }
    
    /**
     * Returns the user base fields to be migrated.
     *
     * @return array
     *   Associative array having field name as key and description as value.
     */
    protected function baseFields() {
        $fields = [
            'uid' => $this->t('User ID'),
            'name' => $this->t('Username'),
            'pass' => $this->t('Password'),
            'mail' => $this->t('Email address'),
            'theme' => $this->t('Theme'),
            'signature' => $this->t('Signature'),
            'signature_format' => $this->t('Signature format'),
            'created' => $this->t('Registered timestamp'),
            'access' => $this->t('Last access timestamp'),
            'login' => $this->t('Last login timestamp'),
            'status' => $this->t('Status'),
            'timezone' => $this->t('Timezone'),
            'language' => $this->t('Language'),
            'picture' => $this->t('Picture'),
            'init' => $this->t('Init'),
            'data' => $this->t('User data'),
        ];
        // The database connection may not exist, for example, when building
        // the Migrate Message form.
        if ($source_database = $this->database) {
            // Possible field added by Date contributed module.
            // @see https://api.drupal.org/api/drupal/modules%21user%21user.install/function/user_update_7002/7
            if ($source_database->schema()
                ->fieldExists('users', 'timezone_name')) {
                $fields['timezone_name'] = $this->t('Timezone (Date)');
            }
            // Possible field added by Event contributed module.
            // @see https://api.drupal.org/api/drupal/modules%21user%21user.install/function/user_update_7002/7
            if ($source_database->schema()
                ->fieldExists('users', 'timezone_id')) {
                $fields['timezone_id'] = $this->t('Timezone (Event)');
            }
        }
        return $fields;
    }

}