class NodeCounter

class NodeCounter extends DestinationBase implements ContainerFactoryPluginInterface {
    
    /**
     * The database connection.
     *
     * @var \Drupal\Core\Database\Connection
     */
    protected $connection;
    
    /**
     * Constructs a node counter plugin.
     *
     * @param array $configuration
     *   Plugin configuration.
     * @param string $plugin_id
     *   The plugin ID.
     * @param mixed $plugin_definition
     *   The plugin definition.
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   The current migration.
     * @param \Drupal\Core\Database\Connection $connection
     *   The database connection.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration, Connection $connection) {
        parent::__construct($configuration, $plugin_id, $plugin_definition, $migration);
        $this->connection = $connection;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, MigrationInterface $migration = NULL) {
        return new static($configuration, $plugin_id, $plugin_definition, $migration, $container->get('database'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIds() {
        return [
            'nid' => [
                'type' => 'integer',
            ],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function fields(MigrationInterface $migration = NULL) {
        return [
            'nid' => $this->t('The ID of the node to which these statistics apply.'),
            'totalcount' => $this->t('The total number of times the node has been viewed.'),
            'daycount' => $this->t('The total number of times the node has been viewed today.'),
            'timestamp' => $this->t('The most recent time the node has been viewed.'),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function import(Row $row, array $old_destination_id_values = []) {
        $nid = $row->getDestinationProperty('nid');
        $daycount = $row->getDestinationProperty('daycount');
        $totalcount = $row->getDestinationProperty('totalcount');
        $timestamp = $row->getDestinationProperty('timestamp');
        $this->connection
            ->merge('node_counter')
            ->key('nid', $nid)
            ->fields([
            'daycount' => $daycount,
            'totalcount' => $totalcount,
            'timestamp' => $timestamp,
        ])
            ->expression('daycount', 'daycount + :daycount', [
            ':daycount' => $daycount,
        ])
            ->expression('totalcount', 'totalcount + :totalcount', [
            ':totalcount' => $totalcount,
        ])
            ->expression('timestamp', 'CASE WHEN timestamp > :timestamp1 THEN timestamp ELSE :timestamp2 END', [
            ':timestamp1' => $timestamp,
            ':timestamp2' => $timestamp,
        ])
            ->execute();
        return [
            $row->getDestinationProperty('nid'),
        ];
    }

}