class DateField

class DateField extends FieldPluginBase {
    
    /**
     * {@inheritdoc}
     */
    public function getFieldFormatterMap() {
        return [
            'date_default' => 'datetime_default',
            'format_interval' => 'datetime_time_ago',
            // The date_plain formatter exists in Drupal 7 but not Drupal 6. It is
            // added here because this plugin is declared for Drupal 6 and Drupal 7.
'date_plain' => 'datetime_plain',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFieldWidgetMap() {
        return [
            'date' => 'datetime_default',
            'datetime' => 'datetime_default',
            'datestamp' => 'datetime_timestamp',
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function defineValueProcessPipeline(MigrationInterface $migration, $field_name, $data) {
        $to_format = DateTimeItemInterface::DATETIME_STORAGE_FORMAT;
        if (isset($data['field_definition']['data'])) {
            $field_data = unserialize($data['field_definition']['data']);
            if (isset($field_data['settings']['granularity'])) {
                $granularity = $field_data['settings']['granularity'];
                $collected_date_attributes = is_numeric(array_keys($granularity)[0]) ? $granularity : array_keys(array_filter($granularity));
                if (empty(array_intersect($collected_date_attributes, [
                    'hour',
                    'minute',
                    'second',
                ]))) {
                    $to_format = DateTimeItemInterface::DATE_STORAGE_FORMAT;
                }
            }
        }
        switch ($data['type']) {
            case 'date':
                $from_format = 'Y-m-d\\TH:i:s';
                break;
            case 'datestamp':
                $from_format = 'U';
                $to_format = 'U';
                break;
            case 'datetime':
                $from_format = 'Y-m-d H:i:s';
                break;
            default:
                throw new MigrateException(sprintf('Field %s of type %s is an unknown date field type.', $field_name, var_export($data['type'], TRUE)));
        }
        $process = [
            'value' => [
                'plugin' => 'format_date',
                'from_format' => $from_format,
                'to_format' => $to_format,
                'source' => 'value',
            ],
        ];
        // If the 'todate' setting is specified the field is now a 'daterange' and
        // so set the end value. If the datetime_range module is not enabled on the
        // destination then end_value is ignored and a message is logged in the
        // relevant migrate message table.
        if (!empty($field_data['settings']['todate'])) {
            $process['end_value'] = $process['value'];
            $process['end_value']['source'] = 'value2';
        }
        $process = [
            'plugin' => 'sub_process',
            'source' => $field_name,
            'process' => $process,
        ];
        $migration->mergeProcessOfProperty($field_name, $process);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFieldType(Row $row) {
        $field_type = parent::getFieldType($row);
        // If the 'todate' setting is specified then change the field type to
        // 'daterange' so we can migrate the end date.
        if ($field_type === 'datetime' && !empty($row->get('settings/todate'))) {
            if (\Drupal::service('module_handler')->moduleExists('datetime_range')) {
                return 'daterange';
            }
            else {
                throw new MigrateException(sprintf("Can't migrate field '%s' with 'todate' settings. Enable the datetime_range module. See https://www.drupal.org/docs/8/upgrade/known-issues-when-upgrading-from-drupal-6-or-7-to-drupal-8#datetime", $row->get('field_name')));
            }
        }
        return $field_type;
    }

}