class MessageForm

class MessageForm extends FormBase {
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        $form = new static();
        $form->setStringTranslation($container->get('string_translation'));
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'migrate_messages_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $session_filters = $this->getRequest()
            ->getSession()
            ->get('migration_messages_overview_filter', []);
        $form['filters'] = [
            '#type' => 'details',
            '#open' => TRUE,
            '#title' => $this->t('Filter messages'),
            '#weight' => 0,
        ];
        $form['filters']['message'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Message'),
            '#default_value' => $session_filters['message']['value'] ?? '',
        ];
        $form['filters']['severity'] = [
            '#type' => 'select',
            '#title' => $this->t('Severity level'),
            '#default_value' => $session_filters['severity']['value'] ?? [],
            '#options' => [
                MigrationInterface::MESSAGE_ERROR => $this->t('Error'),
                MigrationInterface::MESSAGE_WARNING => $this->t('Warning'),
                MigrationInterface::MESSAGE_NOTICE => $this->t('Notice'),
                MigrationInterface::MESSAGE_INFORMATIONAL => $this->t('Info'),
            ],
            '#multiple' => TRUE,
            '#size' => 4,
        ];
        $form['filters']['actions'] = [
            '#type' => 'actions',
            '#attributes' => [
                'class' => [
                    'container-inline',
                ],
            ],
        ];
        $form['filters']['actions']['submit'] = [
            '#type' => 'submit',
            '#value' => $this->t('Filter'),
        ];
        $form['filters']['actions']['reset'] = [
            '#type' => 'submit',
            '#value' => $this->t('Reset'),
            '#submit' => [
                '::resetForm',
            ],
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $filters['message'] = [
            'title' => $this->t('message'),
            'where' => 'msg.message LIKE ?',
            'type' => 'string',
        ];
        $filters['severity'] = [
            'title' => $this->t('Severity'),
            'where' => 'msg.level = ?',
            'type' => 'array',
        ];
        $session_filters = $this->getRequest()
            ->getSession()
            ->get('migration_messages_overview_filter', []);
        foreach ($filters as $name => $filter) {
            if ($form_state->hasValue($name)) {
                $session_filters[$name] = [
                    'where' => $filter['where'],
                    'value' => $form_state->getValue($name),
                    'type' => $filter['type'],
                ];
            }
        }
        $this->getRequest()
            ->getSession()
            ->set('migration_messages_overview_filter', $session_filters);
    }
    
    /**
     * Resets the filter form.
     *
     * @param array $form
     *   An associative array containing the structure of the form.
     * @param \Drupal\Core\Form\FormStateInterface $form_state
     *   The current state of the form.
     */
    public function resetForm(array $form, FormStateInterface $form_state) : void {
        $this->getRequest()
            ->getSession()
            ->remove('migration_messages_overview_filter');
    }

}