class FormOperations

class FormOperations {
    public function __construct(WorkspaceManagerInterface $workspaceManager) {
    }
    
    /**
     * Implements hook_form_alter().
     */
    public function formAlter(array &$form, FormStateInterface $form_state, $form_id) : void {
        // No alterations are needed if we're not in a workspace context.
        if (!$this->workspaceManager
            ->hasActiveWorkspace()) {
            return;
        }
        // Add a validation step for every form if we are in a workspace.
        $this->addWorkspaceValidation($form);
        // If a form has already been marked as safe or not to submit in a
        // workspace, we don't have anything else to do.
        if ($form_state->has('workspace_safe')) {
            return;
        }
        $form_object = $form_state->getFormObject();
        $workspace_safe = $form_object instanceof WorkspaceSafeFormInterface || $form_object instanceof WorkspaceDynamicSafeFormInterface && $form_object->isWorkspaceSafeForm($form, $form_state);
        $form_state->set('workspace_safe', $workspace_safe);
    }
    
    /**
     * Adds our validation handler recursively on each element of a form.
     *
     * @param array &$element
     *   An associative array containing the structure of the form.
     */
    protected function addWorkspaceValidation(array &$element) : void {
        // Recurse through all children and add our validation handler if needed.
        foreach (Element::children($element) as $key) {
            if (isset($element[$key]) && $element[$key]) {
                $this->addWorkspaceValidation($element[$key]);
            }
        }
        if (isset($element['#validate'])) {
            $element['#validate'][] = [
                static::class,
                'validateDefaultWorkspace',
            ];
        }
    }
    
    /**
     * Validation handler which sets a validation error for all unsupported forms.
     */
    public static function validateDefaultWorkspace(array &$form, FormStateInterface $form_state) : void {
        if ($form_state->get('workspace_safe') !== TRUE) {
            $form_state->setError($form, new TranslatableMarkup('This form can only be submitted in the default workspace.'));
        }
    }

}