class Number

class Number extends FormElementBase {

  /**
   * {@inheritdoc}
   */
  public function getInfo() {
    $class = static::class;
    return [
      '#input' => TRUE,
      '#step' => 1,
      '#process' => [
        [
          $class,
          'processAjaxForm',
        ],
      ],
      '#element_validate' => [
        [
          $class,
          'validateNumber',
        ],
      ],
      '#pre_render' => [
        [
          $class,
          'preRenderNumber',
        ],
      ],
      '#theme' => 'input__number',
      '#theme_wrappers' => [
        'form_element',
      ],
    ];
  }

  /**
   * Form element validation handler for #type 'number'.
   *
   * Note that #required is validated by _form_validate() already.
   */
  public static function validateNumber(&$element, FormStateInterface $form_state, &$complete_form) {
    $value = $element['#value'];
    if ($value === '') {
      return;
    }
    $name = empty($element['#title']) ? $element['#parents'][0] : $element['#title'];

    // Ensure the input is numeric.
    if (!is_numeric($value)) {
      $form_state
        ->setError($element, t('%name must be a number.', [
        '%name' => $name,
      ]));
      return;
    }

    // Ensure that the input is greater than the #min property, if set.
    if (isset($element['#min']) && $value < $element['#min']) {
      $form_state
        ->setError($element, t('%name must be higher than or equal to %min.', [
        '%name' => $name,
        '%min' => $element['#min'],
      ]));
    }

    // Ensure that the input is less than the #max property, if set.
    if (isset($element['#max']) && $value > $element['#max']) {
      $form_state
        ->setError($element, t('%name must be lower than or equal to %max.', [
        '%name' => $name,
        '%max' => $element['#max'],
      ]));
    }
    if (isset($element['#step']) && strtolower($element['#step']) != 'any') {

      // Check that the input is an allowed multiple of #step (offset by #min if
      // #min is set).
      $offset = $element['#min'] ?? 0.0;
      if (!NumberUtility::validStep($value, $element['#step'], $offset)) {
        $form_state
          ->setError($element, t('%name is not a valid number.', [
          '%name' => $name,
        ]));
      }
    }
  }

  /**
   * Prepares a #type 'number' render element for input.html.twig.
   *
   * @param array $element
   *   An associative array containing the properties of the element.
   *   Properties used: #title, #value, #description, #min, #max, #placeholder,
   *   #required, #attributes, #step, #size.
   *
   * @return array
   *   The $element with prepared variables ready for input.html.twig.
   */
  public static function preRenderNumber($element) {
    $element['#attributes']['type'] = 'number';
    Element::setAttributes($element, [
      'id',
      'name',
      'value',
      'step',
      'min',
      'max',
      'placeholder',
      'size',
    ]);
    static::setAttributes($element, [
      'form-number',
    ]);
    return $element;
  }

}