class Combine

class Combine extends StringFilter {
  
  /**
   * @var \Drupal\views\Plugin\views\query\QueryPluginBase
   */
  public $query;
  protected function defineOptions() {
    $options = parent::defineOptions();
    $options['fields'] = [
      'default' => [],
    ];
    return $options;
  }
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);
    $this->view
      ->initStyle();
    // Allow to choose all fields as possible
    if ($this->view->style_plugin
      ->usesFields()) {
      $options = [];
      foreach ($this->view->display_handler
        ->getHandlers('field') as $name => $field) {
        // Only allow clickSortable fields. Fields without clickSorting will
        // probably break in the Combine filter.
        if ($field->clickSortable()) {
          $options[$name] = $field->adminLabel(TRUE);
        }
      }
      if ($options) {
        $form['fields'] = [
          '#type' => 'select',
          '#title' => $this->t('Choose fields to combine for filtering'),
          '#description' => $this->t("This filter doesn't work for very special field handlers."),
          '#multiple' => TRUE,
          '#options' => $options,
          '#default_value' => $this->options['fields'],
        ];
      }
      else {
        $form_state->setErrorByName('', $this->t('You have to add some fields to be able to use this filter.'));
      }
    }
  }
  public function query() {
    $this->view
      ->_build('field');
    $fields = [];
    // Only add the fields if they have a proper field and table alias.
    foreach ($this->options['fields'] as $id) {
      // Overridden fields can lead to fields missing from a display that are
      // still set in the non-overridden combined filter.
      if (!isset($this->view->field[$id])) {
        // If fields are no longer available that are needed to filter by, make
        // sure no results are shown to prevent displaying more then intended.
        $this->view->build_info['fail'] = TRUE;
        continue;
      }
      $field = $this->view->field[$id];
      // Always add the table of the selected fields to be sure a table alias exists.
      $field->ensureMyTable();
      if (!empty($field->tableAlias) && !empty($field->realField)) {
        $fields[] = "{$field->tableAlias}.{$field->realField}";
      }
    }
    if ($fields) {
      // We do not use the CONCAT_WS operator when there is only a single field.
      // Using the CONCAT_WS operator with a single field is not a problem for
      // the by core supported databases. Only the MS SQL Server requires the
      // CONCAT_WS operator to be used with at least three arguments.
      if (count($fields) == 1) {
        $expression = reset($fields);
      }
      else {
        // Multiple fields are separated by 3 spaces so that so that search
        // strings that contain spaces are still only matched to single field
        // values and not to multi-field values that exist only because we do
        // the concatenation/LIKE trick.
        $expression = implode(", ' ', ", $fields);
        $expression = "CONCAT_WS(' ', {$expression})";
      }
      $info = $this->operators();
      if (!empty($info[$this->operator]['method'])) {
        $this->{$info[$this->operator]['method']}($expression);
      }
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function validate() {
    $errors = parent::validate();
    if ($this->displayHandler
      ->usesFields()) {
      $fields = $this->displayHandler
        ->getHandlers('field');
      foreach ($this->options['fields'] as $id) {
        if (!isset($fields[$id])) {
          // Combined field filter only works with fields that are in the field
          // settings.
          $errors[] = $this->t('Field %field set in %filter is not set in display %display.', [
            '%field' => $id,
            '%filter' => $this->adminLabel(),
            '%display' => $this->displayHandler->display['display_title'],
          ]);
          break;

        }
        elseif (!$fields[$id]->clickSortable()) {
          // Combined field filter only works with simple fields. If the field
          // is not click sortable we can assume it is not a simple field.
          // @todo change this check to isComputed. See
          // https://www.drupal.org/node/2349465
          $errors[] = $this->t('Field %field set in %filter is not usable for this filter type. Combined field filter only works for simple fields.', [
            '%field' => $fields[$id]->adminLabel(),
            '%filter' => $this->adminLabel(),
          ]);
        }
      }
    }
    else {
      $errors[] = $this->t('%display: %filter can only be used on displays that use fields. Set the style or row format for that display to one using fields to use the combine field filter.', [
        '%display' => $this->displayHandler->display['display_title'],
        '%filter' => $this->adminLabel(),
      ]);
    }
    return $errors;
  }
  
  /**
   * {@inheritdoc}
   */
  public function opEqual($expression) {
    // By default, things like opEqual uses add_where, that doesn't support
    // complex expressions, so override opEqual (and all operators below).
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator($this->operator());
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => $this->value,
    ]);
  }
  protected function opContains($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('LIKE');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => '%' . $this->connection
        ->escapeLike($this->value) . '%',
    ]);
  }
  
  /**
   * Filters by one or more words.
   *
   * By default opContainsWord uses add_where, that doesn't support complex
   * expressions.
   *
   * @param string $expression
   *   The expression to add to the query.
   */
  protected function opContainsWord($expression) {
    $placeholder = $this->placeholder();
    // Don't filter on empty strings.
    if (empty($this->value)) {
      return;
    }
    // Match all words separated by spaces or sentences encapsulated by double
    // quotes.
    preg_match_all(static::WORDS_PATTERN, ' ' . $this->value, $matches, PREG_SET_ORDER);
    // Switch between the 'word' and 'allwords' operator.
    $type = $this->operator == 'word' ? 'OR' : 'AND';
    $group = $this->query
      ->setWhereGroup($type);
    $operator = $this->getConditionOperator('LIKE');
    foreach ($matches as $match_key => $match) {
      $temp_placeholder = $placeholder . '_' . $match_key;
      // Clean up the user input and remove the sentence delimiters.
      $word = trim($match[2], ',?!();:-"');
      $this->query
        ->addWhereExpression($group, "{$expression} {$operator} {$temp_placeholder}", [
        $temp_placeholder => '%' . $this->connection
          ->escapeLike($word) . '%',
      ]);
    }
  }
  protected function opStartsWith($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('LIKE');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => $this->connection
        ->escapeLike($this->value) . '%',
    ]);
  }
  protected function opNotStartsWith($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('NOT LIKE');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => $this->connection
        ->escapeLike($this->value) . '%',
    ]);
  }
  protected function opEndsWith($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('LIKE');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => '%' . $this->connection
        ->escapeLike($this->value),
    ]);
  }
  protected function opNotEndsWith($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('NOT LIKE');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => '%' . $this->connection
        ->escapeLike($this->value),
    ]);
  }
  protected function opNotLike($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('NOT LIKE');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => '%' . $this->connection
        ->escapeLike($this->value) . '%',
    ]);
  }
  protected function opRegex($expression) {
    $placeholder = $this->placeholder();
    $operator = $this->getConditionOperator('REGEXP');
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator} {$placeholder}", [
      $placeholder => $this->value,
    ]);
  }
  protected function opEmpty($expression) {
    if ($this->operator == 'empty') {
      $operator = "IS NULL";
    }
    else {
      $operator = "IS NOT NULL";
    }
    $this->query
      ->addWhereExpression($this->options['group'], "{$expression} {$operator}");
  }

}