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();
        $this->query
            ->addWhereExpression($this->options['group'], "{$expression} REGEXP {$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}");
    }

}