class RearrangeFilter

class RearrangeFilter extends ViewsFormBase {
    
    /**
     * Constructs a new RearrangeFilter object.
     */
    public function __construct($type = NULL) {
        $this->setType($type);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormKey() {
        return 'rearrange-filter';
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'views_ui_rearrange_filter_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $view = $form_state->get('view');
        $display_id = $form_state->get('display_id');
        $type = 'filter';
        $types = ViewExecutable::getHandlerTypes();
        $executable = $view->getExecutable();
        if (!$executable->setDisplay($display_id)) {
            $form['markup'] = [
                '#markup' => $this->t('Invalid display id @display', [
                    '@display' => $display_id,
                ]),
            ];
            return $form;
        }
        $display = $executable->displayHandlers
            ->get($display_id);
        $form['#title'] = Html::escape($display->display['display_title']) . ': ';
        $form['#title'] .= $this->t('Rearrange @type', [
            '@type' => $types[$type]['ltitle'],
        ]);
        $form['#section'] = $display_id . 'rearrange-item';
        if ($display->defaultableSections($types[$type]['plural'])) {
            $section = $types[$type]['plural'];
            $form_state->set('section', $section);
            views_ui_standard_display_dropdown($form, $form_state, $section);
        }
        if (!empty($view->form_cache)) {
            $groups = $view->form_cache['groups'];
            $handlers = $view->form_cache['handlers'];
        }
        else {
            $groups = $display->getOption('filter_groups');
            $handlers = $display->getOption($types[$type]['plural']);
        }
        $count = 0;
        // Get relationship labels
        $relationships = [];
        foreach ($display->getHandlers('relationship') as $id => $handler) {
            $relationships[$id] = $handler->adminLabel();
        }
        $group_options = [];
        
        /**
         * Filter groups is an array that contains:
         * array(
         *   'operator' => 'and' || 'or',
         *   'groups' => array(
         *     $group_id => 'and' || 'or',
         *   ),
         * );
         */
        $grouping = count(array_keys($groups['groups'])) > 1;
        $form['filter_groups']['#tree'] = TRUE;
        $form['filter_groups']['operator'] = [
            '#type' => 'select',
            '#options' => [
                'AND' => $this->t('And'),
                'OR' => $this->t('Or'),
            ],
            '#default_value' => $groups['operator'],
            '#attributes' => [
                'class' => [
                    'warning-on-change',
                ],
            ],
            '#title' => $this->t('Operator to use on all groups'),
            '#description' => $this->t('Either "group 0 AND group 1 AND group 2" or "group 0 OR group 1 OR group 2", etc'),
            '#access' => $grouping,
        ];
        $form['remove_groups']['#tree'] = TRUE;
        foreach ($groups['groups'] as $id => $group) {
            $form['filter_groups']['groups'][$id] = [
                '#title' => $this->t('Operator'),
                '#type' => 'select',
                '#options' => [
                    'AND' => $this->t('And'),
                    'OR' => $this->t('Or'),
                ],
                '#default_value' => $group,
                '#attributes' => [
                    'class' => [
                        'warning-on-change',
                    ],
                ],
            ];
            // To prevent a notice.
            $form['remove_groups'][$id] = [];
            if ($id != 1) {
                $form['remove_groups'][$id] = [
                    '#type' => 'submit',
                    '#value' => $this->t('Remove group @group', [
                        '@group' => $id,
                    ]),
                    '#id' => "views-remove-group-{$id}",
                    '#attributes' => [
                        'class' => [
                            'views-remove-group',
                        ],
                    ],
                    '#group' => $id,
                    '#ajax' => [
                        'url' => NULL,
                    ],
                ];
            }
            $group_options[$id] = $id == 1 ? $this->t('Default group') : $this->t('Group @group', [
                '@group' => $id,
            ]);
            $form['#group_renders'][$id] = [];
        }
        $form['#group_options'] = $group_options;
        $form['#groups'] = $groups;
        // We don't use getHandlers() because we want items without handlers to
        // appear and show up as 'broken' so that the user can see them.
        $form['filters'] = [
            '#tree' => TRUE,
        ];
        foreach ($handlers as $id => $field) {
            // If the group does not exist, move the filters to the default group.
            if (empty($field['group']) || empty($groups['groups'][$field['group']])) {
                $field['group'] = 1;
            }
            $handler = $display->getHandler($type, $id);
            if ($grouping && $handler && !$handler->canGroup()) {
                $field['group'] = 'ungroupable';
            }
            // If not grouping and the handler is set ungroupable, move it back to
            // the default group to prevent weird errors from having it be in its
            // own group:
            if (!$grouping && $field['group'] == 'ungroupable') {
                $field['group'] = 1;
            }
            // Place this item into the proper group for rendering.
            $form['#group_renders'][$field['group']][] = $id;
            $form['filters'][$id]['weight'] = [
                '#title' => t('Weight for @id', [
                    '@id' => $id,
                ]),
                '#title_display' => 'invisible',
                '#type' => 'textfield',
                '#default_value' => ++$count,
                '#size' => 8,
            ];
            $form['filters'][$id]['group'] = [
                '#title' => t('Group for @id', [
                    '@id' => $id,
                ]),
                '#title_display' => 'invisible',
                '#type' => 'select',
                '#options' => $group_options,
                '#default_value' => $field['group'],
                '#attributes' => [
                    'class' => [
                        'views-region-select',
                        'views-region-' . $id,
                    ],
                ],
                '#access' => $field['group'] !== 'ungroupable',
            ];
            if ($handler) {
                $name = $handler->adminLabel() . ' ' . $handler->adminSummary();
                if (!empty($field['relationship']) && !empty($relationships[$field['relationship']])) {
                    $name = '(' . $relationships[$field['relationship']] . ') ' . $name;
                }
                $form['filters'][$id]['name'] = [
                    '#markup' => $name,
                ];
            }
            else {
                $form['filters'][$id]['name'] = [
                    '#markup' => $this->t('Broken field @id', [
                        '@id' => $id,
                    ]),
                ];
            }
            $form['filters'][$id]['removed'] = [
                '#title' => t('Remove @id', [
                    '@id' => $id,
                ]),
                '#title_display' => 'invisible',
                '#type' => 'checkbox',
                '#id' => 'views-removed-' . $id,
                '#attributes' => [
                    'class' => [
                        'views-remove-checkbox',
                    ],
                ],
                '#default_value' => 0,
            ];
        }
        $view->getStandardButtons($form, $form_state, 'views_ui_rearrange_filter_form');
        $form['actions']['add_group'] = [
            '#type' => 'submit',
            '#value' => $this->t('Create new filter group'),
            '#id' => 'views-add-group',
            '#group' => 'add',
            '#attributes' => [
                'class' => [
                    'views-add-group',
                ],
            ],
            '#ajax' => [
                'url' => NULL,
            ],
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
        $types = ViewExecutable::getHandlerTypes();
        $view = $form_state->get('view');
        $display =& $view->getExecutable()->displayHandlers
            ->get($form_state->get('display_id'));
        $remember_groups = [];
        if (!empty($view->form_cache)) {
            $old_fields = $view->form_cache['handlers'];
        }
        else {
            $old_fields = $display->getOption($types['filter']['plural']);
        }
        $groups = $form_state->getValue('filter_groups');
        // Whatever button was clicked, re-calculate field information.
        $new_fields = $order = [];
        // Make an array with the weights
        foreach ($form_state->getValue('filters') as $field => $info) {
            // add each value that is a field with a weight to our list, but only if
            // it has had its 'removed' checkbox checked.
            if (is_array($info) && empty($info['removed'])) {
                if (isset($info['weight'])) {
                    $order[$field] = $info['weight'];
                }
                if (isset($info['group'])) {
                    $old_fields[$field]['group'] = $info['group'];
                    $remember_groups[$info['group']][] = $field;
                }
            }
        }
        // Sort the array
        asort($order);
        // Create a new list of fields in the new order.
        foreach (array_keys($order) as $field) {
            $new_fields[$field] = $old_fields[$field];
        }
        // If the #group property is set on the clicked button, that means we are
        // either adding or removing a group, not actually updating the filters.
        $triggering_element = $form_state->getTriggeringElement();
        if (!empty($triggering_element['#group'])) {
            if ($triggering_element['#group'] == 'add') {
                // Add a new group
                $groups['groups'][] = 'AND';
            }
            else {
                // Renumber groups above the removed one down.
                foreach (array_keys($groups['groups']) as $group_id) {
                    if ($group_id >= $triggering_element['#group']) {
                        $old_group = $group_id + 1;
                        if (isset($groups['groups'][$old_group])) {
                            $groups['groups'][$group_id] = $groups['groups'][$old_group];
                            if (isset($remember_groups[$old_group])) {
                                foreach ($remember_groups[$old_group] as $id) {
                                    $new_fields[$id]['group'] = $group_id;
                                }
                            }
                        }
                        else {
                            // If this is the last one, just unset it.
                            unset($groups['groups'][$group_id]);
                        }
                    }
                }
            }
            // Update our cache with values so that cancel still works the way
            // people expect.
            $view->form_cache = [
                'key' => 'rearrange-filter',
                'groups' => $groups,
                'handlers' => $new_fields,
            ];
            // Return to this form except on actual Update.
            $view->addFormToStack('rearrange-filter', $form_state->get('display_id'), 'filter');
        }
        else {
            // The actual update button was clicked. Remove the empty groups, and
            // renumber them sequentially.
            ksort($remember_groups);
            $groups['groups'] = static::arrayKeyPlus(array_values(array_intersect_key($groups['groups'], $remember_groups)));
            // Change the 'group' key on each field to match. Here, $mapping is an
            // array whose keys are the old group numbers and whose values are the new
            // (sequentially numbered) ones.
            $mapping = array_flip(static::arrayKeyPlus(array_keys($remember_groups)));
            foreach ($new_fields as &$new_field) {
                $new_field['group'] = $mapping[$new_field['group']];
            }
            // Write the changed handler values.
            $display->setOption($types['filter']['plural'], $new_fields);
            $display->setOption('filter_groups', $groups);
            if (isset($view->form_cache)) {
                unset($view->form_cache);
            }
        }
        // Store in cache.
        $view->cacheSet();
    }
    
    /**
     * Adds one to each key of an array.
     *
     * For example array(0 => 'foo') would be array(1 => 'foo').
     *
     * @param array $array
     *   The array to increment keys on.
     *
     * @return array
     *   The array with incremented keys.
     */
    public static function arrayKeyPlus($array) {
        $keys = array_keys($array);
        // Sort the keys in reverse order so incrementing them doesn't overwrite any
        // existing keys.
        rsort($keys);
        foreach ($keys as $key) {
            $array[$key + 1] = $array[$key];
            unset($array[$key]);
        }
        // Sort the keys back to ascending order.
        ksort($array);
        return $array;
    }

}