facets-8.x-1.x-dev/modules/facets_exposed_filters/facets_exposed_filters.module

<?php

/**
 * @file
 * Contains facets_exposed_filters.module.
 */

use Drupal\Core\Block\BlockPluginInterface;
use Drupal\search_api\Entity\Index;
use Drupal\search_api\Plugin\views\query\SearchApiQuery;
use Drupal\search_api\Query\QueryInterface;
use Drupal\views\Plugin\Block\ViewsExposedFilterBlock;
use Drupal\views\Plugin\views\filter\FilterPluginBase;
use Drupal\views\ViewExecutable;

/**
 * Implements hook_views_data_alter().
 */
function facets_exposed_filters_views_data_alter(array &$data) {
  /** @var \Drupal\search_api\IndexInterface $index */
  foreach (Index::loadMultiple() as $index) {
    $fields = $index->getFields();
    foreach ($fields as $field) {
      // @todo Ensure the field has as least one query type.
      $indexed_fields[$field->getFieldIdentifier()] = $field->getLabel() . ' (' . $field->getPropertyPath() . ')';
      $data['search_api_index_' . $index->id()]['facets_' . $field->getFieldIdentifier()] = [
        'title' => $field->getLabel() . ' (' . $field->getFieldIdentifier() . ')',
        'help' => t('Facets enabled filter. Available options will narrow down based on resultset.', ['@label' => $field->getLabel() . ' (' . $field->getFieldIdentifier() . ')']),
        'filter' => [
          'id' => 'facets_filter',
          'search_api_field_label' => $field->getLabel(),
          'search_api_field_identifier' => $field->getFieldIdentifier(),
        ],
        'group' => t('Facets'),
      ];
    }
  }
}

/**
 * Implements hook_search_api_query_alter().
 */
function facets_exposed_filters_search_api_query_alter(QueryInterface $query) {
  $view = $query->getOption('search_api_view');
  if (!$view || (!$view->exposed_widgets && isset($view->display_handler) && !$view->display_handler->getOption('exposed_block'))) {
    return;
  }

  $query_search_api_facets_options = [];
  // Add all facets_filter filters to the search api query as facet.
  foreach ($view->filter as $filter) {
    if ($filter->getPluginId() == "facets_filter") {
      $configuration = $filter->getConfiguration();
      $field_identifier = $configuration["search_api_field_identifier"];

      $query_search_api_facets_options[$field_identifier] = [
        'field' => $field_identifier,
        'limit' => $filter->options["facet"]["hard_limit"] ?? 0,
        'operator' => $filter->options["facet"]["query_operator"],
        'min_count' => $filter->options["facet"]["min_count"],
        'missing' => FALSE,
        // @todo Investigate if this property (query_type) is used.
        'query_type' => 'search_api_string',
      ];
    }
  }
  if ($query_search_api_facets_options) {
    $options = &$query->getOptions();
    $options['search_api_facets'] = $query_search_api_facets_options;
  }
}

/**
 * Callback to remove validation to ensure non-existing values are allowed.
 */
function facets_exposed_filters_remove_validation($element, $form) {
  // Because facet options get limited while filtering, we need to allow values
  // which are not in the options list.
  unset($element["#needs_validation"]);
  return $element;
}

/**
 * Implements hook_views_post_execute().
 */
function facets_exposed_filters_views_post_execute(ViewExecutable $view) {
  // Skip if no exposed widgets are present and we are not using exposed block.
  if (!$view->exposed_widgets && !$view->display_handler->getOption('exposed_block')) {
    return;
  }

  $query = $view->getQuery();
  // If query is not instance off SearchApiQuery, not supported.
  if (!$query instanceof SearchApiQuery) {
    return;
  }
  $search_api_results = $query->getSearchApiResults();
  $search_api_facets = $search_api_results->getExtraData('search_api_facets');
  $view->facets_query_post_execute = TRUE;

  // If we have facet results, attach them. If no results are returned, we still
  // need to rerender, as there can still be active filters (without results).
  if ($search_api_facets) {
    // Attach facet results to views, so we can use them in FacetsFilter.
    foreach ($view->filter as $search_api_id => $filter) {
      if ($filter->getPluginId() == 'facets_filter') {
        $configuration = $filter->getConfiguration();
        if (isset($search_api_facets[$configuration["search_api_field_identifier"]])) {
          $view->filter[$search_api_id]->facet_results = $search_api_facets[$configuration["search_api_field_identifier"]];
        }
      }
    }
  }

  // Re-render views exposed form with the facet results now available.
  $exposed_form = $view->display_handler->getPlugin('exposed_form');
  $view->exposed_widgets = $exposed_form->renderExposedForm();
}

/**
 * Implements hook_views_filters_summary_info_alter().
 */
function facets_exposed_filters_views_filters_summary_info_alter(array &$info, FilterPluginBase $filter) {
  if ($filter->getPluginId() === 'facets_filter') {
    $values = [];
    foreach ($filter->value as $raw_value) {
      if ($facet_summary_item = facets_exposed_filters_get_nested_summary_value($filter->facet_results, $raw_value)) {
        $values[] = $facet_summary_item;
      }
    }
    $info['value'] = $values;
  }
}

/**
 * Helper function for hierarchical values.
 */
function facets_exposed_filters_get_nested_summary_value($results, $raw_value) {
  foreach ($results as $result) {
    if ($result->getRawValue() == $raw_value) {
      return [
        'id' => $result->getRawValue(),
        'raw' => $result->getRawValue(),
        'value' => $result->getDisplayValue(),
      ];
    }
    // Nested check for hierarchy support.
    if ($facet_summary_item = facets_exposed_filters_get_nested_summary_value($result->getChildren(), $raw_value)) {
      return $facet_summary_item;
    }
  }
  return FALSE;
}

/**
 * Helper function to retrieve (and set) processed facets.
 */
function facets_exposed_filters_get_processed_facet($view_id, $display_id, $filter_id, $processed_facet = NULL) {
  $facet_results = &drupal_static(__FUNCTION__);
  if ($processed_facet) {
    $facet_results[$view_id][$display_id][$filter_id] = $processed_facet;
  }
  if (isset($facet_results[$view_id][$display_id][$filter_id])) {
    return $facet_results[$view_id][$display_id][$filter_id];
  }
  return NULL;
}

/**
 * Implements hook_block_build_alter().
 */
function facets_exposed_filters_block_build_alter(array &$build, BlockPluginInterface $block) {
  // Exposed filter blocks can be placed on any page. We need to ensure that the
  // view is executed when the block is rendered and has Facet filters.
  if ($block instanceof ViewsExposedFilterBlock) {
    $view = $block->getViewExecutable();
    $view->initHandlers();
    foreach ($view->filter as $filter) {
      if ($filter->getPluginId() == "facets_filter") {
        $filter_id = $filter->options["id"];
        $display = $view->current_display;
        $processed_facet = facets_exposed_filters_get_processed_facet($view->id(), $display, $filter_id);
        if (!$processed_facet) {
          // The facet has not been processed.
          $view->execute($display);
        }
        break;
      }
    }
  }
}