<?php

/**
 * @file
 * Runs a IIIF content search in Mirador on load from a passed search term.
 */

use Drupal\advanced_search\AdvancedSearchQuery;
use Drupal\advanced_search\AdvancedSearchQueryTerm;
use Drupal\views\ViewExecutable;

/**
 * Query string parameter used to carry the search term to the item page.
 *
 * Matches the identifier used by the search_in_hocr view.
 */
const MIRADOR_SEARCH_HIGHLIGHT_PARAM = 'search_api_fulltext';

/**
 * Views whose item links should carry the search term.
 */
const MIRADOR_SEARCH_HIGHLIGHT_VIEWS = ['solr_search_content'];

/**
 * Implements hook_views_pre_render().
 *
 * Appends the search term to "Link this field to its item" links so the item
 * page knows what was searched for.
 */
function mirador_search_highlight_views_pre_render(ViewExecutable $view) {
  if (!in_array($view->id(), MIRADOR_SEARCH_HIGHLIGHT_VIEWS, TRUE)) {
    return;
  }
  $keys = _mirador_search_highlight_get_keys($view);
  if ($keys === '') {
    return;
  }

  foreach ($view->field as $handler) {
    if (!empty($handler->options['link_to_item'])) {
      // Search API items are merged with $options['alter'] when rendered as
      // links, and an explicit 'query' replaces the item URL's query.
      // UrlHelper::buildQuery() encodes the value before Views token
      // replacement, so user input is never treated as Twig.
      $handler->options['alter']['query'] = [MIRADOR_SEARCH_HIGHLIGHT_PARAM => $keys];
    }
  }
}

/**
 * Gets the search term the view was run with.
 *
 * @param \Drupal\views\ViewExecutable $view
 *   The search view.
 *
 * @return string
 *   The search term, or an empty string if there is none.
 */
function _mirador_search_highlight_get_keys(ViewExecutable $view) {
  // Advanced Search passes terms as a[N][v] and writes them straight into the
  // Solr query, so the Search API query never has keys set. Read the terms
  // the same way it does, skipping excluded ("IS NOT") terms.
  if (class_exists(AdvancedSearchQuery::class) && ($request = $view->getRequest())) {
    $values = [];
    foreach ((new AdvancedSearchQuery())->getTerms($request) as $term) {
      if ($term->getInclude()) {
        $values[] = trim((string) ($term->toQueryParams()[AdvancedSearchQueryTerm::VALUE_QUERY_PARAMETER] ?? ''));
      }
    }
    $keys = implode(' ', array_filter($values, 'strlen'));
    if ($keys !== '') {
      return $keys;
    }
  }

  // Fall back to a plain Search API fulltext filter. Parse modes may turn the
  // keys into an array; only the raw string is useful to Mirador.
  if (method_exists($view->query, 'getOriginalKeys')) {
    $keys = $view->query->getOriginalKeys();
    if (is_string($keys)) {
      return trim($keys);
    }
  }
  return '';
}

/**
 * Implements hook_preprocess_HOOK() for mirador.
 *
 * Runs after template_preprocess_mirador(), so mirador_view_id is already the
 * unique ID used as the drupalSettings viewer key.
 */
function mirador_search_highlight_preprocess_mirador(&$variables) {
  // Vary the cached viewer by the search term, otherwise the first term
  // searched would be cached and shown to everyone viewing this item.
  $variables['#cache']['contexts'][] = 'url.query_args:' . MIRADOR_SEARCH_HIGHLIGHT_PARAM;

  $term = \Drupal::request()->query->get(MIRADOR_SEARCH_HIGHLIGHT_PARAM, '');
  $term = is_string($term) ? trim($term) : '';
  if ($term === '') {
    return;
  }
  $selector = '#' . $variables['mirador_view_id'];
  $variables['#attached']['drupalSettings']['mirador']['viewers'][$selector]['windows'][0]['defaultSearchQuery'] = mb_substr($term, 0, 256);
}