islandora/includes/breadcrumb.inc

<?php

/**
 * @file
 * This file contains functions to create breadcrumbs on Islandora object pages.
 */

/**
 * Get an array of links to be passed to drupal_set_breadcrumb().
 *
 * This is used for generating the bread-crumbs for the view object page.
 *
 * Each link in the bread-crumbs represents a member of the given objects
 * ancestry which is identified by any of the following RELS-EXT terms
 * (isMemberOf,isMemberOfCollection,isPartOf,isConstituentOf).
 *
 * @param AbstractObject $object
 *   An object whose ancestry will be mapped to bread-crumbs.
 *
 * @see drupal_set_breadcrumb()
 *
 * @return array
 *   Array of links, starting with most distant ancestor proceeding up to but
 *   not including the given object. For use in the function
 *   drupal_set_breadcrumb().
 */
function islandora_get_breadcrumbs($object) {
  $breadcrumbs = islandora_get_breadcrumbs_recursive($object->id, $object->repository);
  array_pop($breadcrumbs);
  $context = 'islandora';
  drupal_alter('islandora_breadcrumbs', $breadcrumbs, $context, $object);
  return $breadcrumbs;
}

/**
 * Builds an array of drupal links for use in breadcrumbs.
 *
 * @todo Make fully recursive...
 *
 * @param string $pid
 *   The object id whose parent will be fetched for the next link.
 * @param FedoraRepository $repository
 *   The fedora repository.
 * @param array $context
 *   An associative array of context for internal use when recursing. Currently
 *   only used to track a single value:
 *   - level: The number of child-parent relationships to follow. Defaults to
 *     10.
 *
 * @return array
 *   An array of links representing the breadcrumb trail, "root" first.
 */
function islandora_get_breadcrumbs_recursive($pid, FedoraRepository $repository, array &$context = NULL) {
  // Before executing the query, we have a base case of accessing the top-level
  // collection.
  if ($context === NULL) {
    $context['level'] = 10;
  }

  $root = variable_get('islandora_repository_pid', 'islandora:root');
  if ($pid == $root) {
    $title = 'Islandora Repository';
    $mlid = db_select('menu_links', 'ml')
      ->condition('ml.link_path', 'islandora')
      ->fields('ml', array('mlid'))
      ->execute()
      ->fetchField();

    if ($mlid) {
      $link = menu_link_load($mlid);
      $title = (isset($link['title']) ? $link['title'] : $title);
    }

    return array(
      l(t('Home'), '<front>'),
      l($title, 'islandora'),
    );
  }
  else {

    $query = <<<EOQ
    PREFIX islandora-rels-ext: <http://islandora.ca/ontology/relsext#>
    PREFIX fedora-rels-ext: <info:fedora/fedora-system:def/relations-external#>
    SELECT DISTINCT ?object ?label
    FROM <#ri>
    WHERE {
        <info:fedora/!pid> ?parentship_predicate ?object;
        <fedora-model:label> ?label .
        ?object <fedora-model:state> <fedora-model:Active>
        .
        !optionals
        !filters
          }
        !order
EOQ;

    $query_optionals = (array) module_invoke('islandora_xacml_api', 'islandora_basic_collection_get_query_optionals', 'view');
    $query_filters = (array) module_invoke('islandora_xacml_api', 'islandora_basic_collection_get_query_filters');
    $filter_map = function ($filter) {
      return "FILTER($filter)";
    };
    $compound_object_predicate = variable_get('islandora_compound_object_relationship', 'isConstituentOf');
    $parentship_predicate_filters = "sameTerm(?parentship_predicate, <fedora-rels-ext:isPartOf>) || sameTerm(?parentship_predicate, <fedora-rels-ext:{$compound_object_predicate}>)";
    $parentship_predicate_filters .= " || sameTerm(?parentship_predicate, <fedora-rels-ext:isMemberOfCollection>) || sameTerm(?parentship_predicate, <fedora-rels-ext:isMemberOf>)";
    $query_filters[] = $parentship_predicate_filters;
    $query_order = "ORDER BY DESC(?label)";
    $query = format_string($query, array(
      '!optionals' => !empty($query_optionals) ? ('OPTIONAL {{' . implode('} UNION {', $query_optionals) . '}}') : '',
      '!filters' => implode(' ', array_map($filter_map, $query_filters)),
      '!order' => $query_order,
    ));
    $query = format_string($query, array(
      '!pid' => $pid,
    ));

    $results = $repository->ri->sparqlQuery($query, 'unlimited');

    if (count($results) > 0 && $context['level'] > 0) {
      $parent = $results[0]['object']['value'];
      $this_label = $results[0]['label']['value'];

      if (empty($this_label)) {
        $this_label = t('-');
      }

      $context['level']--;
      return array_merge(islandora_get_breadcrumbs_recursive($parent, $repository, $context), array(
        l($this_label, "islandora/object/$pid"),
      ));
    }
    else {
      // Add an non-link, as we don't know how to get back to the root, and
      // render the last two links and break (on the next pass).
      return array_merge(
        islandora_get_breadcrumbs_recursive($root, $repository, $context),
        array('...')
      );
    }
  }
}