ting_search_context.module

<?php

/**
 * @file
 * Module file for the Ting search context module.
 */

define('TING_SEARCH_CONTEXT_MAX_RATING', 10);

include_once 'ting_search_context.features.inc';

/**
 * Implements hook_menu().
 */
function ting_search_context_menu() {
  $items['admin/content/ting-search-context'] = array(
    'title' => 'Search context',
    'description' => 'Manage the state of the context rating system.',
    'page callback' => 'ting_search_context_admin_rate_nodes',
    'access arguments' => array('administer ting search context ratings'),
    'type' => MENU_LOCAL_TASK | MENU_NORMAL_ITEM,
    'file' => 'ting_search_context.admin.inc',
  );
  $items['ting/ting_search_context/content/ajax'] = array(
    'title' => 'Show content related to search context in carousel',
    'page callback' => 'ting_search_context_content',
    'access arguments' => array('access content'),
    'file' => 'ting_search_context.pages.inc',
    'type' => MENU_CALLBACK,
  );
  $items['admin/config/ting/ting-search-context'] = array(
    'title' => 'Search context',
    'description' => 'Manage settings for the Ting search context module.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('ting_search_context_admin_settings_form'),
    'access arguments' => array('administer ting search context'),
    'file' => 'ting_search_context.admin.inc',
  );
  $items['admin/config/ting/ting-search-context/frontend'] = array(
    'title' => 'Frontend',
    'description' => 'Choose location of related content on search page',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/config/ting/ting-search-context/fallback-images'] = array(
    'title' => 'Fallback images',
    'description' => 'Select which images to use when showing rated content.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('ting_search_context_admin_fallback_images'),
    'access arguments' => array('administer site configuration'),
    'type' => MENU_LOCAL_TASK,
    'file' => 'ting_search_context.admin.inc',
    'weight' => -5,
  );
  $items['admin/config/ting/ting-search-context/contexts'] = array(
    'title' => 'Contexts',
    'description' => 'Create new contexts and edit/delete existing ones',
    'page callback' => 'ting_search_context_admin_contexts',
    'access arguments' => array('administer ting search context'),
    'type' => MENU_LOCAL_TASK,
    'file' => 'ting_search_context.admin.inc',
  );
  $items['admin/config/ting/ting-search-context/contexts/add'] = array(
    'title' => 'Add context',
    'description' => 'Add a new subject or search type context to the system',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('ting_search_context_admin_context_form_add'),
    'access arguments' => array('administer ting search context'),
    'type' => MENU_LOCAL_ACTION,
    'file' => 'ting_search_context.admin.inc',
  );
  $items['admin/config/ting/ting-search-context/contexts/%ting_search_context/edit'] = array(
    'title' => 'Edit context',
    'description' => 'Edit an existing subject or search type context',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('ting_search_context_admin_context_form_edit', 5),
    'access arguments' => array('administer ting search context'),
    'file' => 'ting_search_context.admin.inc',
  );
  $items['admin/config/ting/ting-search-context/contexts/%ting_search_context/delete'] = array(
    'title' => 'Delete context',
    'description' => 'Delete a subject or search type context',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('ting_search_context_admin_context_delete_confirm_form', 5),
    'access arguments' => array('administer ting search context'),
    'file' => 'ting_search_context.admin.inc',
  );
  $items['ting-search-context/autocomplete'] = array(
    'title' => 'Context autocomplete',
    'page callback' => 'ting_search_context_autocomplete',
    'access arguments' => array('administer ting search context ratings'),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_theme().
 */
function ting_search_context_theme($existing, $type, $theme, $path) {
  return array(
    'ting_search_context' => array(
      'variables' => array('context' => NULL, 'position' => NULL),
      'template' => 'templates/ting_search_context',
      'file' => 'ting_search_context.theme.inc',
    ),
    'ting_search_context_content' => array(
      'variables' => array('node' => NULL),
      'template'  => 'templates/ting_search_context_content',
      'file' => 'ting_search_context.theme.inc',
    ),
    'views_view_field__ting_search_context_rate_nodes__title' => array(
      'variables' => array('view' => NULL, 'options' => NULL, 'row' => NULL),
      'template' => 'templates/views-view-field--ting-search-context-rate-nodes--title',
      'base hook' => 'views_views_field',
      'preprocess functions' => array(
        'template_preprocess',
        'template_preprocess_views_view_field',
      ),
    ),
  );
}

/**
 * Implements hook_forms().
 */
function ting_search_context_forms() {
  $forms = array();
  $forms['ting_search_context_admin_context_form_add'] = array(
    'callback' => 'ting_search_context_admin_context_form',
  );
  $forms['ting_search_context_admin_context_form_edit'] = array(
    'callback' => 'ting_search_context_admin_context_form',
  );
  return $forms;
}

/**
 * Implements hook_ctools_plugin_directory().
 *
 * It simply tells panels where to find the .inc files that define various
 * args, contexts, content_types.
 */
function ting_search_context_ctools_plugin_directory($module, $plugin) {
  if ($module == 'ctools' && !empty($plugin)) {
    return "plugins/$plugin";
  }
}

/**
 * Implements hook_permission().
 */
function ting_search_context_permission() {
  return array(
    'administer ting search context ratings' => array(
      'title' => t('Administer ratings'),
      'description' => t('Rate and unrate nodes in search contexts.'),
    ),
    'administer ting search context' => array(
      'title' => t('Administer ting search context'),
      'description' => t('Administer contexts and settings for Ting search context.'),
    ),
  );
}

/**
 * Implements hook_secure_permissions().
 */
function ting_search_context_secure_permissions($role) {
  $permissions = array(
    'administrators' => array(
      'administer ting search context ratings',
      'administer ting search context',
      'delete any ding_search_context_link content',
      'delete own ding_search_context_link content',
      'create ding_search_context_link content',
      'edit own ding_search_context_link content',
      'edit any ding_search_context_link content',
    ),
    'local administrator' => array(
      'administer ting search context ratings',
      'administer ting search context',
      'delete any ding_search_context_link content',
      'delete own ding_search_context_link content',
      'create ding_search_context_link content',
      'edit own ding_search_context_link content',
      'edit any ding_search_context_link content',
    ),
    'editor' => array(
      'administer ting search context ratings',
      'delete any ding_search_context_link content',
      'delete own ding_search_context_link content',
      'create ding_search_context_link content',
      'edit own ding_search_context_link content',
      'edit any ding_search_context_link content',
    ),
    'local editor' => array(
      'delete own ding_search_context_link content',
      'create ding_search_context_link content',
      'edit own ding_search_context_link content',
      'edit any ding_search_context_link content',
    ),
  );
  if (isset($permissions[$role])) {
    return $permissions[$role];
  }
}

/**
 * Implements hook_ting_pre_execute().
 *
 * To properly determine the context of a search result, we need certain facets
 * to be returned from the well. Here we ensure that they are added to every
 * Ting search request. It won't have any effect on the facetbrowser, since it
 * only adds its own configured facets.
 */
function ting_search_context_ting_pre_execute($request) {
  // Collection requests extends search requests, so we use get_class.
  if (get_class($request) === 'TingClientSearchRequest') {
    $required_facets = array(
      'facet.type' => 'facet.type',
      'facet.category' => 'facet.category',
      'facet.genreCategory' => 'facet.genreCategory',
      'facet.fictionSubject' => 'facet.fictionSubject',
    );

    $facets = array_flip($request->getFacets()) + $required_facets;
    $request->setFacets(array_keys($facets));
  }
}

/**
 * Helper function to get field_name for specified node type.
 */
function ting_search_context_get_image_field_name($node) {
  $field_names = &drupal_static(__FUNCTION__);

  if (!isset($field_names)) {
    $field_names = module_invoke_all('ting_search_context_field_name');
  }

  $type = $node->type;
  return isset($field_names[$type]) ? $field_names[$type] : FALSE;
}

/**
 * Implements hook_ting_search_context_field_name().
 */
function ting_search_context_ting_search_context_field_name() {
  return array(
    'ding_news' => 'field_ding_news_list_image',
    'ding_event' => 'field_ding_event_list_image',
    'ding_page' => 'field_ding_page_list_image',
    // These should probably be moved to respective modules.
    'ding_eresource' => 'field_ding_eresource_list_image',
    'genre_page' => 'field_genre_page_list_image',
    'ding_search_context_link' => 'field_search_context_list_image',
  );
}

/**
 * Handler for the autocomplete field on the VBO-configuration form.
 *
 * Searches for at context by the human-readable name. Will output a JSON-array
 * with the name and the identifying id in paranthesis, so that we can fectch
 * the correct context in the validate handler.
 */
function ting_search_context_autocomplete($string = '') {
  $matches = array();

  $result = db_select('ting_search_context_contexts', 'tsc')
    ->fields('tsc')
    ->condition('name', '%' . db_like($string) . '%', 'LIKE')
  // Note: this could be a setting.
    ->range(0, 10)
    ->execute();

  foreach ($result as $context) {
    $id = $context->context_id;
    $name = check_plain($context->name);
    $matches[$name . " ($id)"] = $name . " ($id)";
  }

  drupal_json_output($matches);
}

/**
 * Implements hook_action_info().
 */
function ting_search_context_action_info() {
  return array(
    'ting_search_context_rate_node_action' => array(
      'type' => 'node',
      'label' => t('Rate a node in the search context rating system'),
      'configurable' => TRUE,
      'vbo_configurable' => TRUE,
      'triggers' => array('any'),
    ),
    'ting_search_context_unrate_node_action' => array(
      'type' => 'node',
      'label' => t('Unrate a node in the search context rating system (completely)'),
      // Appearently we need these to avoid PHP notice.
      'configurable' => FALSE,
      'vbo_configurable' => FALSE,
      'triggers' => array('any'),
    ),
  );
}

/**
 * Callback for our rate node action.
 */
function ting_search_context_rate_node_action(&$node, $context) {
  $search_context = ting_search_context_load($context['context']);
  $rating = $context['rating'];

  // Perform the rating.
  ting_search_context_rate_node($search_context->context_id, $node->nid, $rating);

  $message = t('Rated %node in %context with a rating of %rating', array(
    '%node' => check_plain($node->title),
    '%context' => check_plain($search_context->name),
    '%rating' => $rating,
  ));
  drupal_set_message($message);
}

/**
 * Callback for our unrate node action.
 */
function ting_search_context_unrate_node_action(&$node, $context) {
  // Perform the unrating.
  $num_deleted = ting_search_context_unrate_node($node->nid);

  $message = format_plural($num_deleted,
    'Unrated %node. 1 rating was deleted.',
    'Unrated %node. @count ratings was deleted.',
    array('%node' => check_plain($node->title))
  );
  drupal_set_message($message);
}

/**
 * Form builder.
 *
 * Form builder for VBO per-bulk configuration form and Drupal core standard
 * advanced action form. Enables administrators to select the context and rating
 * for the nodes.
 */
function ting_search_context_rate_node_action_form($settings, &$form_state = NULL) {
  // Setup options arrays for the select-boxes.
  $contexts = ting_search_context_get_all_contexts();
  $context_options = array();
  foreach ($contexts as $context) {
    $context_options[$context->context_id] = $context->name;
  }
  $rating_options = drupal_map_assoc(range(1, TING_SEARCH_CONTEXT_MAX_RATING));

  // Allow the adminstrator to choose between different selection mehods.
  $form_context['method'] = array(
    '#type' => 'radios',
    '#title' => t('Selection method'),
    '#default_value' => 0,
    '#options' => array(0 => t('Selection'), 1 => t('Autocomplete')),
  );
  $form_context['select'] = array(
    '#type' => 'select',
    '#options' => $context_options,
    '#empty_option' => t('- Choose a context -'),
    '#default_value' => isset($settings['context']) ? $settings['context'] : '',
    '#states' => array(
      'visible' => array(
        'input[name="method"]' => array('value' => '0'),
      ),
      'required' => array(
        'input[name="method"]' => array('value' => '0'),
      ),
    ),
  );
  $form_context['autocomplete'] = array(
    '#type' => 'textfield',
    '#title' => t('Search for a context'),
    '#autocomplete_path' => 'ting-search-context/autocomplete',
    '#states' => array(
      'visible' => array(
        'input[name="method"]' => array('value' => '1'),
      ),
      'required' => array(
        'input[name="method"]' => array('value' => '1'),
      ),
    ),
  );

  $form_rating = array(
    '#type' => 'select',
    '#options' => $rating_options,
    '#empty_option' => t('- Choose a rating -'),
    '#default_value' => isset($settings['rating']) ? $settings['rating'] : '',
    '#required' => TRUE,
  );

  $form = array();

  // This is VBO per-bulk configuration form since form_state parameter is
  // passed. In this case we provide a special more user friendly form with
  // the selected nodes displayed.
  if (isset($form_state) && !empty($form_state['selection'])) {
    $form['rating'] = $form_rating;
    $form['rating']['#prefix'] = '<h3>' . t('In what degree (rating):') . '</h3>';
    $selected_nodes = node_load_multiple($form_state['selection']);
    $items = array();
    foreach ($selected_nodes as $node) {
      $items[] = check_plain($node->title);
    }
    $form['selected_nodes'] = array(
      '#theme' => 'item_list',
      '#items' => $items,
      '#title' => t('Does the following content:'),
      '#attributes' => array('class' => 'ting-search-context-selected-nodes'),
    );
    $form['context'] = $form_context;
    $form['context']['#prefix'] = '<h3 class="context-header">' . t('Relate to (select a context) :') . '</h3>';
  }
  // Else it's an advanced action form and we just return a standard form with
  // 2 select-boxes.
  else {
    $form['context']['select']['#title'] = t('Context');
    $form['rating']['#title'] = t('Rating');
    $form['context'] = $form_context;
    $form['rating'] = $form_rating;
  }

  return $form;
}

/**
 * Validate handler for rate node action form.
 */
function ting_search_context_rate_node_action_validate($form, &$form_state) {
  // Autocomplete.
  if ($form_state['values']['method']) {
    $name = $form_state['values']['autocomplete'];
    $matches = array();
    $context_id = 0;

    // Look for the context_id in the paraenthesis at the end of input string.
    $result = preg_match('/\(([0-9]+)\)$/', $name, $matches);
    if ($result) {
      $input_id = $matches[$result];

      // Try to load to see if it exists.
      if (ting_search_context_load($input_id)) {
        $context_id = $input_id;
      }
    }

    if (!empty($context_id)) {
      $form_state['values']['context'] = $context_id;
    }
    else {
      form_set_error('autocomplete', t('No context found for: %name', array(
        '%name' => $name,
      )));
    }
  }
  // Select.
  else {
    // The required states doesn't actually work, since everything is handled
    // on the server. So here we ensure that a context is selected, when using
    // the select selection method.
    // See: https://api.drupal.org/comment/24863#comment-24863
    if (empty($form_state['values']['select'])) {
      form_set_error('select');
    }
    $form_state['values']['context'] = $form_state['values']['select'];
  }
}

/**
 * Submit function for the rate node action form.
 */
function ting_search_context_rate_node_action_submit($form, &$form_state) {
  return array(
    'context' => $form_state['values']['context'],
    'rating' => $form_state['values']['rating'],
  );
}

/**
 * Implements hook_views_bulk_operations_form_alter().
 */
function ting_search_context_views_bulk_operations_form_alter(&$form, &$form_state, $vbo) {
  // Only do something if we're altering our own VBO view.
  if ($vbo->view->name == 'ting_search_context_rate_nodes') {
    // Add CSS here since this is called for both vbo forms.
    $path = drupal_get_path('module', 'ting_search_context');
    $form['#attached']['css'][] = $path . '/css/ting_search_context.admin.css';

    // Add a class if this is the first step (per-bulk form).
    if ($form_state['step'] == 'views_form_views_form') {
      $form['#attributes']['class'][] = 'ting-search-context-rate-nodes-first-step';
    }

    // Alter the confirm form which comes after the per-bulk form.
    elseif ($form_state['step'] == 'views_bulk_operations_confirm_form') {
      $selected_nodes = node_load_multiple($form_state['selection']);
      $items = array();

      // Since VBO isn't using a render array we unset the description and
      // add our own form elements.
      unset($form['description']);

      // Extract operation.
      $operation = '';
      if (isset($form_state['operation'])) {
        $prefix = 'action::';
        $operation = $form_state['operation'];
        if (substr($operation->operationId, 0, strlen($prefix)) === $prefix) {
          $operation = substr($operation->operationId, strlen($prefix));
        }
        else {
          $operation = $operation->operationId;
        }
      }

      // Rate action: show selected nodes, context and rating.
      if ($operation == 'ting_search_context_rate_node_action') {
        $context = ting_search_context_load($form_state['values']['context']);
        $rating = $form_state['values']['rating'];

        foreach ($selected_nodes as $node) {
          $items[] = check_plain($node->title);
        }

        $form['selected_nodes'] = array(
          '#theme' => 'item_list',
          '#items' => $items,
          '#title' => t('You selected the following content:'),
          '#attributes' => array('class' => 'ting-search-context-selected-nodes'),
        );
        $form['selected_context'] = array(
          '#theme' => 'html_tag',
          '#tag' => 'h3',
          '#value' => t('To be rated in the context: %context', array(
            '%context' => $context->name,
          )),
        );
        $form['selected_rating'] = array(
          '#theme' => 'html_tag',
          '#tag' => 'h3',
          '#value' => t('With a rating of: %rating', array(
            '%rating' => $rating,
          )),
        );
      }

      // Unrate action: show all ratings grouped by each selected node.
      elseif ($operation == 'ting_search_context_unrate_node_action') {
        foreach ($selected_nodes as $node) {
          $item = array();
          $item['data'] = '<strong>' . check_plain($node->title) . '</strong>';

          // Loads all ratings for the node.
          $ratings = ting_search_context_ratings_load(NULL, $node->nid);
          foreach ($ratings as $rating) {
            $context = ting_search_context_load($rating->context_id);
            $item['children'][] = check_plain($context->name) . " ($rating->rating)";
          }

          // Add to main list.
          $items[] = $item;
        }

        $form['selected_nodes'] = array(
          '#theme' => 'item_list',
          '#items' => $items,
          '#title' => t('The following ratings will be removed:'),
        );
      }

    }
  }
}

/**
 * Implements hook_form_FORM_ID_alter().
 *
 * Fix for the exposed filter form overlay bug (breaks on submit).
 * See https://www.drupal.org/node/1116326 for more info.
 */
function ting_search_context_form_views_exposed_form_alter(&$form, &$form_state) {
  $name = $form_state['view']->name;

  // Only do something if this is our view.
  if ($name == 'ting_search_context_rate_nodes' || $name == 'ting_search_context_contexts') {
    // If the overlay is being used, add the hidden form element.
    if (isset($_REQUEST['render']) && $_REQUEST['render'] == 'overlay') {
      $form['render'] = array(
        '#type' => 'hidden',
        '#value' => 'overlay',
      );
    }
  }
}

/**
 * Randomly selects nodes rated in the specified context.
 *
 * Randomly selects nodes rated in the specified context, such that nodes with
 * a higher rating has a chance of being selected.
 * Note: Nodes with max rating of 10 will be prefered. This allows
 * administrators to push very relevant content to the users.
 *
 * @param int $context_id
 *   The ID of the context to search in.
 * @param int $count
 *   The max number of nodes to return. Defaults to 5. (optional).
 * @param mixed $node_types
 *   Can either be a string with a single node type, or an array of node types.
 *   Defaults to 'all' which returns nodes of all types. (optional).
 *
 * @return array
 *   An array of node objects keyd by nid.
 */
function ting_search_context_get_nodes($context_id, $count = 5, $node_types = 'all') {
  $return = array();
  // No need to conteniue with the following input.
  if (empty($node_types) || $count < 1) {
    return $return;
  }

  // Setup a common query.
  $query = db_select('node', 'n');
  $nr_alias = $query->join(
        'ting_search_context_nodes_rated',
        'nr',
        'n.nid = %alias.nid'
  );
  $query->addField('n', 'nid', 'nid');
  $query->addField($nr_alias, 'rating', 'rating');
  $query->condition($nr_alias . '.context_id', $context_id)
    ->condition('n.status', 1, '=')
    ->orderRandom()
        // Lets node access modules alter the query.
        // See: https://www.drupal.org/node/310077 and hook_query_TAG_alter().
    ->addTag('node_access');

  // Add constraints on node types if specified.
  if ($node_types !== 'all') {
    $node_types = is_array($node_types) ? $node_types : array($node_types);
    $node_types_condition = db_or();
    foreach ($node_types as $node_type) {
      $node_types_condition->condition('n.type', $node_type);
    }
    $query->condition($node_types_condition);
  }

  // Fetch nodes with max rating.
  $query_max = clone $query;
  $query_max_result = $query_max->condition($nr_alias . '.rating', 10)
    ->range(0, $count)
    ->execute();
  foreach ($query_max_result as $record) {
    $return[$record->nid] = node_load($record->nid);
  }
  $count -= $query_max->countQuery()->execute()->fetchField();

  // If there's room for more, look for nodes with less than max rating.
  if ($count > 0) {
    $query_less = clone $query;
    $query_less->condition($nr_alias . '.rating', 10, '<');
    // Only pick random if there's more nodes than we need.
    if ($query_less->countQuery()->execute()->fetchField() > $count) {
      $query_less_result = $query_less->execute();

      // Build array to randomly pick nodes from.
      $nodes = array();
      foreach ($query_less_result as $record) {
        $rating = $record->rating;
        for ($i = 0; $i < $rating; $i++) {
          $nodes[] = $record->nid;
        }
      }

      while ($count-- > 0) {
        $random_key = array_rand($nodes);
        $nid = $nodes[$random_key];
        $return[$nid] = node_load($nid);
        // Remove the node completely from the array.
        $nodes = array_diff_key($nodes, array_flip(array_keys($nodes, $nid)));
      }
    }
    // Else include all nodes.
    else {
      // Todo move above if statement.
      $query_less_result = $query_less->execute();
      foreach ($query_less_result as $record) {
        $return[$record->nid] = node_load($record->nid);
      }
    }
  }

  return $return;
}

/**
 * Implements hook_node_delete().
 *
 * When a node is deleted, ensure that any associated ratings is deleted from
 * the database.
 */
function ting_search_context_node_delete($node) {
  ting_search_context_unrate_node($node->nid);
}

/**
 * Unrates a node by completely deleting all accosiated ratings.
 *
 * @param int $nid
 *   The ID of the node to unrate.
 *
 * @return int
 *   The number of deleted rows in the nodes_rated table.
 */
function ting_search_context_unrate_node($nid) {
  return db_delete('ting_search_context_nodes_rated')
    ->condition('nid', $nid)
    ->execute();
}

/**
 * Saves a node rating in the database.
 *
 * @param int $context_id
 *   The ID of the context to rate in.
 * @param int $nid
 *   The ID of node to rate.
 * @param int $rating
 *   The number of the rating (E.g. 1 - 10).
 *
 * @return undefined
 *   (https://www.drupal.org/node/310079)
 */
function ting_search_context_rate_node($context_id, $nid, $rating) {
  // Merge query ensures that nodes isn't rated in the same context twice.
  return db_merge('ting_search_context_nodes_rated')
    ->key(array(
      'context_id' => $context_id,
      'nid' => $nid,
    ))
    ->fields(array(
      'rating' => $rating,
    ))
    ->execute();
}

/**
 * Checks search string context.
 *
 * Checks to see if a search string context with an identical $search_string
 * already exists in the database.
 *
 * @param string $search_string
 *   The search string to check for.
 *
 * @return mixed
 *   A context object if an identical search string context was found.
 *   FALSE otherwise.
 */
function ting_search_context_search_string_context_exists($search_string) {
  $search_string = mb_strtolower($search_string, 'UTF-8');

  // We can't be sure that the DB's string manipulation is compatible with PHP's
  // so we load all search string contexts and compare in code.
  $search_string_contexts = ting_search_context_get_all_contexts('search');

  foreach ($search_string_contexts as $search_string_context) {
    if ($search_string === mb_strtolower($search_string_context->search, 'UTF-8')) {
      return $search_string_context;
    }
  }
  return FALSE;
}

/**
 * Checks to see if an identical subject context already exists.
 *
 * @param array $subjects
 *   The subjects the search for. The order doesn't matter.
 */
function ting_search_context_subject_context_exists(array $subjects) {
  $subject_contexts = ting_search_context_get_all_contexts('subject');

  foreach ($subject_contexts as $subject_context) {
    $db_subjects = explode(', ', $subject_context->subjects);
    // Since we make sure the user can't create contexts with duplicate subjects
    // it's easy to check for identical contexts. If this wasn't the case, we
    // would have to take a more advanced appproach:
    // http://stackoverflow.com/questions/4519847/comparing-arrays-in-php-without-caring-for-the-order
    if (count($db_subjects) == count($subjects) && array_diff($db_subjects, $subjects) == array()) {
      return $subject_context;
    }
  }
  return FALSE;
}

/**
 * Deletes ratings associatied with one or more contexts.
 *
 * @param mixed $context_ids
 *   A string containing a single context_id or an array of context_ids.
 */
function ting_search_context_ratings_delete($context_ids) {
  return db_delete('ting_search_context_nodes_rated')
    ->condition('context_id', $context_ids)
    ->execute();
}

/**
 * Ratings loader.
 *
 * @param mixed $context_ids
 *   A string containing a single context_id or an array of context_ids.
 * @param mixed $nids
 *   A string containing a single nid or an array of nids.
 *
 * @return mixed $ratings
 *   An array of ratings keyed by nids if $context_ids was set or by context_ids
 *   if $nids was set (and $context_ids not).
 *   A result set with all ratings if no parameter was set.
 */
function ting_search_context_ratings_load($context_ids = NULL, $nids = NULL) {
  $query = db_select('ting_search_context_nodes_rated', 'nr')->fields('nr');

  if (isset($context_ids)) {
    $query->condition('context_id', $context_ids);
    // All ratings for a context. key by nid.
    if (is_int($context_ids)) {
      return $query->execute()->fetchAllAssoc('nid');
    }
  }
  if (isset($nids)) {
    $query->condition('nid', $nids);
    // All ratings for a node. key by context_id.
    if (is_int($nids)) {
      return $query->execute()->fetchAllAssoc('context_id');
    }
  }

  return $query->execute();
}


/**
 * Saves or updates a context.
 *
 * @param object $context
 *   The context-object to be saved.
 *   If $context->context_id is omitted a new context will be saved in the db.
 *
 * @return mixed
 *   FALSE if the insert or updated failed.
 *   Otherwise SAVED_NEW or SAVED_UPDATED depending on the operation performed.
 *
 * @see ting_search_context_schema()
 * @see ting_search_context_load()
 * @see ting_search_context_load_multiple()
 */
function ting_search_context_save($context) {
  try {
    // Determine if this is a new or an existing context.
    $id = empty($context->context_id) ? array() : 'context_id';

    return drupal_write_record('ting_search_context_contexts', $context, $id);
  }
  catch (Exception $e) {
    watchdog_exception('ting_search_context', $e);
    return FALSE;
  }
}

/**
 * Deletes a context and any associated ratings.
 *
 * @param int $context_id
 *   The ID of the context to delete.
 *
 * @return mixed
 *   TRUE if deletion was successful.
 *   FALSE if something went wrong or nothing was deleted.
 */
function ting_search_context_delete($context_id) {
  return ting_search_context_delete_multiple(array($context_id));
}

/**
 * Deletes multiple contexts and any associated ratings.
 *
 * @param array $context_ids
 *   And array with ids of the contexts to delete.
 *
 * @return mixed
 *   int. The number of contexts deleted.
 *   False if something went wrong or nothing was deleted.
 */
function ting_search_context_delete_multiple(array $context_ids) {
  // We're also deleting associated ratings, so use a transaction.
  $transaction = db_transaction();

  $result = FALSE;
  if (!empty($context_ids)) {
    try {
      // Delete associated ratings. They're useless when serial ID is removed.
      $result_ratings = ting_search_context_ratings_delete($context_ids);

      // Delete the contexts.
      $result = db_delete('ting_search_context_contexts')
        ->condition('context_id', $context_ids, 'IN')
        ->execute();

      if ($result) {
        // Reset the load_multiple static cache.
        drupal_static_reset('ting_search_context_load_multiple');
      }
    }
    catch (Exception $e) {
      $transaction->rollback();
      watchdog_exception('ting_search_context', $e);
    }
  }

  return $result;
}

/**
 * Loads a single context from the database.
 *
 * @param int $context_id
 *   The ID of context to fetch.
 * @param bool $reset
 *   Whether to reset the internal context cache.
 */
function ting_search_context_load($context_id = NULL, $reset = FALSE) {
  $context_ids = isset($context_id) ? array($context_id) : array();
  $context = ting_search_context_load_multiple($context_ids, $reset);
  return reset($context);
}

/**
 * Loads multiple contexts from the database.
 *
 * @param array $context_ids
 *   An array of Context IDs.
 * @param bool $reset
 *   Whether to reset the internal context cache.
 *
 * @return array
 *   An array of context objects keyed by context_id.
 *   Empty array if nothing was found.
 */
function ting_search_context_load_multiple($context_ids = array(), $reset = FALSE) {
  // First consult the static cache.
  $cached_contexts = &drupal_static(__FUNCTION__);

  // Ensure $cached_contexts is initialized as array
  // Initialize array if a cache reset was requested.
  if (!isset($cached_contexts) || $reset) {
    $cached_contexts = array();
  }

  // Determine if we have to query the datatbase.
  $missing = array_diff($context_ids, array_keys($cached_contexts));

  // Get the contexts that wasn't found in the static cache.
  if (!empty($missing)) {
    $cached_contexts += db_select('ting_search_context_contexts', 'tsc')
      ->fields('tsc')
      ->condition('tsc.context_id', $missing, 'IN')
      ->execute()->fetchAllAssoc('context_id');
  }

  return array_intersect_key($cached_contexts, array_flip($context_ids));
}

/**
 * Get all contexts.
 *
 * Get all contexts in the system or all contexts of a specific type if the
 * $type parameter is supplied.
 *
 * @param string $type
 *   Constrain the returned contexts to a specific type. (optional).
 *
 * @return array
 *   Array representing the context.
 *   Empty array if nothing was found.
 *
 * @see ting_search_context_schema()
 */
function ting_search_context_get_all_contexts($type = NULL) {
  $query = db_select('ting_search_context_contexts', 'tsc')
    ->fields('tsc');

  if (isset($type)) {
    $query->condition('tsc.type', $type);
  }

  return $query->execute()->fetchAll();
}

/**
 * Defines the positions for placing the related content on the search page.
 *
 * @return array
 *   Indexed by position name.
 */
function ting_search_context_get_positions() {
  return array(
    'js-below-search-result' => t('Below search result'),
    'js-below-facets' => t('Below facets'),
    'js-above-search-result' => t('Above search result'),
  );
}

/**
 * Defines the context types we support.
 */
function ting_search_context_get_types() {
  return array(
    'system' => t('System context'),
    'subject' => t('Subject context'),
    'search' => t('Search string context'),
  );
}

/**
 * Implements hook_image_default_styles().
 */
function ting_search_context_image_default_styles() {
  return array(
    'ting_search_context' => array(
      'name' => 'ting_search_context',
      'effects' => array(
        array(
          'label' => 'Scale and crop',
          'effect callback' => 'image_scale_and_crop_effect',
          'dimensions callback' => 'image_resize_dimensions',
          'module' => 'image',
          'name' => 'image_scale_and_crop',
          'data' => array(
            'width' => '540',
            'height' => '405',
          ),
          'weight' => '1',
        ),
      ),
    ),
    'ting_search_context_thumbnail' => array(
      'name' => 'ting_search_context',
      'effects' => array(
        array(
          'label' => 'Scale and crop',
          'effect callback' => 'image_scale_and_crop_effect',
          'dimensions callback' => 'image_resize_dimensions',
          'module' => 'image',
          'name' => 'image_scale_and_crop',
          'data' => array(
            // The same ratio as the one used in frontend.
            'width' => '108',
            'height' => '81',
          ),
          'weight' => '1',
        ),
      ),
    ),
  );
}

/**
 * Wrapper function that adds the modules JavaScript.
 */
function _ting_search_context_add_javascript() {
  $path = drupal_get_path('module', 'ting_search_context');
  drupal_add_library('system', 'ui.widget');
  drupal_add_js($path . '/js/jquery.rs.carousel.js');
  drupal_add_js($path . '/js/ting_search_context.js');
}

/**
 * Wrapper function that adds the modules css.
 */
function _ting_search_context_add_css() {
  $path = drupal_get_path('module', 'ting_search_context');
  drupal_add_css($path . '/css/ting_search_context.base.css');
}