<?php

/**
 * @file
 * Hooks provided by the diff module.
 */

/**
 * @addtogroup hooks
 * @{
 */

/**
 * Allow modules to provide a comparison about entities.
 *
 * @param object $old_entity
 *   The older entity revision.
 * @param object $new_entity
 *   The newer entity revision.
 * @param array $context
 *   An associative array containing:
 *   - entity_type: The entity type; e.g., 'node' or 'user'.
 *   - view_mode: The view mode to use. Defaults to FALSE.
 *
 * @return array
 *   An associative array of values keyed by the entity property.
 *
 * @todo
 *   Investiagate options and document these.
 */
function hook_entity_diff($old_entity, $new_entity, $context) {
  if ($context['entity_type'] == 'node') {
    $type = node_type_get_type($new_entity);
    $result['title'] = array(
      '#name' => $type->title_label,
      '#old' => array($old_entity->title),
      '#new' => array($new_entity->title),
      '#weight' => -5,
      '#settings' => array(
        'show_header' => FALSE,
      ),
    );
  }
}

/**
 * Allow modules to alter a comparison about entities.
 *
 * @param array $entity_diffs
 *   An array of entity differences.
 * @param array $context
 *   An associative array containing:
 *   - entity_type: The entity type; e.g., 'node' or 'user'.
 *   - old_entity: The older entity.
 *   - new_entity: The newer entity.
 *   - view_mode: The view mode to use. Defaults to FALSE.
 *
 * @see hook_entity_diff()
 */
function hook_entity_diff_alter($entity_diffs, $context) {
}

/**
 * Callback to the module that defined the field to prepare items comparison.
 *
 * This allows the module to alter all items prior to rendering the comparative
 * values. It is mainly used to bulk load entities to reduce overheads
 * associated with loading entities individually.
 *
 * @param array $old_items
 *   An array of field items from the older revision.
 * @param array $new_items
 *   An array of field items from the newer revision.
 * @param array $context
 *   An associative array containing:
 *   - entity_type: The entity type; e.g., 'node' or 'user'.
 *   - bundle: The bundle name.
 *   - field: The field that the items belong to.
 *   - instance: The instance that the items belong to.
 *   - language: The language associated with $items.
 *   - old_entity: The older entity.
 *   - new_entity: The newer entity.
 *
 * @see MODULE_field_diff_view()
 */
function MODULE_field_diff_view_prepare(&$old_items, &$new_items, $context) {
  $fids = array();
  foreach (array_merge_recursive($old_items, $new_items) as $info) {
    $fids[$info['fid']] = $info['fid'];
  }
  // A single load is much faster than individual loads.
  $files = file_load_multiple($fids);

  // For ease of processing, store a reference of the entity on the item array.
  foreach ($old_items as $delta => $info) {
    $old_items[$delta]['file'] = isset($files[$info['fid']]) ? $files[$info['fid']] : NULL;
  }
  foreach ($new_items as $delta => $info) {
    $new_items[$delta]['file'] = isset($files[$info['fid']]) ? $files[$info['fid']] : NULL;
  }
}

/**
 * Callback to the module that defined the field to generate items comparisons.
 *
 * @param array $items
 *   An array of field items from the entity.
 * @param array $context
 *   An associative array containing:
 *   - entity: The entity being compared.
 *   - entity_type: The entity type; e.g., 'node' or 'user'.
 *   - bundle: The bundle name.
 *   - field: The field that the items belong to.
 *   - instance: The instance that the items belong to.
 *   - language: The language associated with $items.
 *   - old_entity: The older entity.
 *   - new_entity: The newer entity.
 *
 * @see MODULE_field_diff_view_prepare()
 */
function MODULE_field_diff_view($items, $context) {
  $diff_items = array();
  foreach ($items as $delta => $item) {
    if (isset($item['file'])) {
      $diff_items[$delta] = $item['file']->filename . ' [fid: ' . $item['fid'] . ']';
    }
  }

  return $diff_items;
}

/**
 * Allow other modules to interact with MODULE_field_diff_view_prepare().
 *
 * @param array $old_items
 *   An array of field items from the older revision.
 * @param array $new_items
 *   An array of field items from the newer revision.
 * @param array $context
 *   An associative array containing:
 *   - entity_type: The entity type; e.g., 'node' or 'user'.
 *   - bundle: The bundle name.
 *   - field: The field that the items belong to.
 *   - instance: The instance that the items belong to.
 *   - language: The language associated with $items.
 *   - old_entity: The older entity.
 *   - new_entity: The newer entity.
 *
 * @see MODULE_field_diff_view_prepare()
 */
function hook_field_diff_view_prepare_alter($old_items, $new_items, $context) {

}

/**
 * Allow other modules to interact with MODULE_field_diff_view().
 *
 * @param array $values
 *   An array of field items from the entity ready for comparison.
 * @param array $items
 *   An array of field items from the entity.
 * @param array $context
 *   An associative array containing:
 *   - entity: The entity being compared.
 *   - entity_type: The entity type; e.g., 'node' or 'user'.
 *   - bundle: The bundle name.
 *   - field: The field that the items belong to.
 *   - instance: The instance that the items belong to.
 *   - language: The language associated with $items.
 *   - old_entity: The older entity.
 *   - new_entity: The newer entity.
 *
 * @see MODULE_field_diff_view()
 */
function hook_field_diff_view_alter($values, $items, $context) {

}

/**
 * @} End of "addtogroup hooks".
 */