<?php

/**
 * @file
 * Feeds mapping implementation for the Entity reference module
 */

/**
 * Implements hook_feeds_processor_targets_alter().
 *
 * @see FeedsNodeProcessor::getMappingTargets().
 */
function entityreference_feeds_processor_targets_alter(&$targets, $entity_type, $bundle_name) {

  foreach (field_info_instances($entity_type, $bundle_name) as $name => $instance) {
    $info = field_info_field($name);
    if ($info['type'] == 'entityreference') {
      $targets[$name] = array(
        'name'        => check_plain($instance['label']),
        'callback'    => 'entityreference_feeds_set_target',
        'description' => t('The field instance @label of @id', array(
          '@label' => $instance['label'],
          '@id'    => $name,
        )),
      );
    }
  }
}

/**
 * Entity reference callback for mapping.
 *
 * When the callback is invoked, $target contains the name of the field the
 * user has decided to map to and $value contains the value of the feed item
 * element the user has picked as a source.
 *
 * @param $source
 *   A FeedsSource object.
 * @param $entity
 *   The entity to map to.
 * @param $target
 *   The target key on $entity to map to.
 * @param $value
 *   The value to map. MUST be an array.
 * @param $mapping
 *   Array of mapping settings for current value.
 * @param $input_format
 *   TRUE if an input format should be applied.
 */
function entityreference_feeds_set_target($source, $entity, $target, $value, $mapping, $input_format = FALSE) {

  // Don't do anything if we weren't given any data.
  if (empty($value)) {
    return;
  }

  // Assume that the passed in value could really be any number of values.
  if (is_array($value)) {
    $values = $value;
  }
  else {
    $values = array($value);
  }

  // Get some useful field information.
  $info = field_info_field($target);

  // Set the language of the field depending on the mapping.
  $language = isset($mapping['language']) ? $mapping['language'] : LANGUAGE_NONE;

  // Iterate over all values.
  $iterator = 0;
  $field = isset($entity->$target) ? $entity->$target : array();
  foreach ($values as $value) {

    // Only process if this value was set for this instance.
    if ($value) {

      // Fetch the entity ID resulting from the mapping table look-up.
      $entity_id = db_query(
        'SELECT entity_id FROM {feeds_item} WHERE guid = :guid',
        array(':guid' => $value)
      )->fetchField();

      /*
       * Only add a reference to an existing entity ID if there exists a
       * mapping between it and the provided GUID.  In cases where no such
       * mapping exists (yet), don't do anything here.  There may be a mapping
       * defined later in the CSV file.  If so, and the user re-runs the import
       * (as a second pass), we can add this reference then.  (The "Update
       * existing nodes" option must be selected during the second pass.)
       */
      if ($entity_id) {

        // Assign the target ID.
        $field[$language][$iterator]['target_id']   = $entity_id;
      }
      else /* there is no $entity_id, no mapping */ {

        /*
         * Feeds stores a hash of every line imported from CSVs in order to
         * make the import process more efficient by ignoring lines it's
         * already seen.  We need to short-circuit this process in this case
         * because users may want to re-import the same line as an update later
         * when (and if) a map to a reference exists.  So in order to provide
         * this opportunity later, we need to destroy the hash.
         */
        unset($entity->feeds_item->hash);
      }
    }

    // Break out of the loop if this field is single-valued.
    if ($info['cardinality'] == 1) {
      break;
    }
    $iterator++;
  }

  // Add the field to the entity definition.
  $entity->{$target} = $field;
}