<?php

/**
 * @file
 * Main module file.
 */

/**
 * Implements hook_menu().
 */
function cer_menu() {
  $items = array();

  $items['admin/config/system/cer'] = array(
    'title' => 'Corresponding entity references',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('cer_settings_form'),
    'access arguments' => array('administer cer settings'),
    'file' => 'cer.admin.inc',
    'type' => MENU_NORMAL_ITEM,
  );
  $items['admin/config/system/cer/references'] = array(
    'title' => 'References',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('cer_settings_form'),
    'access arguments' => array('administer cer settings'),
    'file' => 'cer.admin.inc',
    'type' => MENU_DEFAULT_LOCAL_TASK,
  );
  $items['admin/config/system/cer/update'] = array(
    'title' => 'Update existing entities',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('cer_update_form'),
    'access arguments' => array('administer cer settings'),
    'file' => 'cer.admin.inc',
    'type' => MENU_LOCAL_TASK,
  );

  return $items;
}

/**
 * Implements hook_permission().
 */
function cer_permission() {
  return array(
    'administer cer settings' => array(
      'title' => t('Administer corresponding entity reference settings'),
    )
  );
}

/**
 * Implements hook_help().
 */
function cer_help($path, $arg) {
  $output = '';
  if ($path == 'admin/config/system/cer') {
    $output .= t('Check which entity references should listen to each other. When checking a check box a reference on entity type A to entity B will automatically update the entity reference field on entity B adding an entry which points to entity A.');
  }
  elseif ($path == 'admin/config/system/cer/update') {
    $output .= t('This will update all the existing entities for the selected content types so that their entity reference fields are in sync.');
    $output .= '<br />';
    $output .= t('This process may take a long time depending on the number of entities you are updating.');
    $output .= '<br /><br />';
    $output .= t('When the process is finished you will see a count of the number of entities that were updated.');
  }
  return $output;
}

/**
 * Implements hook_field_delete_instance().
 */
function cer_field_delete_instance($instance) {
  foreach (cer_preset_load_enabled() as $row) {
    $keys = explode('*', $row->entity_types_content_fields);

    if (($keys[0] == $instance['entity_type'] && $keys[1] == $instance['bundle'] && $keys[2] == $instance['field_name']) || ($keys[3] == $instance['entity_type'] && $keys[4] == $instance['bundle'] && $keys[5] == $instance['field_name'])) {
      cer_preset_delete($row->entity_types_content_fields);
    }
  }
}

/**
 * Implements hook_field_delete_field().
 */
function cer_field_delete_field($field) {
  foreach (cer_preset_load_enabled() as $row) {
    $keys = explode('*', $row->entity_types_content_fields);

    if ($keys[2] == $field['field_name'] || $keys[5] == $field['field_name']) {
      cer_preset_delete($row->entity_types_content_fields);
    }
  }
}

/**
 * Implements hook_theme().
 */
function cer_theme() {
  return array(
    'cer_label' => array(
      'variables' => array('key' => ''),
    ),
  );
}

function theme_cer_label($variables) {
  $key = explode(' ', $variables['key']);
  
  $local = field_info_instance($key[0], $key[2], $key[1]);
  $remote = field_info_instance($key[3], $key[5], $key[4]);

  $message = 'Correspond <span title="!local_field">%local_label</span> on !local_entity(s) of type %local_bundle with <span title="!remote_field">%remote_label</span> on !remote_entity(s) of type %remote_bundle.';

  $variables = array(
    '%local_label' => $local['label'],
    '!local_field' => $local['field_name'],
    '!local_entity' => $local['entity_type'],
    '%local_bundle' => $local['bundle'],
    '%remote_label' => $remote['label'],
    '!remote_field' => $remote['field_name'],
    '!remote_entity' => $remote['entity_type'],
    '%remote_bundle' => $remote['bundle'],
  );

  return t($message, $variables);
}

/**
 * Implements hook_entity_insert().
 */
function cer_entity_insert($entity, $type) {
  cer_processing_entity('insert', $entity, $type);
}

/**
 * Implements hook_entity_update().
 */
function cer_entity_update($entity, $type) {
  cer_processing_entity('update', $entity, $type);
}

/**
 * Implements hook_entity_delete().
 */
function cer_entity_delete($entity, $type) {
  cer_processing_entity('delete', $entity, $type);
}

/**
 * Load enabled CER presets.
 */
function cer_preset_load_enabled() {
  ctools_include('export');
  return ctools_export_load_object('cer', 'conditions', array('enabled' => 1));
}

/**
 * Return CER preset by key.
 */
function cer_preset_load($key) {
  ctools_include('export');
  return ctools_export_crud_load('cer', $key);
}

/**
 * Return 1 if CER preset specified by given key is enabled.
 */
function cer_preset_enabled($key) {
  $preset = cer_preset_load($key);
  return empty($preset) ? 0 : $preset->enabled;
}

/**
 * Deletes or disables a given CER preset.
 */
function cer_preset_delete($key) {
  ctools_include('export');

  ctools_export_crud_delete('cer', $key);
  ctools_export_crud_disable('cer', $key);

  ctools_export_load_object_reset('cer');
}

/**
 * Process a entity's corresponding entity references.
 *
 * @param string $op 
 *  The operation being performed on the entity (insert, update, or delete).
 *
 * @param object $entity
 *  The entity.
 *
 * @param string $entity_type
 *  The entity type.
 *
 * @param array $context
 *  Either the Batch API context (since this is the callback function used
 *  during bulk update) or NULL if we're not in a batch job.
 */
function cer_processing_entity($op, $entity, $entity_type, &$context = NULL) {
  // If the entity is of the wrong type, entity_extract_IDs() will throw
  // EntityMalformedException and rightfully bail out here.
  list (, , $bundle) = entity_extract_IDs($entity_type, $entity);

  $result = cer_preset_load_enabled();

  foreach ($result as $row) {
    $keys = explode('*', $row->entity_types_content_fields);

    if ($keys[0] == $entity_type && $keys[1] == $bundle) {
      try {
        $handler = new CerHandler($row->entity_types_content_fields, $entity);
        call_user_func(array($handler, $op));
      }
      catch (CerException $e) {
        if (isset($context)) {
          $context['results']['errors'][] = $e;
        }
        else {
          throw $e;
        }
      }
    }

    if ($keys[3] == $entity_type && $keys[4] == $bundle) {
      $preset = implode('*', array($keys[3], $keys[4], $keys[5], $keys[0], $keys[1], $keys[2]));

      try {
        $handler = new CerHandler($preset, $entity);
        call_user_func(array($handler, $op));
      }
      catch (CerException $e) {
        if (isset($context)) {
          $context['results']['errors'][] = $e;
        }
        else {
          throw $e;
        }
      }
    }
  }

  if (isset($context)) {
    $context['results']['count']++;
  }
}

/**
 * Batch 'finished' callback.
 */
function cer_batch_update_existing_finished($success, $results, $operations) {
  if ($success) {
    $message = format_plural($results['count'], '1 entity processed.', '@count entities processed.');

    if (isset($results['errors'])) {
      $type = 'warning';
      foreach ($results['errors'] as $e) {
        drupal_set_message($e->getMessage(), 'error');
      }
    }
    else {
      $type = 'status';
    }
    drupal_set_message($message, $type);
  }
  else {
    // An error occurred. $operations contains the operations that remained unprocessed.
    $error_operation = reset($operations);
    $message = 'An error occurred while processing ' . $error_operation[0] . ' with arguments:' . print_r($error_operation[0], TRUE);
    drupal_set_message($message, 'error');
  }
}

/**
 * Implements hook_ctools_plugin_api().
 */
function cer_ctools_plugin_api($owner, $api) {
  if ($owner == 'cer' && $api == 'default_cer_presets') {
    return array('version' => 1);
  }
}

/**
 * Update field data.
 *
 * @param $node the referenced node to be updated.
 */
function _cer_update($entity_type, $entity) {
  $entity->original = isset($entity->original) ? $entity->original : NULL;

  field_attach_presave($entity_type, $entity);
  field_attach_update($entity_type, $entity);

  $extract_ids = entity_extract_IDs($entity_type, $entity);
  $id = array_shift($extract_ids);
  entity_get_controller($entity_type)->resetCache(array($id));
}