<?php

/**
 * Implements hook_services_resources_alter().
 *
 * Alter all resources that support UUIDs, to make use this functionality when
 * exposing them through Services.
 *
 * Since we are working with UUID enabled entities, the 'create' method is
 * redundant. Instead, clients should do a PUT to '<entity_type>/<uuid>'. This
 * will route through the 'update' method and create the entity if it doesn't
 * exist. This is the most logical thing to do, since it's up to the client to
 * generate and set the UUID on the entity.
 */
function uuid_services_services_resources_alter(&$resources, &$endpoint) {
  foreach (entity_get_info() as $entity_type => $entity_info) {
    if (isset($entity_info['uuid']) && $entity_info['uuid'] == TRUE && isset($resources[$entity_type])) {
      unset($resources[$entity_type]['operations']['create']);

      // Alter 'retrieve' method to use UUID enabled functions and arguments.
      $resources[$entity_type]['operations']['retrieve']['help'] = t('Retrieve %label entities based on UUID.', array('%label' => $entity_info['label']));
      $resources[$entity_type]['operations']['retrieve']['callback'] = '_uuid_services_entity_retrieve';
      $resources[$entity_type]['operations']['retrieve']['access callback'] = '_uuid_services_entity_access';
      $resources[$entity_type]['operations']['retrieve']['access arguments'] = array('view');
      $resources[$entity_type]['operations']['retrieve']['access arguments append'] = TRUE;
      $resources[$entity_type]['operations']['retrieve']['args'] = array(
        // This argument isn't exposed in the service, only used internally..
        array(
          'name' => 'entity_type',
          'description' => t('The entity type.'),
          'type' => 'string',
          'default value' => $entity_type,
          'optional' => TRUE,
        ),
        array(
          'name' => 'uuid',
          'description' => t('The %label UUID.', array('%label' => $entity_info['label'])),
          'type' => 'text',
          'source' => array('path' => 0),
        ),
      );

      // Alter 'update' method to use UUID enabled functions and arguments.
      $resources[$entity_type]['operations']['update']['help'] = t('Update or create %label entities based on UUID. The payload must be formatted according to the <a href="!url">OData protocol</a>.', array('%label' => $entity_info['label'], '!url' => 'http://www.odata.org/developers/protocols'));
      $resources[$entity_type]['operations']['update']['callback'] = '_uuid_services_entity_update';
      $resources[$entity_type]['operations']['update']['access callback'] = '_uuid_services_entity_access';
      $resources[$entity_type]['operations']['update']['access arguments'] = array('update');
      $resources[$entity_type]['operations']['update']['access arguments append'] = TRUE;
      $resources[$entity_type]['operations']['update']['args'] = array(
        // This argument isn't exposed in the service, only used internally..
        array(
          'name' => 'entity_type',
          'description' => t('The entity type.'),
          'type' => 'string',
          'default value' => $entity_type,
          'optional' => TRUE,
        ),
        array(
          'name' => 'uuid',
          'description' => t('The %label UUID.', array('%label' => $entity_info['label'])),
          'type' => 'text',
          'source' => array('path' => 0),
        ),
        array(
          'name' => 'entity',
          'description' => t('The %label entity object.', array('%label' => $entity_info['label'])),
          'type' => 'struct',
          'source' => 'data',
        ),
      );

      // Alter 'delete' method to use UUID enabled functions and arguments.
      $resources[$entity_type]['operations']['delete']['help'] = t('Delete %label entities based on UUID.', array('%label' => $entity_info['label']));
      $resources[$entity_type]['operations']['delete']['callback'] = '_uuid_services_entity_delete';
      $resources[$entity_type]['operations']['delete']['access callback'] = '_uuid_services_entity_access';
      $resources[$entity_type]['operations']['delete']['access arguments'] = array('delete');
      $resources[$entity_type]['operations']['delete']['access arguments append'] = TRUE;
      $resources[$entity_type]['operations']['delete']['args'] = array(
        // This argument isn't exposed in the service, only used internally..
        array(
          'name' => 'entity_type',
          'description' => t('The entity type.'),
          'type' => 'string',
          'default value' => $entity_type,
          'optional' => TRUE,
        ),
        array(
          'name' => 'uuid',
          'description' => t('The %label UUID.', array('%label' => $entity_info['label'])),
          'type' => 'text',
          'source' => array('path' => 0),
        ),
      );
    }
  }
}

/**
 * Callback for the 'retrieve' method.
 *
 * @see entity_uuid_load()
 */
function _uuid_services_entity_retrieve($entity_type, $uuid) {
  try {
    $entities = entity_uuid_load($entity_type, array($uuid));
    $entity = reset($entities);
    return $entity;
  }
  catch (Exception $exception) {
    watchdog_exception('uuid_services', $exception);
    return services_error($exception, 406, $uuid);
  }
}

/**
 * Callback for the 'update' method.
 *
 * @see entity_uuid_save()
 */
function _uuid_services_entity_update($entity_type, $uuid, $entity) {
  try {
    $controller = entity_get_controller($entity_type);
    if ($controller instanceof EntityAPIControllerInterface) {
      $entity = $controller->create($entity);
    }
    else {
      $entity = (object) $entity;
    }
    entity_uuid_save($entity_type, $entity);
    return $entity;
  }
  catch (Exception $exception) {
    watchdog_exception('uuid_services', $exception);
    return services_error($exception, 406, $entity);
  }
}

/**
 * Callback for the 'delete' method.
 *
 * @see entity_uuid_delete()
 */
function _uuid_services_entity_delete($entity_type, $uuid) {
  try {
    $return = entity_uuid_delete($entity_type, array($uuid));
    return $return;
  }
  catch (Exception $exception) {
    watchdog_exception('uuid_services', $exception);
    return services_error($exception, 406, $uuid);
  }
}

/**
 * Access callback.
 *
 * @param $op
 *   The operation we are trying to do on the entity. Can only be:
 *   - "view"
 *   - "update"
 *   - "delete"
 *   See 'uuid_services_services_resources_alter()' for an explanation why
 *   'create' is missing.
 * @param $args
 *   The arguments passed to the method. The keys are holding the following:
 *   0. <entity_type>
 *   1. <uuid>
 *   2. <entity> (only available if $op == 'update')
 */
function _uuid_services_entity_access($op, $args) {
  try {
    // Fetch the information we have to work with.
    $entity_type = $args[0];
    // Load functions always deal with multiple entities. So does this lookup
    // function. But in practice this will always only be one id.
    $entity_ids = entity_get_id_by_uuid($entity_type, array($args[1]));
    $entity = NULL;
    if (!empty($args[2])) {
      $entity = entity_create($entity_type, $args[2]);
      // We have to make the entity local (i.e. only have local references), for
      // access functions to work on it.
      entity_make_entity_local($entity_type, $entity);
    }
    // Fetch the local entity if we've got an id.
    elseif (!empty($entity_ids)) {
      $entities = entity_load($entity_type, $entity_ids);
      $entity = reset($entities);
    }

    // If we've been routed to the 'update' method and the entity we are
    // operating on doesn't exist yet, that should be reflected.
    if ($op == 'update' && empty($entity_ids)) {
      $op = 'create';
    }
    // Taxonomy and Comment module uses 'edit' instead of 'update'.
    // Oh, how I love Drupal consistency.
    if (($entity_type == 'taxonomy_term' || $entity_type == 'comment') && $op == 'update') {
      $op = 'edit';
    }
    // The following code is taken from entity_access() with some extra logic
    // to handle the case where an entity type is not defining an access
    // callback. With this logic, it's important that all entity types that
    // needs access control have an access callback defined.
    if (($info = entity_get_info()) && isset($info[$entity_type]['access callback'])) {
      return $info[$entity_type]['access callback']($op, $entity, NULL, $entity_type);
    }
    return TRUE;
  }
  catch (Exception $exception) {
    watchdog_exception('uuid_services', $exception);
    return services_error($exception, 406, $entity_type);
  }
}

/**
 * Implements hook_services_resources().
 */
function uuid_services_services_resources() {
  module_load_include('inc', 'uuid_services', 'resources/field_collection.resource');

  $resources = array(
    '#api_version' => 3002,
  );

  $resources += _field_collection_resource_definition();

  return $resources;
}
