<?php

/**
 * Implements hook_entity_info().
 */
function variable_entity_entity_info() {
  return array(
    'variable_entity' => array(
      'label' => t('Variable entity'),
      'uri callback' => 'variable_entity_uri',
      'controller class' => 'VariableEntityController',
      'entity keys' => array(
        'id' => 'id',
        'label' => 'label',
      ),
      'fieldable' => TRUE,
      'bundles' => array(
        'variable_entity' => array(
          'label' => t('Variable entity'),
          'admin' => array(
            'path' => 'variable-entity',
            'access arguments' => array('administer content types'),
          ),
        ),
      ),
    ),
  );
}

/**
 * Implements hook_menu().
 */
function variable_entity_menu() {
  return array(
    'variable-entity' => array(
      'title' => 'Variable Entities',
      'page callback' => 'variable_entity_admin_page',
      'file' => 'variable_entity_pages.inc',
      'access callback' => TRUE,
    ),
    'variable-entity/manage' => array(
      'title' => 'Manage',
      'type' => MENU_DEFAULT_LOCAL_TASK,
    ),
    'variable-entity/view/%variable_entity' => array(
      'page callback' => 'variable_entity_view',
      'page arguments' => array(2),
      'title callback' => 'entity_label',
      'title arguments' => array('variable_entity', 2),
      'file' => 'variable_entity_pages.inc',
      'access callback' => TRUE,
    ),
  );
}

/**
 * Menu argument loader callback.
 */
function variable_entity_load($id) {
  $return = entity_load('variable_entity', array($id));
  return isset($return[$id]) ? $return[$id] : FALSE;
}

/**
 * Entity URI callback.
 */
function variable_entity_uri($variable_entity) {
  return array('path' => 'variable-entity/view/' . $variable_entity->id);
}

/**
 * The controller class. Inherits from DrupalDefaultEntityController, but overrides the load() method,
 * so the database never gets used.
 */
class VariableEntityController extends DrupalDefaultEntityController {
  // ids have to be numeric, so we need an array mapping ids to variable names that we know about. store it in a variable.
  public $variables = array();

  public function __construct($type = 'variable_entity') {
    parent::__construct($type);
    $this->variables = variable_get('variable_entity', array('site_name', 'site_mail', 'theme_default'));
  }

  public function resetCache(array $ids = NULL) { }

  public function load($ids = array(), $conditions = array()) {
    $entities = array();
    foreach($ids as $id) {
      if(isset($this->variables[$id])) {
        $ent = new stdClass();
        $ent->variable_name = $this->variables[$id];
        $ent->variable = variable_get($this->variables[$id], new stdClass());
        $ent->label = t('Entity @id contains @var variable', array('@id' => $id, '@var' => $this->variables[$id]));
        $ent->id = $id;
        $entities[$id] = $ent;
      }
    }

    // add fields
    if(!empty($entities)) {
      $this->attachLoad($entities, array());
    }

    return $entities;
  }
}