<?php

/**
 * @file
 * Install file for the entity API.
 */

/**
 * Implements hook_enable().
 */
function entity_enable() {
  // Create cache tables for entities that support Entity cache module.
  entity_entitycache_installed_modules();
}

/**
 * Implements hook_uninstall().
 */
function entity_uninstall() {
  // Delete variables.
  variable_del('entity_rebuild_on_flush');
}

/**
 * The entity API modules have been merged into a single module.
 */
function entity_update_7000() {
  // This empty update is required such that all caches are cleared as
  // necessary.
}

/**
 * Remove the deprecated 'entity_defaults_built' variable.
 */
function entity_update_7001() {
  variable_del('entity_defaults_built');
}

/**
 * Clear caches and rebuild registry.
 */
function entity_update_7002() {
  // Do nothing, update.php clears cache for us in case there is an update.
}

/**
 * Create cache tables for entities that support Entity cache module.
 */
function entity_update_7003() {
  entity_entitycache_installed_modules();
}

/**
 * Create cache tables for entities of modules that support Entity cache module.
 *
 * @param $modules
 *   (optional) An array of module names that have been installed.
 *   If not specified, try to add cache tables for all modules.
 */
function entity_entitycache_installed_modules($modules = NULL) {
  if (!module_exists('entitycache')) {
    return;
  }

  // If no modules are specified or if entitycache is being installed,
  // try to add entitycache tables for supporting entities of all modules.
  if (!isset($modules) || in_array('entitycache', $modules)) {
    $modules = module_list();
  }

  // Get all installed modules that support entity cache.
  $entitycache_module_info = _entity_entitycache_get_module_info($modules);

  // For uninstallation of modules, we need to keep a list of tables we created
  // per module providing the entity type.
  $tables_created = variable_get('entity_cache_tables_created');

  foreach ($entitycache_module_info as $module => $module_entitycache_entities) {
    foreach ($module_entitycache_entities as $entity_type => $entity_info) {
      // Do not break modules that create the cache tables for themselves.
      if (!db_table_exists('cache_entity_' . $entity_type)) {
        $schema = drupal_get_schema_unprocessed('system', 'cache');
        $schema['description'] = 'Cache table used to store' . $entity_type . ' entity records.';
        db_create_table('cache_entity_' . $entity_type, $schema);
        $tables_created[$module][] = 'cache_entity_' . $entity_type;
      }
    }
  }
  variable_set('entity_cache_tables_created', $tables_created);
}

/**
 * Remove entity cache tables for entity types of uninstalled modules.
 *
 * @param $modules
 *   (optional) An array of uninstalled modules. If not specified, try to remove
 *   cache tables for all modules.
 */
function entity_entitycache_uninstalled_modules($modules = NULL) {
  // If no modules are specified or if entitycache is being uninstalled,
  // try to remove entitycache tables for supporting entities of all modules.
  if (!isset($modules) || in_array('entitycache', $modules)) {
    $modules = module_list();
  }
  $tables_created = variable_get('entity_cache_tables_created');
  foreach ($modules as $module) {
    if (!empty($tables_created[$module])) {
      foreach ($tables_created[$module] as $table) {
        db_drop_table($table);
      }
      unset($tables_created[$module]);
    }
  }
  variable_set('entity_cache_tables_created', $tables_created);
}

/**
 * Helper to fetch entity info about entity types that use caching.
 */
function _entity_entitycache_get_module_info($modules) {
  // Prepare a keyed array of all modules with their entity types and infos.
  // Structure: [module][entity][info]
  $entity_crud_info = entity_crud_get_info();
  $info = array();
  foreach ($entity_crud_info as $entity_name => $entity_info) {
    // Make sure that the entity info specifies a module and supports entitycache.
    if (!isset($entity_info['module']) || empty($entity_info['entity cache'])) {
      continue;
    }
    $module = $entity_info['module'];
    // Only treat installed modules.
    if (!in_array($module, $modules)) {
      continue;
    }
    // Add the entity info to the module key.
    if (!isset($info[$module])) {
      $info[$module] = array();
    }
    $info[$module][$entity_name] = $entity_info;
  }
  return $info;
}