<?php
/**
 * @file
 * Variable API module - Database storage
 *
 * This module provides database storage for variable realms
 */

/**
 * Get variable store
 */
function &variable_store($realm, $key) {
  $variable_store = &drupal_static('variable_store');

  if (!isset($variable_store[$realm][$key])) {
    $variable_store[$realm][$key] = _variable_store_load($realm, $key);
  }
  return $variable_store[$realm][$key];
}

/**
 * Implementation of hook_boot()
 */
function variable_store_boot() {
  // Do nothing, we just want this module to be available for boot.
}

/**
 * Delete variable from db
 */
function variable_store_del($realm, $key, $name) {
  $store = &variable_store($realm, $key);
  db_delete('variable_store')
    ->condition('realm', $realm)
    ->condition('realm_key', $key)
    ->condition('name', $name)
    ->execute();
  unset($store[$name]);
  cache_clear_all('variable:' . $realm . ':' . $key, 'cache_bootstrap');
}

/**
 * Get single variable from store
 */
function variable_store_get($realm, $key, $name, $default = NULL) {
  $variables = variable_store($realm, $key);
  return $variables && isset($variables[$name]) ? $variables[$name] : $default;
}

/**
 * Delete realm variable or full realm from store.
 *
 * @param $realm
 *   Realm name to delete. NULL to delete all realms.
 * @param $key
 *   Realm key to delete. NULL to delete all realm keys.
 * @param $name
 *   Variable name to delete. NULL to delete all variables for that realm, key
 */
function variable_store_delete_all($realm, $key, $name = NULL) {
  _variable_store_reset();
  $query = db_delete('variable_store');
  if (isset($realm)) {
    $query->condition('realm', $realm);
  }
  if (isset($key)) {
    $query->condition('realm_key', $key);
  }
  if (isset($name)) {
    $query->condition('name', $name);
  }
  return $query->execute();
}

/**
 * List all variable names from a realm.
 *
 * @param $realm
 *   Realm name to list. NULL to list all realms.
 * @param $key
 *   Realm key to list. NULL to list all realm keys.
 *
 * @return array
 *   List of variable names.
 */
function variable_store_list_all($realm, $key = NULL) {
  $query = db_select('variable_store', 'vs')
    ->fields('vs', array('name'))
    ->distinct();
  if ($realm) {
    $query->condition('realm', $realm);
  }
  if ($key) {
    $query->condition('realm_key', $key);
  }
  return $query->execute()->fetchCol();
}

/**
 * Load realm from db store
 */
function _variable_store_load($realm, $key) {
  $cacheid = 'variable:' . $realm . ':' . $key;
  if ($cached = cache_get($cacheid, 'cache_bootstrap')) {
    $variables = $cached->data;
  }
  else {
    $result = db_select('variable_store', 's')
      ->fields('s', array('name', 'value', 'serialized'))
      ->condition('realm', $realm)
      ->condition('realm_key', $key)
      ->execute();
    $variables = array();
    foreach ($result as $variable) {
      $variables[$variable->name] = $variable->serialized ? unserialize($variable->value) : $variable->value;
    }
    cache_set($cacheid, $variables, 'cache_bootstrap');
  }
  return $variables;
}

/**
 * Reset caches and static variables.
 */
function _variable_store_reset() {
  $store =  &drupal_static('variable_store', array());
  foreach ($store as $realm => &$realm_store) {
    foreach (array_keys($realm_store) as $key) {
      $realm_store[$key] = NULL;
    }
  }
  cache_clear_all('variable:', 'cache_bootstrap', TRUE);
}

/**
 * Set variable value
 */
function variable_store_set($realm, $key, $name, $value, $rebuild = TRUE) {
  $store = &variable_store($realm, $key);
  $serialize = !is_int($value) && !is_string($value);
  db_merge('variable_store')
    ->key(array('realm' => $realm, 'realm_key' => $key, 'name' => $name))
    ->fields(array('value' => $serialize ? serialize($value) : $value, 'serialized' => $serialize ? 1 : 0))
    ->execute();
  cache_clear_all('variable:' . $realm . ':' . $key, 'cache_bootstrap');
  $store[$name] = $value;
}