<?php
  
  namespace Guzzle\Cache;
  
  /**
   * Cache adapter that defers to closures for implementation
   */
  class ClosureCacheAdapter implements CacheAdapterInterface
  {
      /**
       * @var array Mapping of method names to callables
       */
      protected $callables;
  
      /**
       * The callables array is an array mapping the actions of the cache adapter to callables.
       * - contains: Callable that accepts an $id and $options argument
       * - delete:   Callable that accepts an $id and $options argument
       * - fetch:    Callable that accepts an $id and $options argument
       * - save:     Callable that accepts an $id, $data, $lifeTime, and $options argument
       *
       * @param array $callables array of action names to callable
       *
       * @throws \InvalidArgumentException if the callable is not callable
       */
      public function __construct(array $callables)
      {
          // Validate each key to ensure it exists and is callable
          foreach (array('contains', 'delete', 'fetch', 'save') as $key) {
              if (!array_key_exists($key, $callables) || !is_callable($callables[$key])) {
                  throw new \InvalidArgumentException("callables must contain a callable {$key} key");
              }
          }
  
          $this->callables = $callables;
      }
  
      public function contains($id, array $options = null)
      {
          return call_user_func($this->callables['contains'], $id, $options);
      }
  
      public function delete($id, array $options = null)
      {
          return call_user_func($this->callables['delete'], $id, $options);
      }
  
      public function fetch($id, array $options = null)
      {
          return call_user_func($this->callables['fetch'], $id, $options);
      }
  
      public function save($id, $data, $lifeTime = false, array $options = null)
      {
          return call_user_func($this->callables['save'], $id, $data, $lifeTime, $options);
      }
  }