<?php
/**
 * $Id$
 *
 * @file
 *   MongoDB engine class.
 */

class mongodbCacheRouterEngine extends CacheRouterEngine {
  var $collection;
  
  function page_fast_cache() {
    return $this->fast_cache;
  }

  /**
   * Completely override parent method to remove stuff we don't need (locking,
   *  lookup etc).
   */
  function __construct($bin, $options, $default_options) {
    $this->name = $bin;
    
    // Setup our prefixes so that we can prefix a particular bin, or if not set use the default prefix.
    if (isset($options['prefix'])) {
      $this->prefix = $options['prefix'];
    }
    elseif (!empty($default_options['prefix'])) {
      $this->prefix = $default_options['prefix'];
    }
    
    // This allows us to turn off fast_cache for cache_page so that we can get anonymous statistics.
    if (isset($options['fast_cache'])) {
      $this->fast_cache = $default_options['fast_cache'];
    }
    elseif (isset($default_options['fast_cache'])) {
      $this->fast_cache = $default_options['fast_cache'];
    }
    
    // This allows us to turn off static content caching for modules/bins that are already doing this.
    if (isset($options['static'])) {
      $this->static = $options['static'];
    }
    elseif (isset($default_options['static'])) {
      $this->static = $default_options['static'];
    }
    
    include_once('sites/all/modules/mongodb/mongodb.module');
    $collection_name = $this->prefix . '-' . $bin;
    $this->collection = mongodb_collection($collection_name);
  }

  function get($key) {
    // Attempt to pull from static cache.
    $cache = parent::get($this->key($key));
    if (isset($cache)) {
      return $cache;
    }

    // Garbage collection necessary when enforcing a minimum cache lifetime.
    $this->garbageCollection();
    
    $cache = $this->collection->findOne(array('_id' => (string)$key));
    
    // Prepare cache object
    unset($cache['_id']);
    $cache = (object)$cache;
    if ($cache->serialized) {
      $cache->data = unserialize($cache->data);
    }
    
    // Update static cache
    parent::set($this->key($key), $cache);
    
    return $cache;
  }
  
  /**
   * Garbage collection for get().
   */
  protected function garbageCollection() {
    global $user;

    // Garbage collection necessary when enforcing a minimum cache lifetime.
    $cache_flush = variable_get('cache_flush_' . $this->name, 0);
    if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= $_SERVER['REQUEST_TIME'])) {
      // Reset the variable immediately to prevent a meltdown in heavy load situations.
      variable_set('cache_flush_' . $this->name, 0);
      // Time to flush old cache data
      $find = array('expire' => array('$lte' => $cache_flush, '$ne' => CACHE_PERMANENT));
      $this->collection->remove($find);
    }
  }  
  
  function set($key, $data, $expire = CACHE_PERMANENT, $headers = NULL) {
    $scalar = is_scalar($data);
    
    $entry = array(
      '_id' => (string)$key,
      'cid' => (string)$key,
      'created' => $_SERVER['REQUEST_TIME'],
      'expire' => $expire,
      'headers' => $headers,
      'serialized' => !$scalar,
      'data' => $scalar ? $data : serialize($data),
    );
        
    if (!empty($key)) {
      $this->collection->save($entry);
    }
  }  
  
  function delete($key) {
    // Delete from static cache
    parent::flush();
    
    if ($key == '*') {
      // Whole bin delete
      $this->collection->remove();
    }
    elseif (substr($key, strlen($key) - 1, 1) == '*') {
      // Wildcard delete
      $cid = $this->key(substr($key, 0, strlen($key) - 1));
      $this->collection->remove(array('cid' => new MongoRegex('/'. preg_quote($cid) .'.*/')));
    }
    else {
      // Single entry delete
      $this->collection->remove(array('_id' => (string)$key));
    }
  }

  function flush() {
    $this->collection->remove(array('expire' => array('$ne' => CACHE_PERMANENT, '$lte' => $_SERVER['REQUEST_TIME'])));
  }
}