<?php
/**
 * @file cacherouter.inc
 *   Defines the cacherouter module
 */
require dirname(__FILE__) .'/CacheRouter.php';

// We default this to true, and let the engines determine if they can implement it.  (e.g. db can't.)
$conf += array('page_cache_fastpath' => TRUE);

/**
 * Return data from the persistent cache. Data may be stored as either plain text or as serialized data.
 * cache_get will automatically return unserialized objects and arrays.
 *
 * @param $cid
 *   The cache ID of the data to retrieve.
 * @param $table
 *   The table $table to store the data in. Valid core values are 'cache_filter',
 *   'cache_menu', 'cache_page', or 'cache' for the default cache.
 */
function cache_get($cid, $table = 'cache') {
  global $cache;
  if (!isset($cache)) {
    $cache = new CacheRouter();
  }
  return $cache->get($cid, $table);
}

/**
 * Store data in the persistent cache.
 *
 * The persistent cache is split up into four database
 * tables. Contributed modules can add additional tables.
 *
 * 'cache_page': This table stores generated pages for anonymous
 * users. This is the only table affected by the page cache setting on
 * the administrator panel.
 *
 * 'cache_menu': Stores the cachable part of the users' menus.
 *
 * 'cache_filter': Stores filtered pieces of content. This table is
 * periodically cleared of stale entries by cron.
 *
 * 'cache': Generic cache storage table.
 *
 * The reasons for having several tables are as follows:
 *
 * - smaller tables allow for faster selects and inserts
 * - we try to put fast changing cache items and rather static
 *   ones into different tables. The effect is that only the fast
 *   changing tables will need a lot of writes to disk. The more
 *   static tables will also be better cachable with MySQL's query cache
 *
 * @param $cid
 *   The cache ID of the data to store.
 * @param $data
 *   The data to store in the cache. Complex data types will be automatically serialized before insertion.
 *   Strings will be stored as plain text and not serialized.
 * @param $table
 *   The table $table to store the data in. Valid core values are 'cache_filter',
 *   'cache_menu', 'cache_page', or 'cache'.
 * @param $expire
 *   One of the following values:
 *   - CACHE_PERMANENT: Indicates that the item should never be removed unless
 *     explicitly told to using cache_clear_all() with a cache ID.
 *   - CACHE_TEMPORARY: Indicates that the item should be removed at the next
 *     general cache wipe.
 *   - A Unix timestamp: Indicates that the item should be kept at least until
 *     the given time, after which it behaves like CACHE_TEMPORARY.
 * @param $headers
 *   A string containing HTTP header information for cached pages.
 */
function cache_set($cid, $value, $table = 'cache', $expire = CACHE_PERMANENT, $headers = NULL) {
  global $cache;
  if (!isset($cache)) {
    $cache = new CacheRouter();
  }
  return $cache->set($cid, $value, $expire, $headers, $table);
}

/**
 *
 * Expire data from the cache. If called without arguments, expirable
 * entries will be cleared from the cache_page and cache_block tables.
 *
 * @param $cid
 *   If set, the cache ID to delete. Otherwise, all cache entries that can
 *   expire are deleted.
 *
 * @param $table
 *   If set, the table $table to delete from. Mandatory
 *   argument if $cid is set.
 *
 * @param $wildcard
 *   If set to TRUE, the $cid is treated as a substring
 *   to match rather than a complete ID. The match is a right hand
 *   match. If '*' is given as $cid, the table $table will be emptied.
 */
function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) {
  global $cache;
  global $user;
  
  if (!isset($cache)) {
    $cache = new CacheRouter();
  }
  
  if (!isset($cid) && !isset($table)) {
    // Clear the block cache first, so stale data will
    // not end up in the page cache.
    $cache->flush('cache_block');
    $cache->flush('cache_page');
    return;
  }
  
  if (empty($cid)) {
    if (variable_get('cache_lifetime', 0)) {
      // We store the time in the current user's $user->cache variable which
      // will be saved into the sessions table by sess_write(). We then
      // simulate that the cache was flushed for this user by not returning
      // cached data that was cached before the timestamp.
      $user->cache = time();

      $cache_flush = variable_get('cache_flush', 0);
      if ($cache_flush == 0) {
        // This is the first request to clear the cache, start a timer.
        variable_set('cache_flush', time());
      }
      else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) {
        // Clear the cache for everyone, cache_flush_delay seconds have
        // passed since the first request to clear the cache.
        $cache->flush($table);
        variable_set('cache_flush', 0);
      }
    }
    else {
      // No minimum cache lifetime, flush all temporary cache entries now.
      $cache->flush($table);
    }
  }
  else {
    if ($wildcard) {
      if ($cid == '*') {
        $cache->delete('*', $table);
      }
      else {
        $cache->delete($cid . '*', $table);
      }
    }
    else {
      $cache->delete($cid, $table);
    }
  }
  
}

/**
 * Main callback from DRUPAL_BOOTSTRAP_EARLY_PAGE_CACHE phase
 */
function page_cache_fastpath() {
  global $base_root;
  global $cache;
  if (empty($_POST) && !$_COOKIE['cacherouter']) {
    if (!isset($cache)) {
      $cache = new CacheRouter();
    }
    if ($cache->page_fast_cache('cache_page')) {
      $page = $cache->get($base_root . request_uri(), 'cache_page');
      if (!empty($page)) {
        drupal_page_header();
        if (function_exists('gzencode')) {
          header('Content-Encoding: gzip');
        }
        print $page->data;
        return TRUE;
      }
    }
  }
  return FALSE;
}