<?php

/* Cache Script by Kyle Slattery (http://kyleslattery.com)
   You are free to use, modify, and distribute this script.
   All I ask is that you keep this message at the top (though
   it's not necessary).

   TO USE:
   Include this file in the script you want cached and wrap your code like so:
   
      start_cache();
      // your code
      stop_cache();
      
  Make sure to set the $cache_dir and $cache_time variables below.

*/

// CACHE FUNCTIONS

$cache_dir = '/server/path/to/your/cache/directory'; // leave off the slash at the end
$cache_time = 15*60; // 15 minutes in seconds

function cache_key() {
  $keys = array();
  foreach($_GET as $key => $value) {
    $keys[] = $key . "=" . $value;
  }
  sort($keys);
  return md5(implode('&', $keys));
}

function cache_filename() {
  global $cache_dir;
  return $cache_dir . '/' . cache_key() . '.cache';
}

function cache_exists() {
  global $cache_time;
  
  if(@file_exists(cache_filename()) && time() - $cache_time < @filemtime(cache_filename())) {
    return true;
  } else {
    return false;
  }
}

function read_cache() {
  return file_get_contents(cache_filename());
}

function save_cache($value) {
  $fp = @fopen(cache_filename(), 'w');
  @fwrite($fp, $value);
  @fclose($fp);
}

function start_cache() {
  if(cache_exists()) {
    echo read_cache();
    exit();
  } else {
    ob_start();
  }
}

function stop_cache() {
  $data = ob_get_clean();
  save_cache($data);
  echo $data;
}

?>