<?php
/** This class permit to cache the ouptut of a code. If the cache is already
    available, use it.
    It resend the headers as the ouptut send them
    Use it by :
       $c = new cacheoutput ("URL");
    Don't forget to define a variable or the cache saved is always empty */
class cacheoutput
{
  /** Record if the saving of pages is on going */
  private $saving = false;
  /** The called id */
  private $id = null;
  /** The called ttl */
  private $ttl = null;
  /** The cache object */
  private $cache = null;
  /** Current path at start due to lack of information in __destruct*/
  private $cacheCWD = null;

  /** 
      @param string $id The cache identifier
      @param integer|null $ttl The cache Time to Leave in seconds (60s by
                               default)
      @param string|null $method The cache method to use */
  public function __construct ($id, $ttl=60, $method="file")
  {
    $res = @include ("domframework/cache$method.php");
    if ($res === false)
      throw new Exception (sprintf (_("Unkwnown cache method : "), $method),
                           500);
    $this->id = $id;
    $this->ttl = $ttl;
    $this->cacheCWD = getcwd();
    $cachemethod = "cache$method";
    $this->cache = new $cachemethod ();
    $res = $this->cache->read ($id);
    // If there is a cache : display it
    if ($res !== false)
    {
      foreach ($res["headers"] as $header)
        @header ($header);
      echo $res["content"];
      exit;
    }

    ob_start ();
    $this->saving = true;
    // The datas are sent automatically
  }

  /** End of saving the datas in cache */
  public function __destruct ()
  {
    // Force the path because it return to / in the destructor
    chdir ($this->cacheCWD);
    if ($this->saving === true)
    {
      // Do the saving of the datas
      $datas = array ("content"=>ob_get_contents (),
                      "headers"=>headers_list ());
      $this->cache->write ($this->id, $datas, $this->ttl);
    }
  }
}