<?php
 /*
     pCache - speed up the rendering by caching up the pictures

     Version     : 2.1.0
     Made by     : Jean-Damien POGOLOTTI
     Last Update : 26/01/11

     This file can be distributed under the license you can find at :

                       http://www.pchart.net/license

     You can find the whole class documentation on the pChart web site.
 */

 /* pData class definition */
 class pCache
  {
   var $CacheFolder;
   var $CacheIndex;
   var $CacheDB;

   /* Class creator */
   function pCache($Settings="")
    {
     $CacheFolder	= isset($Settings["CacheFolder"]) ? $Settings["CacheFolder"] : "cache";
     $CacheIndex	= isset($Settings["CacheIndex"]) ? $Settings["CacheIndex"] : "index.db";
     $CacheDB		= isset($Settings["CacheDB"]) ? $Settings["CacheDB"] : "cache.db";

     $this->CacheFolder	= $CacheFolder;
     $this->CacheIndex	= $CacheIndex;
     $this->CacheDB	= $CacheDB;

     if (!file_exists($this->CacheFolder."/".$this->CacheIndex)) { touch($this->CacheFolder."/".$this->CacheIndex); }
     if (!file_exists($this->CacheFolder."/".$this->CacheDB))    { touch($this->CacheFolder."/".$this->CacheDB); }
    }

   /* Flush the cache contents */
   function flush()
    {
     if (file_exists($this->CacheFolder."/".$this->CacheIndex)) { unlink($this->CacheFolder."/".$this->CacheIndex); touch($this->CacheFolder."/".$this->CacheIndex); }
     if (file_exists($this->CacheFolder."/".$this->CacheDB))    { unlink($this->CacheFolder."/".$this->CacheDB); touch($this->CacheFolder."/".$this->CacheDB); }
    }

   /* Return the MD5 of the data array to clearly identify the chart */
   function getHash($Data,$Marker="")
    { return(md5($Marker.serialize($Data->Data))); }

   /* Write the generated picture to the cache */
   function writeToCache($ID,$pChartObject)
    {
     /* Compute the paths */
     $TemporaryFile = $this->CacheFolder."/tmp_".rand(0,1000).".png";
     $Database      = $this->CacheFolder."/".$this->CacheDB;
     $Index         = $this->CacheFolder."/".$this->CacheIndex;

     /* Flush the picture to a temporary file */
     imagepng($pChartObject->Picture ,$TemporaryFile);

     /* Retrieve the files size */
     $PictureSize = filesize($TemporaryFile);
     $DBSize      = filesize($Database);

     /* Save the index */
     $Handle = fopen($Index,"a");
     fwrite($Handle, $ID.",".$DBSize.",".$PictureSize.",".time().",0      \r\n");
     fclose($Handle);

     /* Get the picture raw contents */
     $Handle = fopen($TemporaryFile,"r");
     $Raw    = fread($Handle,$PictureSize);
     fclose($Handle);

     /* Save the picture in the solid database file */
     $Handle = fopen($Database,"a");
     fwrite($Handle, $Raw);
     fclose($Handle);

     /* Remove temporary file */
     unlink($TemporaryFile);
    }

   /* Remove object older than the specified TS */
   function removeOlderThan($Expiry)
    { $this->dbRemoval(array("Expiry"=>$Expiry)); }

   /* Remove an object from the cache */
   function remove($ID)
    { $this->dbRemoval(array("Name"=>$ID)); }

   /* Remove with specified criterias */
   function dbRemoval($Settings)
    {
     $ID     = isset($Settings["Name"]) ? $Settings["Name"] : NULL;
     $Expiry = isset($Settings["Expiry"]) ? $Settings["Expiry"] : -(24*60*60);
     $TS     = time()-$Expiry;

     /* Compute the paths */
     $Database     = $this->CacheFolder."/".$this->CacheDB;
     $Index        = $this->CacheFolder."/".$this->CacheIndex;
     $DatabaseTemp = $this->CacheFolder."/".$this->CacheDB.".tmp";
     $IndexTemp    = $this->CacheFolder."/".$this->CacheIndex.".tmp";

     /* Single file removal */
     if ( $ID != NULL )
      {
       /* Retrieve object informations */
       $Object = $this->isInCache($ID,TRUE);

       /* If it's not in the cache DB, go away */
       if ( !$Object ) { return(0); }
      }

     /* Create the temporary files */
     if (!file_exists($DatabaseTemp)) { touch($DatabaseTemp); }
     if (!file_exists($IndexTemp))    { touch($IndexTemp); }

     /* Open the file handles */
     $IndexHandle     = @fopen($Index, "r");
     $IndexTempHandle = @fopen($IndexTemp, "w");
     $DBHandle        = @fopen($Database, "r");
     $DBTempHandle    = @fopen($DatabaseTemp, "w");

     /* Remove the selected ID from the database */
     while (!feof($IndexHandle))
      {
       $Entry    = fgets($IndexHandle, 4096);
       $Entry    = str_replace("\r","",$Entry);
       $Entry    = str_replace("\n","",$Entry);
       $Settings = preg_split("/,/",$Entry);

       if ( $Entry != "" )
        {
         $PicID       = $Settings[0];
         $DBPos       = $Settings[1];
         $PicSize     = $Settings[2];
         $GeneratedTS = $Settings[3];
         $Hits        = $Settings[4];

         if ( $Settings[0] != $ID && $GeneratedTS > $TS)
          {
           $CurrentPos  = ftell($DBTempHandle);
           fwrite($IndexTempHandle, $PicID.",".$CurrentPos.",".$PicSize.",".$GeneratedTS.",".$Hits."\r\n");

           fseek($DBHandle,$DBPos);
           $Picture = fread($DBHandle,$PicSize);
           fwrite($DBTempHandle,$Picture);
          }
        }
      }

     /* Close the handles */
     fclose($IndexHandle);
     fclose($IndexTempHandle);
     fclose($DBHandle);
     fclose($DBTempHandle);

     /* Remove the prod files */
     unlink($Database);
     unlink($Index);

     /* Swap the temp & prod DB */
     rename($DatabaseTemp,$Database);
     rename($IndexTemp,$Index);
    }

   function isInCache($ID,$Verbose=FALSE,$UpdateHitsCount=FALSE)
    {
     /* Compute the paths */
     $Index = $this->CacheFolder."/".$this->CacheIndex;

     /* Search the picture in the index file */
     $Handle = @fopen($Index, "r");
     while (!feof($Handle))
      {
       $IndexPos = ftell($Handle);
       $Entry = fgets($Handle, 4096);
       if ( $Entry != "" )
        {
         $Settings = preg_split("/,/",$Entry);
         $PicID    = $Settings[0];
         if ( $PicID == $ID )
          {
           fclose($Handle);

           $DBPos       = $Settings[1];
           $PicSize     = $Settings[2];
           $GeneratedTS = $Settings[3];
           $Hits        = intval($Settings[4]);

           if ( $UpdateHitsCount )
            {
             $Hits++;
             if ( strlen($Hits) < 7 ) { $Hits = $Hits.str_repeat(" ",7-strlen($Hits)); }

             $Handle = @fopen($Index, "r+");
             fseek($Handle,$IndexPos);
             fwrite($Handle, $PicID.",".$DBPos.",".$PicSize.",".$GeneratedTS.",".$Hits."\r\n");
             fclose($Handle);
            }

           if ($Verbose)
            { return(array("DBPos"=>$DBPos,"PicSize"=>$PicSize,"GeneratedTS"=>$GeneratedTS,"Hits"=>$Hits)); }
           else
            { return(TRUE); }
          }
        }
      }
     fclose($Handle);

     /* Picture isn't in the cache */
     return(FALSE);
    }

   function strokeFromCache($ID)
    {
     /* Get the raw picture from the cache */
     $Picture = $this->getFromCache($ID);

     /* Do we have a hit? */
     if ( $Picture == NULL ) { return(FALSE); }

     header('Content-type: image/png');
     echo $Picture;

     return(TRUE);
    }

   function saveFromCache($ID,$Destination)
    {
     /* Get the raw picture from the cache */
     $Picture = $this->getFromCache($ID);

     /* Do we have a hit? */
     if ( $Picture == NULL ) { return(FALSE); }

     /* Flush the picture to a file */
     $Handle = fopen($Destination,"w");
     fwrite($Handle,$Picture);
     fclose($Handle);

     /* All went fine */
     return(TRUE);
    }

   function getFromCache($ID)
    {
     /* Compute the path */
     $Database = $this->CacheFolder."/".$this->CacheDB;

     /* Lookup for the picture in the cache */
     $CacheInfo = $this->isInCache($ID,TRUE,TRUE);

     /* Not in the cache */
     if (!$CacheInfo) { return(NULL); }

     /* Get the database extended information */     
     $DBPos   = $CacheInfo["DBPos"];
     $PicSize = $CacheInfo["PicSize"];

     /* Extract the picture from the solid cache file */
     $Handle = @fopen($Database, "r");
     fseek($Handle,$DBPos);
     $Picture = fread($Handle,$PicSize);
     fclose($Handle);

     /* Return back the raw picture data */
     return($Picture);
    }
  }
?>