<?php
  /*
   * Project:     MagpieRSS: a simple RSS integration tool
   * File:        rss_cache.inc, a simple, rolling(no GC), cache 
   *              for RSS objects, keyed on URL.
   * Author:      Kellan Elliott-McCrea <kellan@protest.net>
   * Version:     0.51
   * License:     GPL
   *
   * The lastest version of MagpieRSS can be obtained from:
   * http://magpierss.sourceforge.net
   *
   * For questions, help, comments, discussion, etc., please join the
   * Magpie mailing list:
   * http://lists.sourceforge.net/lists/listinfo/magpierss-general
   *
   */
  
  class RSSCache {
      var $BASE\_CACHE\; =\; \text{'}./cache\text{'};$// where the cache files are stored
      var MAX_AGE    = 3600;         // when are files stale, default one hour
      var $ERROR\; =\; "";\; //\; accumulate\; error\; messages\; function\; RSSCache\; ($base='', $age=\text{'}\text{'})\; \{\; if\; ($base ) {
              $this->BASE\_CACHE\; =$base;
          }
          if ( $age\; )\; \{$this->MAX_AGE = $age;\; \}\; //\; attempt\; to\; make\; the\; cache\; directory\; if\; (\; !\; file\_exists($this->BASE_CACHE ) ) {
              $status\; =\; @mkdir($this->BASE_CACHE, 0755 );
              
              // if make failed 
              if ( ! $status\; )\; \{$this->error(
                      "Cache couldn't make dir '" . $this->BASE\_CACHE\; .\; "\text{'}."\; );\; \}\; \}\; \}$/*=======================================================================*\
      Function:   set
      Purpose:    add an item to the cache, keyed on url
      Input:      url from wich the rss file was fetched
      Output:     true on sucess  
  \*=======================================================================*/
      function set (url, $rss)\; \{$this->ERROR = "";
          $cache\_file\; =$this->file_name( $url\; );$fp = @fopen( $cache\_file,\; \text{'}w\text{'}\; );\; if\; (\; !$fp ) {
              $this->error(\; "Cache\; unable\; to\; open\; file\; for\; writing:$cache_file"
              );
              return 0;
          }
          
          
          $data\; =$this->serialize( $rss\; );\; fwrite($fp, $data\; );\; fclose($fp );
          
          return $cache\_file;\; \}$/*=======================================================================*\
      Function:   get
      Purpose:    fetch an item from the cache
      Input:      url from wich the rss file was fetched
      Output:     cached object on HIT, false on MISS 
  \*=======================================================================*/ 
      function get (url) {
          $this->ERROR\; =\; "";$cache_file = $this->file\_name($url );
          
          if ( ! file_exists( $cache\_file\; )\; )\; \{$this->debug( 
                  "Cache doesn't contain: $url\; (cache\; file:$cache_file)"
              );
              return 0;
          }
          
          $fp\; =\; @fopen($cache_file, 'r');
          if ( ! $fp\; )\; \{$this->error(
                  "Failed to open cache file for reading: $cache\_file"\; );\; return\; 0;\; \}\; if\; ($filesize = filesize($cache\_file)\; )\; \{$data = fread( $fp,\; filesize($cache_file) );
                  $rss\; =$this->unserialize( $data\; );\; return$rss;
              }
              
              return 0;
      }
  
  /*=======================================================================*\
      Function:   check_cache
      Purpose:    check a url for membership in the cache
                  and whether the object is older then MAX_AGE (ie. STALE)
      Input:      url from wich the rss file was fetched
      Output:     cached object on HIT, false on MISS 
  \*=======================================================================*/     
      function check_cache ( $url\; )\; \{$this->ERROR = "";
          $filename\; =$this->file_name( $url\; );\; if\; (\; file\_exists($filename ) ) {
              // find how long ago the file was added to the cache
              // and whether that is longer then MAX_AGE
              $mtime\; =\; filemtime($filename );
              $age\; =\; time()\; -$mtime;
              if ( $this->MAX\_AGE\; >$age ) {
                  // object exists and is current
                  return 'HIT';
              }
              else {
                  // object exists but is old
                  return 'STALE';
              }
          }
          else {
              // object does not exist
              return 'MISS';
          }
      }
  
          function cache_age( $cache\_key\; )\; \{$filename = $this->file\_name($url );
                  if ( file_exists( $filename\; )\; )\; \{$mtime = filemtime( $filename\; );$age = time() - $mtime;\; return$age;
                  }
                  else {
                          return -1;        
                  }
          }
          
  /*=======================================================================*\
      Function:   serialize
  \*=======================================================================*/     
      function serialize ( $rss\; )\; \{\; return\; serialize($rss );
      }
  
  /*=======================================================================*\
      Function:   unserialize
  \*=======================================================================*/     
      function unserialize ( $data\; )\; \{\; return\; unserialize($data );
      }
      
  /*=======================================================================*\
      Function:   file_name
      Purpose:    map url to location in cache
      Input:      url from wich the rss file was fetched
      Output:     a file name
  \*=======================================================================*/     
      function file_name ($url)\; \{$filename = md5( $url\; );\; return\; join(\; DIRECTORY\_SEPARATOR,\; array($this->BASE_CACHE, $filename\; )\; );\; \}$/*=======================================================================*\
      Function:   error
      Purpose:    register error
  \*=======================================================================*/         
      function error (errormsg, $lvl=E\_USER\_WARNING)\; \{$// append PHP's error message if track_errors enabled
          if ( isset(php_errormsg) ) { 
              $errormsg\; .=\; "\; ($php_errormsg)";
          }
          $this->ERROR\; =$errormsg;
          if ( MAGPIE_DEBUG ) {
              trigger_error( $errormsg,$lvl);
          }
          else {
              error_log( $errormsg,\; 0);\; \}\; \}\; function\; debug\; ($debugmsg, $lvl=E\_USER\_NOTICE)\; \{\; if\; (\; MAGPIE\_DEBUG\; )\; \{$this->error("MagpieRSS [debug] $debugmsg",$lvl);
          }
      }
  
  }
  
  ?>