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   1  <?php
   2  
   3  /**
   4   * FeedCreator is the abstract base implementation for concrete
   5   * implementations that implement a specific format of syndication.
   6   *
   7   * @author  Kai Blankenhorn <kaib@bitfolge.de>
   8   * @since   1.4
   9   */
  10  abstract class FeedCreator extends HtmlDescribable
  11  {
  12  
  13      /**
  14       * Mandatory attributes of a feed.
  15       */
  16      public $title, $description, $link;
  17      public $format = 'BASE';
  18  
  19      /**
  20       * Optional attributes of a feed.
  21       */
  22      public $syndicationURL, $image, $language, $copyright, $pubDate, $lastBuildDate, $editor, $editorEmail, $webmaster, $category, $docs, $ttl, $rating, $skipHours, $skipDays;
  23  
  24      /**
  25       * The url of the external xsl stylesheet used to format the naked rss feed.
  26       * Ignored in the output when empty.
  27       */
  28      public $xslStyleSheet = "";
  29  
  30      public $cssStyleSheet = "";
  31  
  32      /** @var FeedItem[] */
  33      public $items = Array();
  34  
  35      /**
  36       * Generator string
  37       */
  38      public $generator = "info@mypapit.net";
  39  
  40      /**
  41       * This feed's MIME content type.
  42       *
  43       * @since  1.4
  44       * @access private
  45       */
  46      protected $contentType = "application/xml";
  47  
  48      /**
  49       * This feed's character encoding.
  50       *
  51       * @since 1.6.1
  52       */
  53      protected $encoding = "UTF-8"; //"ISO-8859-1";
  54  
  55      /**
  56       * Any additional elements to include as an associated array. All $key => $value pairs
  57       * will be included unencoded in the feed in the form
  58       *     <$key>$value</$key>
  59       * Again: No encoding will be used! This means you can invalidate or enhance the feed
  60       * if $value contains markup. This may be abused to embed tags not implemented by
  61       * the FeedCreator class used.
  62       */
  63      public $additionalElements = Array();
  64  
  65      /**
  66       * Adds a FeedItem to the feed.
  67       *
  68       * @param FeedItem $item The FeedItem to add to the feed.
  69       */
  70      public function addItem($item)
  71      {
  72          $this->items[] = $item;
  73      }
  74  
  75      /**
  76       * Get the version string for the generator
  77       *
  78       * @return string
  79       */
  80      public function version()
  81      {
  82          return FEEDCREATOR_VERSION." (".$this->generator.")";
  83      }
  84  
  85      /**
  86       * Truncates a string to a certain length at the most sensible point.
  87       * First, if there's a '.' character near the end of the string, the string is truncated after this character.
  88       * If there is no '.', the string is truncated after the last ' ' character.
  89       * If the string is truncated, " ..." is appended.
  90       * If the string is already shorter than $length, it is returned unchanged.
  91       *
  92       * @param string $string A string to be truncated.
  93       * @param int $length    the maximum length the string should be truncated to
  94       * @return string the truncated string
  95       */
  96      public static function iTrunc($string, $length)
  97      {
  98          if (strlen($string) <= $length) {
  99              return $string;
 100          }
 101  
 102          $pos = strrpos($string, ".");
 103          if ($pos >= $length - 4) {
 104              $string = substr($string, 0, $length - 4);
 105              $pos = strrpos($string, ".");
 106          }
 107          if ($pos >= $length * 0.4) {
 108              return substr($string, 0, $pos + 1)." ...";
 109          }
 110  
 111          $pos = strrpos($string, " ");
 112          if ($pos >= $length - 4) {
 113              $string = substr($string, 0, $length - 4);
 114              $pos = strrpos($string, " ");
 115          }
 116          if ($pos >= $length * 0.4) {
 117              return substr($string, 0, $pos)." ...";
 118          }
 119  
 120          return substr($string, 0, $length - 4)." ...";
 121  
 122      }
 123  
 124      /**
 125       * Creates a comment indicating the generator of this feed.
 126       * The format of this comment seems to be recognized by
 127       * Syndic8.com.
 128       */
 129      protected function _createGeneratorComment()
 130      {
 131          return "<!-- generator=\"".FEEDCREATOR_VERSION."\" -->\n";
 132      }
 133  
 134      /**
 135       * Creates a string containing all additional elements specified in
 136       * $additionalElements.
 137       *
 138       * @param array $elements      an associative array containing key => value pairs
 139       * @param string $indentString a string that will be inserted before every generated line
 140       * @return string the XML tags corresponding to $additionalElements
 141       */
 142      protected function _createAdditionalElements($elements, $indentString = "")
 143      {
 144          $ae = "";
 145          if (is_array($elements)) {
 146              foreach ($elements AS $key => $value) {
 147                  $ae .= $indentString."<$key>$value</$key>\n";
 148              }
 149          }
 150  
 151          return $ae;
 152      }
 153  
 154      protected function _createStylesheetReferences()
 155      {
 156          $xml = "";
 157          if (!empty($this->cssStyleSheet)) {
 158              $xml .= "<?xml-stylesheet href=\"".$this->cssStyleSheet."\" type=\"text/css\"?>\n";
 159          }
 160          if (!empty($this->xslStyleSheet)) {
 161              $xml .= "<?xml-stylesheet href=\"".$this->xslStyleSheet."\" type=\"text/xsl\"?>\n";
 162          }
 163  
 164          return $xml;
 165      }
 166  
 167      /**
 168       * Builds the feed's text.
 169       *
 170       * @return string the feed's complete text
 171       */
 172      abstract public function createFeed();
 173  
 174      /**
 175       * Generate a filename for the feed cache file. The result will be $_SERVER["SCRIPT_NAME"] with the extension changed
 176       * to .xml. For example: echo $_SERVER["SCRIPT_NAME"]."\n"; echo FeedCreator::_generateFilename(); would produce:
 177       * /rss/latestnews.php
 178       * latestnews.xml
 179       *
 180       * @return string the feed cache filename
 181       * @since  1.4
 182       * @access private
 183       */
 184      protected function _generateFilename()
 185      {
 186          $fileInfo = pathinfo($_SERVER["SCRIPT_NAME"]);
 187  
 188          return substr($fileInfo["basename"], 0, -(strlen($fileInfo["extension"]) + 1)).".xml";
 189      }
 190  
 191      /**
 192       * Send given file to Browser
 193       *
 194       * @since 1.4
 195       * @param string $filename
 196       */
 197      protected function _redirect($filename)
 198      {
 199          // attention, heavily-commented-out-area
 200  
 201          // maybe use this in addition to file time checking
 202          //header("Expires: ".date("r",time()+$this->_timeout));
 203  
 204          /* no caching at all, doesn't seem to work as good:
 205           header("Cache-Control: no-cache");
 206          header("Pragma: no-cache");
 207          */
 208  
 209          // HTTP redirect, some feed readers' simple HTTP implementations don't follow it
 210          //header("Location: ".$filename);
 211  
 212          header("Content-Type: ".$this->contentType."; charset=".$this->encoding."; filename=".basename($filename));
 213          if (preg_match('/\.(kml|gpx)$/', $filename)) {
 214              header("Content-Disposition: attachment; filename=".basename($filename));
 215          } else {
 216              header("Content-Disposition: inline; filename=".basename($filename));
 217          }
 218          readfile($filename);
 219          exit();
 220      }
 221  
 222      /**
 223       * Turns on caching and checks if there is a recent version of this feed in the cache.
 224       * If there is, an HTTP redirect header is sent.
 225       * To effectively use caching, you should create the FeedCreator object and call this method
 226       * before anything else, especially before you do the time consuming task to build the feed
 227       * (web fetching, for example).
 228       *
 229       * @since 1.4
 230       * @param string $filename optional    the filename where a recent version of the feed is saved. If not specified,
 231       *                         the filename is $_SERVER["SCRIPT_NAME"] with the extension changed to .xml (see
 232       *                         _generateFilename()).
 233       * @param int $timeout     optional    the timeout in seconds before a cached version is refreshed (defaults to
 234       *                         3600 = 1 hour)
 235       */
 236      public function useCached($filename = "", $timeout = 3600)
 237      {
 238          $this->_timeout = $timeout;
 239          if ($filename == "") {
 240              $filename = $this->_generateFilename();
 241          }
 242          if (file_exists($filename) AND (time() - filemtime($filename) < $timeout)) {
 243              $this->_redirect($filename);
 244          }
 245      }
 246  
 247      /**
 248       * Saves this feed as a file on the local disk. After the file is saved, a redirect
 249       * header may be sent to redirect the user to the newly created file.
 250       *
 251       * @since 1.4
 252       * @param string $filename      optional    the filename where a recent version of the feed is saved. If not
 253       *                              specified, the filename is $_SERVER["SCRIPT_NAME"] with the extension changed to .xml
 254       *                              (see _generateFilename()).
 255       * @param bool $displayContents optional    send an HTTP redirect header or not. If true, the user will be
 256       *                              automatically redirected to the created file.
 257       */
 258      public function saveFeed($filename = "", $displayContents = true)
 259      {
 260          if ($filename == "") {
 261              $filename = $this->_generateFilename();
 262          }
 263          $feedFile = fopen($filename, "w+");
 264          if ($feedFile) {
 265              fputs($feedFile, $this->createFeed());
 266              fclose($feedFile);
 267              if ($displayContents) {
 268                  $this->_redirect($filename);
 269              }
 270          } else {
 271              echo "<br /><b>Error creating feed file, please check write permissions.</b><br />";
 272          }
 273      }
 274  }