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