islandora/includes/mime_detect.inc

<?php


/**
 * @file
 *
 * Replacement for the original islandora MimeClass.
 * Does essentially the same thing, just using the built in drupal 7
 * mime system.
 *
 * A nice added bonus is that this new class will put a note in watchdog when
 * it encounters a filetype it doesnt know.
 *
 */

class MimeDetect {

  private $mime_types;
  private $ext_types;

  /**
   * Construtor
   */
  public function __construct() {
    //Drupal returns the mimetype list as a double assoc array with two entries:
    //mimetypes: Integer array of mimetypes
    //extensions: Assoc array of extensions
    //
    //The extension array can be used as a key to get the value in the mimetypes
    //array.
    //
    //Example  if $extensions['png'] == 5, then $mimetypes[5] = 'image/png'
    //we want to combine this into 1 array for easy access.

    $temp = file_mimetype_mapping();

    $temp_mime_types = $temp['mimetypes'];
    $temp_mime_ext = $temp['extensions'];

    //free the memory in temp since we don't need it anymore
    unset($temp);

    //combine the two arrays into one.
    foreach ($temp_mime_ext as $key => $val ) {
      $this->mime_types[$key] = $temp_mime_types[$val];
    }

    //flip the mime_type array to make the ext array
    $this->ext_types = array_flip($this->mime_types);
  }

  /**
   * function: getType
   * description: An alias to get_mimetype,
   * for backwards-compatibility with our old mimetype class.
   *
   * @param type $filename
   * @return type
  */
    function getType($filename) {
      return $this->getMimetype($filename);
  }

  /**
   * function: get_mimetype
   * description: returns a mimetype associated with the
   *   file extension of $filename
   *
   * @param type $filename
   * @param type $debug
   * @return string
   *   mimetype associated with the file extension of $filename
   */
  public function getMimetype($filename, $debug = FALSE) {
    //the file extension will be the last index in the exploded string
    $ext = @end(explode('.' , $filename));
    $ext = strtolower($ext);

    //check the array for a predetermined mime type. If not found, add a warning
    //to the watch dog and use the system command to get a value
    if (!empty($this->mime_types[$ext])) {
      if (TRUE === $debug) {
        $return_type = $this->mime_types[$ext];
        return array('mime_type' => $return_type, 'method' => 'from_array');
      }
    
      return $this->mime_types[$ext];
    }
    else {
      //this file was not in the drupal mime system.
      //add a line to the watchdog informing us of this incident
      $err_msg = 'Found a file extension not covered in the drupal mime func:';
      watchdog('MimeClass', $err_msg . $ext );
    }

    //by default return application octet stream
    if (TRUE == $debug) {
      return array('mime_type' => 'application/octet-stream', 'method' => 'last_resort');
    }
      
    return 'application/octet-stream';
  }

  /**
   * function: get_extension
   * description: returns *one* valid file extension for a given $mime_type
   *
   * @param type $mime_type
   * @param type $debug
   * @return type
   */
  public function getExtension($type, $debug = FALSE) {
    
    if (!empty($this->ext_types[$type])) {
      if (TRUE == $debug) {
        return array('extension' => $this->ext_types[$type], 'method' => 'from_array');
        }
      return $this->ext_types[$type];
    }
    else{
      //return bin by default... this could cause errors if handled incorrectly
      //and probably should return false or -1 or something to be handled 
      //client side.
      if (TRUE == $debug) {
        return array('extension' => 'bin', 'method' => 'last_resort');
      }
      return 'bin';
    }
  }

}