XMLDatastream.inc

<?php

// $Id$

abstract class XMLDatastream {

  static $XMLNS = 'http://www.islandora.ca';
  static $errors = NULL;
  
  protected $xml = NULL;
  private $valid = NULL; 
  
  protected $forceSchema = FALSE; // if set, the datastream will be validated against the specified schema in self::$SCHEMA_URI instead of 
                                // reading the schema URI from the datastream.
  
  public $pid;
  public $dsid;  

 
  /**
   * Parses an PID from an identifier.
   * @param string $identifier 
   * @return string $pid
   */
  public static function getPidFromIdentifier($identifier) {
    return substr($identifier, 0, strpos($identifier, "/"));
  }

  
  /**
   * validPid
   * Validates a fedora PID based on the regexp provided in the fedora 
   * 3.3 documentation.  
   * http://www.fedora-commons.org/confluence/display/FCR30/Fedora+Identifiers
   *
   * @param String $pid
   * @return boolean $valid
   */
  public static function validPid($pid) {
    $valid = FALSE;
    if (strlen(trim($pid)) <= 64 && preg_match('/^([A-Za-z0-9]|-|\.)+:(([A-Za-z0-9])|-|\.|~|_|(%[0-9A-F]{2}))+$/', trim($pid))) {
      $valid = TRUE;
    }
    
    return $valid;
  }
  
   /**
   * validDsid
   * Validates a fedora Dsid based on the the allowed XML standard NCName. 
   * The regexp is a "regular" subset of names allowed, it excludes some extended hex characters that are
   * technically permitted.
   * http://www.fedora-commons.org/confluence/display/FCR30/Fedora+Identifiers
   *
   * @param String $pid
   * @return boolean $valid
   */
  public static function validDsid($dsid) {
    $valid = FALSE;
    if (strlen(trim($dsid)) <= 64 && preg_match('/^[a-zA-Z0-9\_\-\.]+$/', trim($dsid))) {
      $valid = TRUE;
    }
    
    return $valid;
  }
  
    
  
  /** 
   * Parses the DSID from an identifier.
   * TODO: combine this method with getPidFromIdentifier?
   * @param string $identifier 
   * @return string $dsid
   */
  public static function getDSIDFromIdentifier($identifier) {
    $temp = strstr($identifier, "/");
    return substr($temp, 1);
  }


  /**
   * Constructs an XMLDatastream object from the XML file specified.
   * Returns FALSE on failure.
   *
   * @param string $filename
   * @return XMLDatastream $cm
   */
  public static function loadFromFile($filename) {
    return new self(file_get_contents($filename));
  }


  /**
   * Constructor
   * NOTE: Use the static constructor methods whenever possible.
   *
   * @param string $xmlStr
   * @param string $pid
   * @param string $dsid
   * @return XMLDatastream $cm
   */
  public function __construct($xmlStr, $pid = NULL, $dsid = NULL) {
      libxml_use_internal_errors(true);
      $this->pid=$pid;
      $this->dsid=$dsid; 
      
      if ($xmlStr !== NULL) {
	$this->xml = (is_object($xmlStr) && get_class($xmlStr) == DOMDocument)?$xmlStr :  DOMDocument::loadXML($xmlStr);      
      }
  }


  /**
   * Gets the identifier for this XMLDatastream
   * Returns FALSE on failure.
   * 
   * NOTE: not available if constructed directly from file.
   *
   * @return string identifier
   */
  public function getIdentifier() {
    return ($this->pid != NULL && $this->dsid != NULL) ? $this->pid . '/'. $this->dsid : FALSE;
  }


  /**
   * Dumps the XMLDatastream as an XML String 
   * 
   *
   * @return string xml
   */
  public function dumpXml() {
    if ($this->xml == NULL) {
      $this->fetchXml(); 
    }
    return $this->xml->saveXml();
  }


  /**
   * Validates the XMLDatastream against the schema location 
   * defined by the xmlns:schemaLocation attribute of the root 
   * element. If the xmlns:schemaLocation attribute does not exist,
   * then it is assumed to be the old schema and it attempts to convert 
   * using the convertFromOldSchema method.
   *
   * TODO:  Maybe change it so that it always validates against a known 
   * schema.  This makes more sense because this class assumes the structure
   * to be known after it has been validated.
   *
   * @return boolean $valid
   */
  public function validate() {
    if ($this->valid === NULL) {
      $ret = TRUE;  
      if ($this->xml == NULL) {
	$this->fetchXml(); 
      }      
      // figure out if we're dealing with a new or old schema 
      $rootEl =  $this->xml->firstChild;
      if (!$rootEl->hasAttributes() || $rootEl->attributes->getNamedItem('schemaLocation') === NULL ) {
        //$tmpname = substr($this->pid, strpos($this->pid, ':') + 1);
        $tmpname = user_password(10);
        $this->convertFromOldSchema();
        drupal_add_js("fedora_repository_print_new_schema_$tmpname = function(tagID) {
  var target = document.getElementById(tagID);
  var content = target.innerHTML;
  var text = '<html><head><title>Title'   +
  '</title><body>' + content +'</body></html>';
  printerWindow = window.open('', '', 'toolbar=no,location=no,' + 'status=no,menu=no,scrollbars=yes,width=650,height=400');
  printerWindow.document.open();
printerWindow.document.write(text);
}          ", 'inline');

        drupal_set_message('<span id="new_schema_'. $tmpname .'" style="display: none;">'. htmlentities($this->xml->saveXML()) .'</span>Warning: XMLDatastream performed conversion of \''. $this->getIdentifier() .'\' from old schema.  Please update the datastream. The new datastream contents are <a href="javascript:fedora_repository_print_new_schema_'. $tmpname .'(\'new_schema_'. $tmpname .'\')">here.</a> ');
        $rootEl =  $this->xml->firstChild;
      }

      $schemaLocation = NULL;
      if ($this->forceSchema) {
        // hack because you cant easily get the static property value from 
        // a subclass.
        $vars = get_class_vars(get_class($this));
        $schemaLocation = $vars['SCHEMA_URI'];
        
      } 
      elseif ($rootEl->attributes->getNamedItem('schemaLocation') !== NULL) {
        //figure out where the schema is located and validate.
        list(, $schemaLocation) = preg_split('/\s+/', $rootEl->attributes->getNamedItem('schemaLocation')->nodeValue);
      }
     $schemaLocation = NULL;
     return TRUE;
      if ($schemaLocation !== NULL) {
        if (!$this->xml->schemaValidate($schemaLocation)) {
          $ret = FALSE;
          $errors=libxml_get_errors();
          foreach ($errors as $err) {
            self::$errors[] = 'XML Error: Line '. $err->line .': '. $err->message;
          }
        } 
        else {
          $this->name=$rootEl->attributes->getNamedItem('name')->nodeValue;
        }
      } 
      else {
        $ret = FALSE;
        self::$errors[] = 'Unable to load schema.';
      }

      $this->valid = $ret;
    }   
  
    return $this->valid;
  }  
  
  
  /**
   * Saves the current XML datastream back to fedora.   The XML must validate.
   *
   * @return boolean $success
   */  
  public function saveToFedora() {
    module_load_include('inc', 'Fedora_Repository', 'api/fedora_item');
    if ($this->validate()) {
      $item = new Fedora_Item($this->pid);
      $item->modify_datastream_by_value($this->dumpXml(), $this->dsid, $this->name, NULL);
      return TRUE; 
    }
    return FALSE;
  }

  /**
   * Purges veersions of the datastream newer than and including the start_date.  If 
   * End date is specified, it can be used to purge a range of versions instead. Date should be in 
   * DATE_RFC822 format
   *
   * @param string $start_date
   * @param string $end_date
   * @return boolean $valid
   */
  public function purgeVersions($start_date, $end_date = NULL) {
      module_load_include('inc', 'fedora_repository', 'api/fedora_item');
      $fedora_item = new Fedora_Item($this->pid);
      return $fedora_item->purge_datastream( $this->dsid, $start_date, $end_date);
  }
  
  /**
   * Gets the history of the datastream from fedora.
   * Returns false on failure.
   *
   * @return string[] $ret
   */  
  public function getHistory() {
      module_load_include('inc', 'fedora_repository', 'api/fedora_item');
      $fedora_item = new Fedora_Item($this->pid);
      $history = $fedora_item->get_datastream_history($this->dsid);
      
      $ret = FALSE;
      if ($history !== FALSE) {
        $ret = array();
        foreach ($history as $version) {
            if ($version->versionID !== NULL) $ret[] = array('versionID' => $version->versionID, 'createDate' => $version->createDate);  
        }
      }
      return $ret;
  }
  
  /**
   * Attempts to convert from the old XML schema to the new by 
   * traversing the XML DOM and building a new DOM.  When done
   * $this->xml is replaced by the newly created DOM..
   *
   * @return void
   */
  abstract protected function convertFromOldSchema();
  
}