<?php
/**
 * TXmlTransform class file
 *
 * @author Knut Urdalen <knut.urdalen@gmail.com>
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com
 * @copyright Copyright &copy; 2005-2014 PradoSoft
 * @license http://www.pradosoft.com/license/
 * @package Prado\Web\UI\WebControls
 */

namespace Prado\Web\UI\WebControls;
use DOMDocument;
use Prado\Collections\TAttributeCollection;
use Prado\Exceptions\TConfigurationException;
use Prado\Exceptions\TInvalidDataValueException;
use Prado\IO\TTextWriter;
use Prado\Prado;
use XSLTProcessor;

/**
 * TXmlTransform class
 *
 * TXmlTransform uses the PHP's XSL extension to perform
 * {@link http://www.w3.org/TR/xslt XSL transformations} using the
 * {@link http://xmlsoft.org/XSLT/ libxslt library}.
 *
 * To associate an XML style sheet with TXmlTransform set the
 * {@link setTransformPath TransformPath} property to the namespace or path to the style sheet
 * or set the {@link setTransformContent TransformContent} property to the XML style sheet
 * data as a string.
 *
 * To associate the XML data to be transformed set the {@link setDocumentPath DocumentPath}
 * property to the namespace or path to the XML document or set the
 * {@link setDocumentContent DocumentContent} property to the XML data as a string.
 *
 * To add additional parameters to the transformation process you can use the {@link getParameters Parameters}
 * property.
 *
 * @author Knut Urdalen <knut.urdalen@gmail.com>
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @package Prado\Web\UI\WebControls
 * @since 3.1
 */
class TXmlTransform extends \Prado\Web\UI\TControl {

  const EXT_XML_FILE = '.xml';
  const EXT_XSL_FILE = '.xsl';

  /**
   * Constructor
   *
   * Initializes the TXmlTransform object and ensure that the XSL extension is available
   * @throws TConfigurationException If XSL extension is not available
   */
  public function __construct() {
    if(!class_exists('XSLTProcessor', false)) {
      throw new TConfigurationException('xmltransform_xslextension_required');
    }
  }

  /**
   * @return string The path to the XML style sheet.
   */
  public function getTransformPath() {
    return $this->getViewState('TransformPath', '');
  }

  /**
   * @param string The path to the XML style sheet.  It must be in namespace format.
   */
  public function setTransformPath($value) {
    if(!is_file($value)) {
      $value = Prado::getPathOfNamespace($value, self::EXT_XSL_FILE);
      if($value === null) {
	throw new TInvalidDataValueException('xmltransform_transformpath_invalid', $value);
      }
    }
    $this->setViewState('TransformPath', $value, '');
  }

  /**
   * @return string XML style sheet as string
   */
  public function getTransformContent() {
    return $this->getViewState('TransformContent', '');
  }

  /**
   * @param string $value XML style sheet as string
   */
  public function setTransformContent($value) {
    $this->setViewState('TransformContent', $value, '');
  }

  /**
   * @return string The path to the XML document. It must be in namespace format.
   */
  public function getDocumentPath() {
    return $this->getViewState('DocumentPath', '');
  }

  /**
   * @param string Namespace or path to XML document
   * @throws TInvalidDataValueException
   */
  public function setDocumentPath($value) {
    if(!is_file($value)) {
      $value = Prado::getPathOfNamespace($value, self::EXT_XML_FILE);
      if($value === null) {
	throw new TInvalidDataValueException('xmltransform_documentpath_invalid', $value);
      }
    }
    $this->setViewState('DocumentPath', $value, '');
  }

  /**
   * @return string XML data
   */
  public function getDocumentContent() {
    return $this->getViewState('DocumentContent', '');
  }

  /**
   * @param string $value XML data. If not empty, it takes precedence over {@link setDocumentPath DocumentPath}.
   */
  public function setDocumentContent($value) {
    $this->setViewState('DocumentContent', $value, '');
  }

  /**
   * Returns the list of parameters to be applied to the transform.
   * @return TAttributeCollection the list of custom parameters
   */
  public function getParameters() {
    if($params = $this->getViewState('Parameters',null)) {
      return $params;
    } else {
      $params = new TAttributeCollection();
      $this->setViewState('Parameters', $params, null);
      return $params;
    }
  }

  private function getTransformXmlDocument() {
    if(($content = $this->getTransformContent()) !== '') {
      $document = new DOMDocument();
      $document->loadXML($content);
      return $document;
    } else if(($path = $this->getTransformPath()) !== '') {
      $document = new DOMDocument();
      $document->load($path);
      return $document;
    } else {
      throw new TConfigurationException('xmltransform_transform_required');
    }
  }

  private function getSourceXmlDocument() {
    if(($content = $this->getDocumentContent()) !== '') {
      $document = new DOMDocument();
      $document->loadXML($content);
      return $document;
    } else if(($path = $this->getDocumentPath()) !== '') {
      $document = new DOMDocument();
      $document->load($path);
      return $document;
    } else {
      return null;
    }
  }

  /**
   * Performs XSL transformation and render the output.
   * @param THtmlWriter The writer used for the rendering purpose
   */
  public function render($writer) {
    if(($document=$this->getSourceXmlDocument()) === null) {
	  $htmlWriter = Prado::createComponent($this->GetResponse()->getHtmlWriterType(), new TTextWriter());
	  parent::render($htmlWriter);
      $document = new DOMDocument();
      $document->loadXML($htmlWriter->flush());
    }
    $stylesheet = $this->getTransformXmlDocument();

    // Perform XSL transformation
    $xslt = new XSLTProcessor();
    $xslt->importStyleSheet($stylesheet);

    // Check for parameters
    $parameters = $this->getParameters();
    foreach($parameters as $name => $value) {
      $xslt->setParameter('', $name, $value);
    }
    $output = $xslt->transformToXML($document);

    // Write output
    $writer->write($output);
  }
}