/*
    * Copyright 2002,2004 The Apache Software Foundation.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.jelly.tags.validate;
  
  import org.apache.commons.jelly.JellyTagException;
  import org.apache.commons.jelly.MissingAttributeException;
  import org.apache.commons.jelly.TagSupport;
  import org.apache.commons.jelly.XMLOutput;
  import org.iso_relax.verifier.Verifier;
  import org.iso_relax.verifier.VerifierFilter;
  import org.iso_relax.verifier.VerifierHandler;
  import org.xml.sax.ContentHandler;
  import org.xml.sax.ErrorHandler;
  import org.xml.sax.SAXException;
  import org.xml.sax.SAXParseException;
  import org.xml.sax.helpers.AttributesImpl;
  
  /***
   * This tag validates its body using a schema Verifier which can
   * validate against DTDs, XML Schema, RelaxNG, Relax or TREX.
   * Any JARV compliant Verifier could be used.
   * The error messages are output as XML events so that they can be styled by the parent tag.
   *
   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
   * @version $Revision: 155420 $
   */
  public class ValidateTag extends TagSupport {
  
      /*** The verifier that this tag will use */
      private Verifier verifier;
  
      /*** The SAX ErrorHandler */
      private ErrorHandler errorHandler;
  
      /*** The boolean flag for whether the XML is valid */
      private String var;
  
      // Tag interface
      //-------------------------------------------------------------------------
      public void doTag(final XMLOutput output) throws MissingAttributeException, JellyTagException {
          if ( verifier == null ) {
              throw new MissingAttributeException("verifier");
          }
          boolean valid = false;
  
          // evaluate the body using the current Verifier
          if ( errorHandler != null ) {
  
              try {
                  // we are redirecting errors to another handler
                  // so just filter the body
                  VerifierFilter filter = verifier.getVerifierFilter();
  
                  // now install the current output in the filter chain...
                  // ####
  
                  ContentHandler handler = filter.getContentHandler();
                  handler.startDocument();
                  invokeBody( new XMLOutput( handler ) );
                  handler.endDocument();
                  valid = filter.isValid();
              }
              catch (SAXException e) {
                  throw new JellyTagException(e);
              }
          }
          else {
              // outputting the errors to the current output
              verifier.setErrorHandler(
                  new ErrorHandler() {
                      public void error(SAXParseException exception) throws SAXException {
                          outputException(output, "error", exception);
                      }
  
                      public void fatalError(SAXParseException exception) throws SAXException {
                          outputException(output, "fatalError", exception);
                      }
  
                      public void warning(SAXParseException exception) throws SAXException {
                          outputException(output, "warning", exception);
                      }
                  }
              );
  
              try {
                  VerifierHandler handler = verifier.getVerifierHandler();
                 handler.startDocument();
                 invokeBody( new XMLOutput( handler ) );
                 handler.endDocument();
                 valid = handler.isValid();
             }
             catch (SAXException e) {
                 throw new JellyTagException(e);
             }
         }
         handleValid(valid);
     }
 
     // Properties
     //-------------------------------------------------------------------------
 
     /***
      * Sets the schema Verifier that this tag will use to verify its body
      *
      * @jelly:required
      */
     public void setVerifier(Verifier verifier) {
         this.verifier = verifier;
     }
 
     /***
      * @return the ErrorHandler used when validating
      */
     public ErrorHandler getErrorHandler() {
         return errorHandler;
     }
 
     /***
      * Sets the SAX ErrorHandler which is used to capture
      * XML validation events.
      * If an ErrorHandler is specified
      * then this tag will output its body and redirect all error messages
      * to the ErrorHandler.
      * If no ErrorHandler is specified then this tag will just output the
      * error messages as XML events
      *
      * @jelly:optional
      */
     public void setErrorHandler(ErrorHandler errorHandler) {
         this.errorHandler = errorHandler;
     }
 
     /***
      * Sets the name of the variable that will contain a boolean flag for whether or
      * not the XML is valid.
      *
      * @jelly:optional
      */
     public void setVar(String var) {
         this.var = var;
     }
 
     // Implementation methods
     //-------------------------------------------------------------------------
 
     /***
      * Processes whether or not the document is valid.
      * Derived classes can overload this method to do different things, such
      * as to throw assertion exceptions etc.
      */
     protected void handleValid(boolean valid) {
         if (var != null ) {
             Boolean value = (valid) ? Boolean.TRUE : Boolean.FALSE;
             context.setVariable(var, value);
         }
     }
 
     /***
      * Outputs the given validation exception as XML to the output
      */
     protected void outputException(XMLOutput output, String name, SAXParseException e) throws SAXException {
         AttributesImpl attributes = new AttributesImpl();
         String uri = "";
         String type = "CDATA";
         attributes.addAttribute( uri, "column", "column", type, Integer.toString( e.getColumnNumber() ) );
         attributes.addAttribute( uri, "line", "line", type, Integer.toString( e.getLineNumber() ) );
 
         String publicID = e.getPublicId();
         if ( publicID != null && publicID.length() > 0 ) {
             attributes.addAttribute( uri, "publicID", "publicID", type, publicID );
         }
         String systemID = e.getSystemId();
         if ( systemID != null && systemID.length() > 0 ) {
             attributes.addAttribute( uri, "systemID", "systemID", type, systemID );
         }
 
         output.startElement( uri, name, name, attributes );
         output.write( e.getMessage() );
         output.endElement( uri, name, name );
     }
 
 
 }