/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You 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
    *
    *      https://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.xml.secure;
  
  import java.util.Objects;
  import java.util.function.Supplier;
  
  import javax.xml.transform.Source;
  import javax.xml.transform.Templates;
  import javax.xml.transform.URIResolver;
  import javax.xml.transform.sax.TemplatesHandler;
  
  import org.xml.sax.Attributes;
  import org.xml.sax.Locator;
  import org.xml.sax.SAXException;
  
  /**
   * {@link TemplatesHandler} wrapper whose only purpose is to return a {@link SecureTemplates} from {@link TemplatesHandler#getTemplates()}.
   *
   * <p>The handler itself only compiles: the caller drives the stylesheet's SAX events, and {@code xsl:include}/{@code xsl:import} hrefs already resolve through
   * the delegate factory's resolver, which is the secure floor. What the raw handler lacks is the runtime side: the {@link Templates} it compiles produce
   * Transformers without a {@link URIResolver} floor. Wrapping {@code getTemplates()} closes that, exactly as
   * {@link javax.xml.transform.TransformerFactory#newTemplates newTemplates} does.</p>
   */
  final class SecureTemplatesHandler implements TemplatesHandler {
  
      private final TemplatesHandler delegate;
  
      /**
       * Compile-time URIResolver snapshot, restored onto Transformers produced from the compiled Templates.
       */
      private final URIResolver uriResolver;
  
      /**
       * Empty-{@link Source} supplier for the produced Templates' floor; {@code null} means the default empty DOM.
       */
      private final Supplier<Source> emptySource;
  
      /**
       * Snapshot of the factory's {@value SecureSAXParserFactory#OVERRIDE_DEFAULT_PARSER} outcome, carried onto the produced Templates.
       */
      private final boolean overrideDefaultParser;
  
      /**
       * Constructs a new instance.
       *
       * @param delegate the delegate to wrap; must not be {@code null}.
       * @param uriResolver the compile-time URIResolver snapshot to restore onto Transformers produced from the compiled Templates; may be {@code null}.
       * @param emptySource the empty-{@link Source} supplier for the produced Templates; may be {@code null} for the default empty DOM document.
       * @param overrideDefaultParser whether the produced Templates' source rewrites should use the pluggable parser lookup instead of the platform's built-in parser.
       * @throws NullPointerException if {@code delegate} is {@code null}.
       */
      SecureTemplatesHandler(final TemplatesHandler delegate, final URIResolver uriResolver, final Supplier<Source> emptySource,
              final boolean overrideDefaultParser) {
          this.delegate = Objects.requireNonNull(delegate, "delegate");
          this.uriResolver = uriResolver;
          this.emptySource = emptySource;
          this.overrideDefaultParser = overrideDefaultParser;
      }
  
      @Override
      public void characters(final char[] ch, final int start, final int length) throws SAXException {
          delegate.characters(ch, start, length);
      }
  
      @Override
      public void endDocument() throws SAXException {
          delegate.endDocument();
      }
  
      @Override
      public void endElement(final String uri, final String localName, final String qName) throws SAXException {
          delegate.endElement(uri, localName, qName);
      }
  
      @Override
      public void endPrefixMapping(final String prefix) throws SAXException {
          delegate.endPrefixMapping(prefix);
      }
  
      @Override
      public String getSystemId() {
          return delegate.getSystemId();
      }
 
     @Override
     public Templates getTemplates() {
         // Null before the stylesheet's endDocument (and on a failed compile in some implementations).
         final Templates templates = delegate.getTemplates();
         return templates == null ? null : new SecureTemplates(templates, uriResolver, emptySource, overrideDefaultParser);
     }
 
     @Override
     public void ignorableWhitespace(final char[] ch, final int start, final int length) throws SAXException {
         delegate.ignorableWhitespace(ch, start, length);
     }
 
     @Override
     public void processingInstruction(final String target, final String data) throws SAXException {
         delegate.processingInstruction(target, data);
     }
 
     @Override
     public void setDocumentLocator(final Locator locator) {
         delegate.setDocumentLocator(locator);
     }
 
     @Override
     public void setSystemId(final String systemID) {
         delegate.setSystemId(systemID);
     }
 
     @Override
     public void skippedEntity(final String name) throws SAXException {
         delegate.skippedEntity(name);
     }
 
 
     @Override
     public void startDocument() throws SAXException {
         delegate.startDocument();
     }
 
     @Override
     public void startElement(final String uri, final String localName, final String qName, final Attributes atts) throws SAXException {
         delegate.startElement(uri, localName, qName, atts);
     }
 
     @Override
     public void startPrefixMapping(final String prefix, final String uri) throws SAXException {
         delegate.startPrefixMapping(prefix, uri);
     }
 }