/*
    * 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.io.IOException;
  import java.util.Objects;
  
  import org.xml.sax.ContentHandler;
  import org.xml.sax.DTDHandler;
  import org.xml.sax.EntityResolver;
  import org.xml.sax.ErrorHandler;
  import org.xml.sax.InputSource;
  import org.xml.sax.SAXException;
  import org.xml.sax.SAXNotRecognizedException;
  import org.xml.sax.SAXNotSupportedException;
  import org.xml.sax.XMLReader;
  
  /**
   * {@link XMLReader} wrapper that keeps a {@link FallbackIgnoreEntityResolver2} floor as the reader's entity resolver, non-overridable by the caller.
   *
   * <p>The floor is installed once and stays the reader's entity resolver for the wrapper's lifetime; {@link #setEntityResolver(EntityResolver)} routes the
   * caller's resolver through {@link FallbackIgnoreEntityResolver2#setDelegate} instead of replacing it. This includes the {@code DefaultHandler} that
   * {@link javax.xml.parsers.SAXParser#parse(org.xml.sax.InputSource, org.xml.sax.helpers.DefaultHandler) SAXParser.parse(source, handler)} installs as the
   * reader's entity resolver, which would otherwise silently replace the floor. {@link #getEntityResolver()} reports the caller's resolver unwrapped.</p>
   *
   * <p>Every other method forwards to the wrapped delegate; subclasses (e.g. {@code SecureExpatXMLReader}) add per-implementation fixups on top of the floor.</p>
   */
  class SecureXMLReader implements XMLReader {
  
      private final XMLReader delegate;
  
      private final FallbackIgnoreEntityResolver2 floor;
  
      /**
       * Constructs a new instance.
       *
       * @param delegate The delegate to wrap; must not be {@code null}.
       * @throws NullPointerException Thrown if {@code delegate} is {@code null}.
       */
      SecureXMLReader(final XMLReader delegate) {
          this.delegate = Objects.requireNonNull(delegate, "delegate");
          this.floor = new FallbackIgnoreEntityResolver2(null);
          delegate.setEntityResolver(floor);
      }
  
      @Override
      public ContentHandler getContentHandler() {
          return delegate.getContentHandler();
      }
  
      /**
       * Gets the wrapped reader, so tests can observe which parser implementation a rewrite picked.
       *
       * @return The wrapped reader.
       */
      XMLReader getDelegate() {
          return delegate;
      }
  
      @Override
      public DTDHandler getDTDHandler() {
          return delegate.getDTDHandler();
      }
  
      @Override
      public EntityResolver getEntityResolver() {
          return floor.getDelegate();
      }
  
      @Override
      public ErrorHandler getErrorHandler() {
          return delegate.getErrorHandler();
      }
  
      @Override
      public boolean getFeature(final String name) throws SAXNotRecognizedException, SAXNotSupportedException {
          return delegate.getFeature(name);
      }
  
      @Override
      public Object getProperty(final String name) throws SAXNotRecognizedException, SAXNotSupportedException {
          return delegate.getProperty(name);
      }
  
     @Override
     public void parse(final InputSource input) throws IOException, SAXException {
         delegate.parse(input);
     }
 
     @Override
     public void parse(final String systemId) throws IOException, SAXException {
         delegate.parse(systemId);
     }
 
     /**
      * Re-installs the floor as the wrapped reader's entity resolver and drops any caller-supplied resolver, restoring the just-created state.
      */
     void restoreFloor() {
         floor.setDelegate(null);
         delegate.setEntityResolver(floor);
     }
 
     @Override
     public void setContentHandler(final ContentHandler handler) {
         delegate.setContentHandler(handler);
     }
 
     @Override
     public void setDTDHandler(final DTDHandler handler) {
         delegate.setDTDHandler(handler);
     }
 
     @Override
     public void setEntityResolver(final EntityResolver resolver) {
         floor.setDelegate(resolver);
     }
 
     @Override
     public void setErrorHandler(final ErrorHandler handler) {
         delegate.setErrorHandler(handler);
     }
 
     @Override
     public void setFeature(final String name, final boolean value) throws SAXNotRecognizedException, SAXNotSupportedException {
         delegate.setFeature(name, value);
     }
 
     @Override
     public void setProperty(final String name, final Object value) throws SAXNotRecognizedException, SAXNotSupportedException {
         delegate.setProperty(name, value);
     }
 
 }