/*
    * 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
    *
    *      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.juneau;
  
  import static javax.xml.stream.XMLStreamConstants.*;
  
  import java.io.*;
  import java.lang.reflect.*;
  import java.util.*;
  
  import javax.xml.stream.*;
  
  import org.apache.juneau.parser.*;
  import org.apache.juneau.xml.*;
  
  /**
   * Used to validate that the syntax of XML documents are valid.
   *
   * <ul class='spaced-list'>
   * 	<li class='note'>This class is thread safe and reusable.
   * </ul>
   */
  @SuppressWarnings("unchecked")
  public class XmlValidatorParser extends XmlParser {
  
  	//-----------------------------------------------------------------------------------------------------------------
  	// Instance
  	//-----------------------------------------------------------------------------------------------------------------
  
  	public XmlValidatorParser() {
  		super(create());
  	}
  
  	@Override /* Context */
  	public XmlParserSession.Builder createSession() {
  		return new XmlParserSession.Builder(XmlParser.DEFAULT) {
  			@Override
  			public XmlParserSession build() {
  				return new XmlParserSession(this) {
  
  					@Override
  					protected <T> T doParse(ParserPipe pipe, ClassMeta<T> type) throws IOException, ParseException, ExecutableException {
  						try {
  							return type.cast(validate(pipe.getReader()));
  						} catch (Exception e) {
  							throw new ParseException(e);
  						}
  					}
  
  					@Override /* ReaderParser */
  					protected <K,V> Map<K,V> doParseIntoMap(ParserPipe pipe, Map<K,V> m, Type keyType, Type valueType) throws Exception {
  						return (Map<K,V>)validate(pipe.getReader());
  					}
  
  					@Override /* ReaderParser */
  					protected <E> Collection<E> doParseIntoCollection(ParserPipe pipe, Collection<E> c, Type elementType) throws Exception {
  						return (Collection<E>)validate(pipe.getReader());
  					}
  				};
  			}
  		};
  	}
  
  	public <T> T validate(Reader r) throws Exception {
  		var sr = getStaxReader(r);
  		while (sr.next() != END_DOCUMENT) {/*no-op*/}
  		return null;
  	}
  
  	protected XMLStreamReader getStaxReader(Reader in) throws Exception {
  		var factory = XMLInputFactory.newInstance();
  		factory.setProperty("javax.xml.stream.isNamespaceAware", false);
  		var parser = factory.createXMLStreamReader(in);
  		parser.nextTag();
  		return parser;
  	}
  }