/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      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.springframework.oxm.support;

import java.io.IOException;

import javax.xml.transform.Source;
import javax.xml.transform.sax.SAXResult;
import javax.xml.transform.sax.SAXSource;

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.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.ext.LexicalHandler;

import org.springframework.lang.Nullable;
import org.springframework.oxm.Marshaller;
import org.springframework.util.Assert;

Source implementation that uses a Marshaller.Can be constructed with a Marshaller and an object to be marshalled. 
Even though MarshallingSource extends from SAXSource, calling the methods of SAXSource is not supported. In general, the only supported operation on this class is to use the XMLReader obtained via SAXSource.getXMLReader() to parse the input source obtained via SAXSource.getInputSource(). Calling setXMLReader(XMLReader) or setInputSource(InputSource) will result in UnsupportedOperationExceptions. 
Author:
Arjen Poutsma
See Also:
Transformer
Since:
3.0/**
 * {@link Source} implementation that uses a {@link Marshaller}.Can be constructed with a
 * {@code Marshaller} and an object to be marshalled.
 *
 * <p>Even though {@code MarshallingSource} extends from {@code SAXSource}, calling the methods of
 * {@code SAXSource} is <strong>not supported</strong>. In general, the only supported operation on this class is
 * to use the {@code XMLReader} obtained via {@link #getXMLReader()} to parse the input source obtained via {@link
 * #getInputSource()}. Calling {@link #setXMLReader(XMLReader)} or {@link #setInputSource(InputSource)} will result in
 * {@code UnsupportedOperationException}s.
 *
 * @author Arjen Poutsma
 * @since 3.0
 * @see javax.xml.transform.Transformer
 */
public class MarshallingSource extends SAXSource {

	private final Marshaller marshaller;

	private final Object content;


	
Create a new MarshallingSource with the given marshaller and content. 
Params:
marshaller – the marshaller to use
content – the object to be marshalled/**
	 * Create a new {@code MarshallingSource} with the given marshaller and content.
	 * @param marshaller the marshaller to use
	 * @param content the object to be marshalled
	 */
	public MarshallingSource(Marshaller marshaller, Object content) {
		super(new MarshallingXMLReader(marshaller, content), new InputSource());
		Assert.notNull(marshaller, "'marshaller' must not be null");
		Assert.notNull(content, "'content' must not be null");
		this.marshaller = marshaller;
		this.content = content;
	}


	
Return the Marshaller used by this MarshallingSource. /**
	 * Return the {@code Marshaller} used by this {@code MarshallingSource}.
	 */
	public Marshaller getMarshaller() {
		return this.marshaller;
	}

	
Return the object to be marshalled.
/**
	 * Return the object to be marshalled.
	 */
	public Object getContent() {
		return this.content;
	}

	
Throws a UnsupportedOperationException. /**
	 * Throws a {@code UnsupportedOperationException}.
	 */
	@Override
	public void setInputSource(InputSource inputSource) {
		throw new UnsupportedOperationException("setInputSource is not supported");
	}

	
Throws a UnsupportedOperationException. /**
	 * Throws a {@code UnsupportedOperationException}.
	 */
	@Override
	public void setXMLReader(XMLReader reader) {
		throw new UnsupportedOperationException("setXMLReader is not supported");
	}


	private static final class MarshallingXMLReader implements XMLReader {

		private final Marshaller marshaller;

		private final Object content;

		@Nullable
		private DTDHandler dtdHandler;

		@Nullable
		private ContentHandler contentHandler;

		@Nullable
		private EntityResolver entityResolver;

		@Nullable
		private ErrorHandler errorHandler;

		@Nullable
		private LexicalHandler lexicalHandler;

		private MarshallingXMLReader(Marshaller marshaller, Object content) {
			Assert.notNull(marshaller, "'marshaller' must not be null");
			Assert.notNull(content, "'content' must not be null");
			this.marshaller = marshaller;
			this.content = content;
		}

		@Override
		public void setContentHandler(@Nullable ContentHandler contentHandler) {
			this.contentHandler = contentHandler;
		}

		@Override
		@Nullable
		public ContentHandler getContentHandler() {
			return this.contentHandler;
		}

		@Override
		public void setDTDHandler(@Nullable DTDHandler dtdHandler) {
			this.dtdHandler = dtdHandler;
		}

		@Override
		@Nullable
		public DTDHandler getDTDHandler() {
			return this.dtdHandler;
		}

		@Override
		public void setEntityResolver(@Nullable EntityResolver entityResolver) {
			this.entityResolver = entityResolver;
		}

		@Override
		@Nullable
		public EntityResolver getEntityResolver() {
			return this.entityResolver;
		}

		@Override
		public void setErrorHandler(@Nullable ErrorHandler errorHandler) {
			this.errorHandler = errorHandler;
		}

		@Override
		@Nullable
		public ErrorHandler getErrorHandler() {
			return this.errorHandler;
		}

		@Nullable
		protected LexicalHandler getLexicalHandler() {
			return this.lexicalHandler;
		}

		@Override
		public boolean getFeature(String name) throws SAXNotRecognizedException {
			throw new SAXNotRecognizedException(name);
		}

		@Override
		public void setFeature(String name, boolean value) throws SAXNotRecognizedException {
			throw new SAXNotRecognizedException(name);
		}

		@Override
		@Nullable
		public Object getProperty(String name) throws SAXNotRecognizedException {
			if ("http://xml.org/sax/properties/lexical-handler".equals(name)) {
				return this.lexicalHandler;
			}
			else {
				throw new SAXNotRecognizedException(name);
			}
		}

		@Override
		public void setProperty(String name, Object value) throws SAXNotRecognizedException {
			if ("http://xml.org/sax/properties/lexical-handler".equals(name)) {
				this.lexicalHandler = (LexicalHandler) value;
			}
			else {
				throw new SAXNotRecognizedException(name);
			}
		}

		@Override
		public void parse(InputSource input) throws SAXException {
			parse();
		}

		@Override
		public void parse(String systemId) throws SAXException {
			parse();
		}

		private void parse() throws SAXException {
			SAXResult result = new SAXResult(getContentHandler());
			result.setLexicalHandler(getLexicalHandler());
			try {
				this.marshaller.marshal(this.content, result);
			}
			catch (IOException ex) {
				SAXParseException saxException = new SAXParseException(ex.getMessage(), null, null, -1, -1, ex);
				ErrorHandler errorHandler = getErrorHandler();
				if (errorHandler != null) {
					errorHandler.fatalError(saxException);
				}
				else {
					throw saxException;
				}
			}
		}
	}

}