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/**
 * Copyright (c) 2011-2016, Qulice.com
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met: 1) Redistributions of source code must retain the above
 * copyright notice, this list of conditions and the following
 * disclaimer. 2) Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided
 * with the distribution. 3) Neither the name of the Qulice.com nor
 * the names of its contributors may be used to endorse or promote
 * products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.qulice.xml;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

/**
 * Prettifies XML files.
 *
 * @author Krzysztof Krason ([email protected])
 * @version $Id$
 * @since 0.9
 */
public final class Prettifier {

    /**
     * Input XML.
     */
    private final String xml;

    /**
     * Constructor.
     *
     * @param xml Input XML.
     */
    public Prettifier(final String xml) {
        this.xml = xml;
    }

    /**
     * Prettify XML by indenting it.
     *
     * @return Formatted XML.
     * @checkstyle MultipleStringLiterals (9 lines)
     */
    public String prettify() {
        try (
            final Writer writer = new StringWriter();
            final Reader reader = new StringReader(this.xml)
        ) {
            final Transformer transformer = TransformerFactory
                .newInstance().newTransformer();
            transformer.setOutputProperty(OutputKeys.METHOD, "xml");
            transformer.setOutputProperty(OutputKeys.INDENT, "yes");
            transformer.setOutputProperty(
                OutputKeys.OMIT_XML_DECLARATION, "no"
            );
            transformer.setOutputProperty(
                "{http://xml.apache.org/xslt}indent-amount", "2"
            );
            final StreamResult result = new StreamResult(writer);
            transformer.transform(new StreamSource(reader), result);
            return String.format(
                "%s%n",
                result.getWriter().toString()
                    .replaceFirst("\\?><", "?>\n<")
                    .replaceFirst("-->", "-->\n")
                    .replaceFirst("\\?>