/**

  * Alt2XML

  * Copyright © 2014 František Kučera (frantovo.cz)

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 3 of the License, or

  * (at your option) any later version.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. If not, see <http://www.gnu.org/licenses/>.

  */

 package cz.frantovo.alt2xml.out.xpath;

 import cz.frantovo.alt2xml.out.AbstractDOMAction;

 import cz.frantovo.alt2xml.out.ActionContext;

 import cz.frantovo.alt2xml.out.OutputActionException;

 import java.io.PrintWriter;

 import javax.xml.transform.dom.DOMResult;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathExpression;

 import javax.xml.xpath.XPathExpressionException;

 import javax.xml.xpath.XPathFactory;

 /**

  *

  * @author Ing. František Kučera (frantovo.cz)

  */

 public class XPathAction extends AbstractDOMAction {

 	private final XPathFactory xpathFactory;

 	private final XPath xpath;

 	private final String expressionString;

 	private final XPathExpression xpathExpression;

 	public XPathAction(ActionContext actionContext) throws OutputActionException {

 		super(actionContext);

 		xpathFactory = XPathFactory.newInstance();

 		xpath = xpathFactory.newXPath();

 		if (!actionContext.getActionProperties().isEmpty()) {

 			xpath.setXPathVariableResolver(new PropertiesVariableResolver(actionContext.getActionProperties()));

 		}

 		if (getActionContext().getActionData().size() == 1) {

 			expressionString = getActionContext().getActionData().get(0);

 			try {

 				xpathExpression = xpath.compile(expressionString);

 			} catch (XPathExpressionException e) {

 				throw new OutputActionException("Unable to compile XPath: " + expressionString, e);

 			}

 		} else {

 			throw new OutputActionException("Please specify the XPath expression as action data");

 		}

 	}

 	@Override

 	public void run(DOMResult domResult) throws OutputActionException {

 		try {

 			String result = xpathExpression.evaluate(domResult.getNode());

 			try (PrintWriter out = new PrintWriter(getActionContext().getOutputStream())) {

 				out.println(result);

 			}

 		} catch (XPathExpressionException e) {

 			throw new OutputActionException("Unable to evaluate XPath: " + xpathExpression, e);

 		}

 	}

 }