/**

  * 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 java.util.Arrays;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 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 {

 	public static final String PARAMETER_TYPED_PARAMETERS = "typed-parameters";

 	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();

 		final List<String> actionData = getActionContext().getActionData();

 		if (actionData.size() < 1) {

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

 		} else {

 			boolean typedParameters = Boolean.parseBoolean(actionContext.getActionProperties().getProperty(PARAMETER_TYPED_PARAMETERS));

 			Map<String, Object> xpathParameters = new HashMap<>();

 			for (int i = 1; i < actionData.size(); i++) {

 				String parameterName = actionData.get(i++);

 				String parameterType = typedParameters ? actionData.get(i++) : PARAMETER_TYPE.STRING.name();

 				Object parameterValue = parseParameterValue(parameterType, actionData.get(i));

 				xpathParameters.put(parameterName, parameterValue);

 			}

 			xpath.setXPathVariableResolver(new PropertiesVariableResolver(xpathParameters));

 			expressionString = actionData.get(0);

 			try {

 				xpathExpression = xpath.compile(expressionString);

 			} catch (XPathExpressionException e) {

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

 			}

 		}

 	}

 	private enum PARAMETER_TYPE {

 		// TODO: wait for Java 8 widespread and rewrite with lambdas :-)

 		STRING {

 					@Override

 					public Object parse(String value) {

 						return value;

 					}

 				},

 		BOOLEAN {

 					@Override

 					public Object parse(String value) {

 						return Boolean.valueOf(value);

 					}

 				},

 		INTEGER {

 					@Override

 					public Object parse(String value) {

 						return Integer.parseInt(value);

 					}

 				},

 		LONG {

 					@Override

 					public Object parse(String value) {

 						return Long.parseLong(value);

 					}

 				},

 		DOUBLE {

 					@Override

 					public Object parse(String value) {

 						return Double.parseDouble(value);

 					}

 				};

 		public abstract Object parse(String value);

 	}

 	private static Object parseParameterValue(String type, String value) throws OutputActionException {

 		try {

 			PARAMETER_TYPE parameterType = PARAMETER_TYPE.valueOf(type.toUpperCase());

 			try {

 				return parameterType.parse(value);

 			} catch (IllegalArgumentException e) {

 				throw new OutputActionException("Unable to parse value: „" + value + "“ as " + parameterType.name());

 			}

 		} catch (IllegalArgumentException e) {

 			throw new OutputActionException(

 					"Invalid XPath parameter type: „" + type

 					+ "“. Possible values are: " + Arrays.toString(PARAMETER_TYPE.values())

 					+ " and are case insensitive.",

 					e);

 		}

 	}

 	@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);

 		}

 	}

 }