/**

  * 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, version 3 of the License.

  *

  * 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.io.StringWriter;

 import java.util.Arrays;

 import java.util.HashMap;

 import java.util.List;

 import java.util.Map;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import javax.xml.transform.OutputKeys;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerConfigurationException;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.TransformerFactoryConfigurationError;

 import javax.xml.transform.dom.DOMResult;

 import javax.xml.transform.dom.DOMSource;

 import javax.xml.transform.stream.StreamResult;

 import javax.xml.xpath.XPath;

 import javax.xml.xpath.XPathConstants;

 import javax.xml.xpath.XPathExpression;

 import javax.xml.xpath.XPathExpressionException;

 import javax.xml.xpath.XPathFactory;

 import javax.xml.xpath.XPathVariableResolver;

 import org.w3c.dom.Attr;

 import org.w3c.dom.Element;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 /**

  *

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

  */

 public class XPathAction extends AbstractDOMAction {

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

 	public static final String PARAMETER_LINE_BREAK = "line-break";

 	public static final String PARAMETER_ENVIRONMENT_VARIABLES = "environment-variables";

 	public static final String PARAMETER_NODE_SET = "node-set";

 	private static final Logger log = Logger.getLogger(XPathAction.class.getName());

 	private final boolean typedParameters;

 	private final boolean lineBreak;

 	private final boolean environmentVariables;

 	private final boolean nodeSet;

 	private final TransformerFactory transformerFactory;

 	private final Transformer copyTransformer;

 	private final XPathFactory xpathFactory;

 	private final XPath xpath;

 	private final String expressionString;

 	public XPathAction(ActionContext actionContext) throws OutputActionException {

 		super(actionContext);

 		xpathFactory = XPathFactory.newInstance();

 		xpath = xpathFactory.newXPath();

 		try {

 			transformerFactory = TransformerFactory.newInstance();

 			copyTransformer = transformerFactory.newTransformer();

 			copyTransformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");

 		} catch (TransformerConfigurationException | TransformerFactoryConfigurationError e) {

 			throw new OutputActionException("Unable to initialize XSLT copying transformer", e);

 		}

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

 		if (actionData.size() < 1) {

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

 		} else {

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

 			lineBreak = Boolean.parseBoolean(actionContext.getActionProperties().getProperty(PARAMETER_LINE_BREAK, Boolean.TRUE.toString()));

 			environmentVariables = Boolean.parseBoolean(actionContext.getActionProperties().getProperty(PARAMETER_ENVIRONMENT_VARIABLES, Boolean.FALSE.toString()));

 			nodeSet = Boolean.parseBoolean(actionContext.getActionProperties().getProperty(PARAMETER_NODE_SET, Boolean.FALSE.toString()));

 			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);

 			}

 			XPathVariableResolver cliVariableResolver = new PropertiesVariableResolver(xpathParameters);

 			XPathVariableResolver variableResolver = environmentVariables ? new CompoundVariableResolver(cliVariableResolver, new EnvironmentVariableResolver()) : cliVariableResolver;

 			xpath.setXPathVariableResolver(variableResolver);

 			expressionString = actionData.get(0);

 		}

 	}

 	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);

 		}

 	}

 	private String nodeToString(Node node) throws OutputActionException {

 		try {

 			StringWriter w = new StringWriter();

 			copyTransformer.transform(new DOMSource(node), new StreamResult(w));

 			return w.toString();

 		} catch (TransformerException e) {

 			throw new OutputActionException("Unable to convert node to string", e);

 		}

 	}

 	@Override

 	public void run(DOMResult domResult) throws OutputActionException {

 		XPathExpression xpathExpression = null;

 		try {

 			Node document = domResult.getNode();

 			xpath.setNamespaceContext(new DocumentNamespaceContext(document));

 			try {

 				xpathExpression = xpath.compile(expressionString);

 			} catch (XPathExpressionException e) {

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

 			}

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

 				if (nodeSet) {

 					NodeList result = (NodeList) xpathExpression.evaluate(document, XPathConstants.NODESET);

 					for (int i = 0; i < result.getLength(); i++) {

 						Node node = result.item(i);

 						log.log(Level.FINE, "Node type: {0}", node.getClass());

 						final String stringValue;

 						if (node instanceof Attr) {

 							Attr attribute = (Attr) node;

 							stringValue = attribute.getValue();

 						} else if (node instanceof Element) {

 							stringValue = nodeToString(node);

 							/**

 							 * TODO: print/log node separator

 							 */

 						} else {

 							stringValue = String.valueOf(node);

 						}

 						out.print(stringValue);

 						/**

 						 * TODO: support also null-byte-separated values

 						 */

 						if (lineBreak) {

 							out.println();

 						}

 					}

 				} else {

 					log.log(Level.FINE, "String value, no node-set");

 					out.print(xpathExpression.evaluate(document));

 					if (lineBreak) {

 						out.println();

 					}

 				}

 			}

 		} catch (XPathExpressionException e) {

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

 		}

 	}

 }