/**

 * 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);

		}

	}

}