/**
 * Copyright (c) 2010 Yahoo! Inc. All rights reserved.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License. See accompanying LICENSE file.
 */
package org.apache.oozie.action.decision;

import org.apache.oozie.client.WorkflowAction;
import org.apache.oozie.action.ActionExecutor;
import org.apache.oozie.action.ActionExecutorException;
import org.apache.oozie.util.XLog;
import org.apache.oozie.util.XmlUtils;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.Namespace;

import java.util.List;

public class DecisionActionExecutor extends ActionExecutor {
    public static final String ACTION_TYPE = "switch";

    private static final String TRUE = "true";

    public static final String XML_ERROR = "XML_ERROR";

    public DecisionActionExecutor() {
        super(ACTION_TYPE);
    }

    @SuppressWarnings("unchecked")
    public void start(Context context, WorkflowAction action) throws ActionExecutorException {
        XLog log = XLog.getLog(getClass());
        log.trace("start() begins");
        try {
            String confStr = action.getConf();
            context.setStartData("-", "-", "-");
            Element conf = XmlUtils.parseXml(confStr);
            Namespace ns = conf.getNamespace();

            String externalState = null;

            for (Element eval : (List<Element>) conf.getChildren("case", ns)) {
                if (TRUE.equals(eval.getTextTrim())) {
                    externalState = eval.getAttributeValue("to");
                    break;
                }
            }
            if (externalState == null) {
                Element def = conf.getChild("default", ns);
                if (def != null) {
                    externalState = def.getAttributeValue("to");
                }
            }

            if (externalState == null) {
                throw new IllegalStateException("Transition cannot be NULL");
            }
            // for decision we are piggybacking on external status to transfer the transition,
            // the {@link ActionEndCommand} does the special handling of setting it as signal value.
            context.setExecutionData(externalState, null);
        }
        catch (JDOMException ex) {
            throw new ActionExecutorException(ActionExecutorException.ErrorType.FAILED, XML_ERROR, ex.getMessage(), ex);
        }
        finally {
            log.trace("start() ends");
        }
    }

    public void end(Context context, WorkflowAction action) throws ActionExecutorException {
        context.setEndData(WorkflowAction.Status.OK, action.getExternalStatus());
    }

    public void check(Context context, WorkflowAction action) throws ActionExecutorException {
        throw new UnsupportedOperationException();
    }

    public void kill(Context context, WorkflowAction action) throws ActionExecutorException {
        throw new UnsupportedOperationException();
    }

    public boolean isCompleted(String externalStatus) {
        return true;
    }

}