/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.
 */

package org.apache.synapse.config.xml;

import org.apache.synapse.mediators.eip.Target;
import org.apache.synapse.SynapseException;
import org.apache.synapse.config.xml.endpoints.EndpointFactory;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.OMAttribute;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import javax.xml.namespace.QName;

/**
 * Factory for {@link Target} instances.
 * <p>
 * This will build the Target util object for EIP mediators using
 * &lt;target&gt; element specified as follows
 *
 * &lt;target (sequence="string reference")? (endpoint="string reference")?&gt;
 *  (&lt;sequence&gt; | &lt;endpoinit&gt;)?
 * &lt;/target&gt;
 */
public class TargetFactory {

    /**
     * This will hold the logger for the logging purposes
     */
    private static final Log log = LogFactory.getLog(TargetFactory.class);

    /**
     * Holds the QName of the target element in the xml configuration
     */
    private static final QName TARGET_Q = new QName(XMLConfigConstants.SYNAPSE_NAMESPACE, "target");

    /**
     * This static method will be used to build the Target from the specified element
     * 
     * @param elem - OMElement describing the xml configuration of the target
     * @return Target built by parsing the given element
     */
    public static Target createTarget(OMElement elem) {

        if (!TARGET_Q.equals(elem.getQName())) {
            handleException("Element does not match with the target QName");
        }

        Target target = new Target();
        OMAttribute toAttr = elem.getAttribute(new QName(XMLConfigConstants.NULL_NAMESPACE, "to"));
        if (toAttr != null && toAttr.getAttributeValue() != null) {
            target.setToAddress(toAttr.getAttributeValue());
        }

        OMAttribute soapAction = elem.getAttribute(
                new QName(XMLConfigConstants.NULL_NAMESPACE, "soapAction"));
        if (soapAction != null && soapAction.getAttributeValue() != null) {
            target.setSoapAction(soapAction.getAttributeValue());
        }

        OMAttribute sequenceAttr = elem.getAttribute(
                new QName(XMLConfigConstants.NULL_NAMESPACE, "sequence"));
        if (sequenceAttr != null && sequenceAttr.getAttributeValue() != null) {
            target.setSequenceRef(sequenceAttr.getAttributeValue());
        }

        OMAttribute endpointAttr = elem.getAttribute(
                new QName(XMLConfigConstants.NULL_NAMESPACE, "endpoint"));
        if (endpointAttr != null && endpointAttr.getAttributeValue() != null) {
            target.setEndpointRef(endpointAttr.getAttributeValue());
        }

        OMElement sequence = elem.getFirstChildWithName(
                new QName(XMLConfigConstants.SYNAPSE_NAMESPACE, "sequence"));
        if (sequence != null) {
            SequenceMediatorFactory fac = new SequenceMediatorFactory();
            target.setSequence(fac.createAnonymousSequence(sequence));
        }

        OMElement endpoint = elem.getFirstChildWithName(
                new QName(XMLConfigConstants.SYNAPSE_NAMESPACE, "endpoint"));
        if (endpoint != null) {
            target.setEndpoint(EndpointFactory.getEndpointFromElement(endpoint, true));
        }

        return target;
    }

    /**
     * This private method is used for exception handling and logging purposes.
     *
     * @param message - String message to be logged and the message of the exception
     */
    private static void handleException (String message) {
        if (log.isDebugEnabled()) {
            log.debug(message);
        }
        throw new SynapseException(message);
    }
}
