/**
 * 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.cxf.ws.rm;

import java.util.Collection;
import java.util.List;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.namespace.QName;

import org.w3c.dom.Element;

import org.apache.cxf.databinding.DataBinding;
import org.apache.cxf.headers.Header;
import org.apache.cxf.jaxb.JAXBDataBinding;
import org.apache.cxf.ws.rm.v200702.AckRequestedType;
import org.apache.cxf.ws.rm.v200702.CloseSequenceType;
import org.apache.cxf.ws.rm.v200702.CreateSequenceResponseType;
import org.apache.cxf.ws.rm.v200702.CreateSequenceType;
import org.apache.cxf.ws.rm.v200702.Identifier;
import org.apache.cxf.ws.rm.v200702.SequenceAcknowledgement;
import org.apache.cxf.ws.rm.v200702.SequenceType;
import org.apache.cxf.ws.rm.v200702.TerminateSequenceType;

/**
 * Base class for converting WS-ReliableMessaging structures to and from XML. Subclasses provide version-specific
 * encoding and decoding.
 */
public abstract class EncoderDecoder {
    protected volatile DataBinding databinding;
    
    /**
     * Get context for JAXB marshalling/unmarshalling.
     *
     * @return context
     * @throws JAXBException
     */
    protected abstract JAXBContext getContext() throws JAXBException;
        

    /**
     * Get the WS-ReliableMessaging namespace used by this encoder/decoder.
     *
     * @return URI
     */
    public abstract String getWSRMNamespace();

    /**
     * Get the WS-Addressing namespace used by this encoder/decoder.
     *
     * @return URI
     */
    public abstract String getWSANamespace();

    /**
     * Get the WS-ReliableMessaging constants used by this encoder/decoder.
     *
     * @return
     */
    public abstract RMConstants getConstants();

    /**
     * Get the class used for the CreateSequenceType.
     *
     * @return class
     */
    public abstract Class<?> getCreateSequenceType();

    /**
     * Get the class used for the CreateSequenceResponseType.
     *
     * @return class
     */
    public abstract Class<?> getCreateSequenceResponseType();

    /**
     * Get the class used for the TerminateSequenceType.
     *
     * @return class
     */
    public abstract Class<?> getTerminateSequenceType();

    /**
     * Get the class used for the TerminateSequenceResponseType.
     *
     * @return class
     */
    public abstract Class<?> getTerminateSequenceResponseType();

    
    /**
     * Get the databinding used for the header objects
     * @return databinding
     */
    protected DataBinding getDataBinding() throws JAXBException {
        DataBinding result = databinding;
        if (result == null) {
            synchronized (this) {
                result = databinding;
                if (result == null) {
                    result = new JAXBDataBinding(getContext());
                    databinding = result;
                }
            }
        }
        return result;
    }

    
    /**
     * Builds an element containing WS-RM headers. This adds the appropriate WS-RM namespace declaration to the element,
     * and then adds any WS-RM headers set in the supplied properties as child elements.
     *
     * @param rmps
     * @param qname constructed element name
     * @return element (<code>null</code> if none)
     */
    public void buildHeaders(RMProperties rmps, List<Header> headers) throws JAXBException {

        // check if there's anything to insert
        SequenceType seq = rmps.getSequence();
        Collection<SequenceAcknowledgement> acks = rmps.getAcks();
        Collection<AckRequestedType> reqs = rmps.getAcksRequested();
        if (seq == null && acks == null && reqs == null) {
            return;
        }

        buildHeaders(seq, acks, reqs, rmps.isLastMessage(), headers);
    }

    /**
     * Builds an element containing a WS-RM Fault. This adds the appropriate WS-RM namespace declaration to
     * the element, and then adds the Fault as a child element.
     *
     * @param sf
     * @param qname constructed element name
     * @return element
     */
    public Header buildHeaderFault(SequenceFault sf) throws JAXBException {
        Object o = buildHeaderFaultObject(sf);
        
        return new Header(new QName(getConstants().getWSRMNamespace(),
                                    RMConstants.SEQUENCE_FAULT_NAME),
                          o, getDataBinding());
    }

    /**
     * Build all required headers, using the correct protocol variation.
     *
     * @param seq
     * @param acks
     * @param reqs
     * @param last
     * @param header
     * @param marshaller
     * @throws JAXBException
     */
    protected abstract void buildHeaders(SequenceType seq, Collection<SequenceAcknowledgement> acks,
        Collection<AckRequestedType> reqs, boolean last, List<Header> headers) throws JAXBException;

    /**
     * Build a header fault, using the correct protocol variation.
     *
     * @param sf
     * @return the object marshallable with the JAXContext 
     */
    protected abstract Object buildHeaderFaultObject(SequenceFault sf);

    /**
     * Marshals a SequenceAcknowledgement to the appropriate external form.
     *
     * @param ack
     * @return element
     * @throws JAXBException
     */
    public abstract Element encodeSequenceAcknowledgement(SequenceAcknowledgement ack) throws JAXBException;

    /**
     * Marshals an Identifier to the appropriate external form.
     *
     * @param id
     * @return element
     * @throws JAXBException
     */
    public abstract Element encodeIdentifier(Identifier id) throws JAXBException;

    /**
     * Unmarshals a SequenceType, converting it if necessary to the internal form.
     *
     * @param elem
     * @return
     * @throws JAXBException
     */
    public abstract SequenceType decodeSequenceType(Element elem) throws JAXBException;

    /**
     * Generates a CloseSequenceType if a SequenceType represents a last message state.
     *
     * @param elem
     * @return CloseSequenceType if last message state, else <code>null</code>
     * @throws JAXBException
     */
    public abstract CloseSequenceType decodeSequenceTypeCloseSequence(Element elem) throws JAXBException;

    /**
     * Unmarshals a SequenceAcknowledgement, converting it if necessary to the internal form.
     *
     * @param elem
     * @return
     * @throws JAXBException
     */
    public abstract SequenceAcknowledgement decodeSequenceAcknowledgement(Element elem) throws JAXBException;

    /**
     * Unmarshals a AckRequestedType, converting it if necessary to the internal form.
     *
     * @param elem
     * @return
     * @throws JAXBException
     */
    public abstract AckRequestedType decodeAckRequestedType(Element elem) throws JAXBException;

    /**
     * Convert a CreateSequence message to the correct format for transmission.
     *
     * @param create
     * @return converted
     */
    public abstract Object convertToSend(CreateSequenceType create);

    /**
     * Convert a CreateSequenceResponse message to the correct format for transmission.
     *
     * @param create
     * @return converted
     */
    public abstract Object convertToSend(CreateSequenceResponseType create);

    /**
     * Convert a TerminateSequence message to the correct format for transmission.
     *
     * @param term
     * @return converted
     */
    public abstract Object convertToSend(TerminateSequenceType term);

    /**
     * Convert a received TerminateSequence message to internal form.
     *
     * @param term
     * @return converted
     */
    public abstract TerminateSequenceType convertReceivedTerminateSequence(Object term);

    /**
     * Convert a received CreateSequence message to internal form.
     *
     * @param create
     * @return converted
     */
    public abstract CreateSequenceType convertReceivedCreateSequence(Object create);

    /**
     * Convert a received CreateSequenceResponse message to internal form.
     *
     * @param create
     * @return converted
     */
    public abstract CreateSequenceResponseType convertReceivedCreateSequenceResponse(Object create);
}