/**
 * Copyright 2007-2016, Kaazing Corporation. 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.
 */
package org.apache.mina.handler.chain;

import org.apache.mina.core.service.IoHandler;
import org.apache.mina.core.service.IoHandlerAdapter;
import org.apache.mina.core.session.IoSession;

/**
 * An {@link IoHandler} which executes an {@link IoHandlerChain}
 * on a <tt>messageReceived</tt> event.
 *
 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
 */
public class ChainedIoHandler extends IoHandlerAdapter {
    private final IoHandlerChain chain;

    /**
     * Creates a new instance which contains an empty {@link IoHandlerChain}.
     */
    public ChainedIoHandler() {
        chain = new IoHandlerChain();
    }

    /**
     * Creates a new instance which executes the specified
     * {@link IoHandlerChain} on a <tt>messageReceived</tt> event.
     *
     * @param chain an {@link IoHandlerChain} to execute
     */
    public ChainedIoHandler(IoHandlerChain chain) {
        if (chain == null) {
            throw new NullPointerException("chain");
        }
        this.chain = chain;
    }

    /**
     * Returns the {@link IoHandlerCommand} this handler will use to
     * handle <tt>messageReceived</tt> events.
     */
    public IoHandlerChain getChain() {
        return chain;
    }

    /**
     * Handles the specified <tt>messageReceived</tt> event with the
     * {@link IoHandlerCommand} or {@link IoHandlerChain} you specified
     * in the constructor.
     */
    @Override
    public void messageReceived(IoSession session, Object message)
            throws Exception {
        chain.execute(null, session, message);
    }
}
