import java.util.concurrent.Executor;

import org.jboss.netty.channel.ChannelDownstreamHandler;
import org.jboss.netty.channel.ChannelEvent;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelUpstreamHandler;
import org.jboss.netty.channel.ChannelHandler.Sharable;
import org.jboss.netty.handler.execution.ChannelEventRunnable;
import org.jboss.netty.util.ExternalResourceReleasable;
import org.jboss.netty.util.internal.ExecutorUtil;

@Sharable
public class DownStreamExecutionHandler implements ChannelUpstreamHandler,
		ChannelDownstreamHandler, ExternalResourceReleasable {

	private final Executor executor;

	/**
	 * Creates a new instance with the specified {@link Executor}.
	 */
	public DownStreamExecutionHandler(Executor executor) {
		if (executor == null) {
			throw new NullPointerException("executor");
		}
		this.executor = executor;
	}

	/**
	 * Returns the {@link Executor} which was specified with the constructor.
	 */
	public Executor getExecutor() {
		return executor;
	}

	/**
	 * Shuts down the {@link Executor} which was specified with the constructor
	 * and wait for its termination.
	 */
	public void releaseExternalResources() {
		ExecutorUtil.terminate(getExecutor());
	}

	public void handleUpstream(ChannelHandlerContext context, ChannelEvent e)
			throws Exception {
		context.sendUpstream(e);
	}

	public void handleDownstream(ChannelHandlerContext ctx, ChannelEvent e)
			throws Exception {
		executor.execute(new ChannelEventRunnable(ctx, e));
	}
}