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package org.atmosphere.handler;

import java.io.IOException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.atmosphere.cpr.AtmosphereHandler;
import org.atmosphere.cpr.AtmosphereResourceEvent;
import org.atmosphere.cpr.Broadcaster;

/**
 * Simple {@link AtmosphereHandler} that relect every call to
 * {@link Broadcaster#broadcast}. All broadcast will be by default returned
 * as it is to the suspended {@link HttpServletResponse#getOutputStream}
 * or {@link HttpServletResponse#getWriter()}
 * 
 * @author Jean-francois Arcand
 */
public abstract class AbstractReflectorAtmosphereHandler
        implements AtmosphereHandler{


    /**
     * Write the {@link AtmosphereResourceEvent#getMessage()} back to the client using
     * the {@link HttpServletResponse#getOutputStream()} or {@link HttpServletResponse#getWriter()}.
     * If a {@link org.atmosphere.cpr.Serializer} is defined, it will be invoked and the writ operation
     * will be delagated to to it.
     *
     * By default, this method will try to use {@link HttpServletResponse#getWriter()}. 
     *
     * @param event  the {@link AtmosphereResourceEvent#getMessage()}
     * @throws java.io.IOException
     */
    public void onStateChange(AtmosphereResourceEvent event)
            throws IOException {

        if (event.getMessage() == null) return;
 
        if (event.getResource().getSerializer() != null){
            event.getResource().getSerializer().write(event.getResource().getResponse().getOutputStream(),
                    event.getMessage());
        } else {
            boolean isUsingStream = false;
            try{
                event.getResource().getResponse().getWriter();
            } catch(IllegalStateException e){
                isUsingStream = true;
            }

            if (isUsingStream){
                event.getResource().getResponse().getOutputStream().write(event.getMessage().toString().getBytes());
                event.getResource().getResponse().getOutputStream().flush();
            } else {
                event.getResource().getResponse().getWriter().write(event.getMessage().toString());
                event.getResource().getResponse().getWriter().flush();
            }
        }
    }

}