/*
  GRANITE DATA SERVICES
  Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.

  This file is part of Granite Data Services.

  Granite Data Services is free software; you can redistribute it and/or modify
  it under the terms of the GNU Library General Public License as published by
  the Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  Granite Data Services is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
  for more details.

  You should have received a copy of the GNU Library General Public License
  along with this library; if not, see <http://www.gnu.org/licenses/>.
*/

package org.granite.gravity.jbossweb;

import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.granite.gravity.AbstractGravityServlet;
import org.granite.gravity.tomcat.CometIO;
import org.granite.logging.Logger;
import org.jboss.servlet.http.HttpEvent;
import org.jboss.servlet.http.HttpEventServlet;

/**
 * @author Franck WOLFF
 */
public abstract class AbstractHttpEventServlet extends AbstractGravityServlet implements HttpEventServlet {

    ///////////////////////////////////////////////////////////////////////////
    // Fields.

    private static final long serialVersionUID = 1L;
    private static final Logger log = Logger.getLogger(AbstractHttpEventServlet.class);
    
    private boolean longPollingTimeoutSupported = true;

    ///////////////////////////////////////////////////////////////////////////
    // Abstract methods.

        public abstract CometIO createCometIO();
        
    public abstract boolean handleRequest(HttpEvent event, InputStream content)
        throws IOException, ServletException;

    public abstract boolean handleEnd(HttpEvent event)
        throws IOException, ServletException;

    public abstract boolean handleError(HttpEvent event)
        throws IOException, ServletException;

    ///////////////////////////////////////////////////////////////////////////
    // CometProcessor implementation.

    public void event(HttpEvent event) throws IOException, ServletException {
        
        // make sure we've got a valid CometEvent (should never happen)
        if (!EventUtil.isValid(event)) {
                log.error("JBossWeb sent an invalid HttpEvent: %s", event.getType());
                return;
        }

        if (log.isDebugEnabled()) {
                log.debug(
                    "%s: %s/%s",
                    event.getType(),
                    event.getHttpServletRequest(), event.getHttpServletResponse()
                );
        }

        if (event.getType() == HttpEvent.EventType.BEGIN)
            begin(event);
        else if (event.getType() == HttpEvent.EventType.READ)
            read(event);
        else if (event.getType() == HttpEvent.EventType.END)
            end(event);
        else if (event.getType() == HttpEvent.EventType.ERROR 
                || event.getType() == HttpEvent.EventType.EOF 
                || event.getType() == HttpEvent.EventType.TIMEOUT)
            error(event);
        else
            throw new ServletException("Unknown HttpEvent type: " + event.getType());
    }

    ///////////////////////////////////////////////////////////////////////////
    // Comet events processing.

    protected void begin(HttpEvent event) throws IOException, ServletException {
        boolean close = true;
        try {
                // Event timeout isn't supported with APR connectors...
                if (longPollingTimeoutSupported) {
                        try {
                                event.setTimeout((int)getLongPollingTimeout());
                        }
                        catch (Exception e) {
                                longPollingTimeoutSupported = false;
                        }
                }

                HttpServletRequest request = event.getHttpServletRequest();
            CometIO io = createCometIO();
                io.readFully(request.getInputStream());
                
                close = handleRequest(event, io.getInputStream());
        }
        finally {
                if (close) {
                try {
                        event.close();
                } catch (Exception e) {
                        log.debug(e, "Could not close event: %s", EventUtil.toString(event));
                }
                }
        }
    }

        protected void read(HttpEvent event) {
                // This implementation doesn't use asynchronous reads.
                throw new RuntimeException("Unsupported operation");
    }
    
        protected void end(HttpEvent event) throws IOException, ServletException {
                boolean close = true;
                try {
                        close = handleEnd(event);
                }
                finally {
                        if (close) {
                        try {
                                event.close();
                        } catch (Exception e) {
                                log.debug(e, "Could not close event: %s", EventUtil.toString(event));
                        }
                        }
        }
    }
    
    protected void error(HttpEvent event) throws IOException, ServletException {
        boolean close = true;
        try {
                close = handleError(event);
        }
        finally {
                if (close) {
                        try {
                                event.close();
                        } catch (Exception e) {
                                log.debug(e, "Could not close event: %s", EventUtil.toString(event));
                        }
                }
        }
    }

    ///////////////////////////////////////////////////////////////////////////
    // Utility.

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response)
        throws IOException, ServletException {
        throw new ServletException("Not in a valid Comet configuration (use an APR or NIO connector)");
    }
}