/*
 * JBoss, Home of Professional Open Source
 * Copyright 2013, Red Hat, Inc. and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.richfaces.webapp;

import java.io.IOException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.richfaces.log.Logger;
import org.richfaces.log.RichfacesLogger;

import com.google.common.collect.Iterators;
import com.google.common.collect.Sets;

/**
 *
 * @author Nick Belaevski
 */
public class PushFilter implements Filter {
    private static final long serialVersionUID = 7616370505508715222L;
    private static final Logger LOGGER = RichfacesLogger.WEBAPP.getLogger();

    private PushServlet pushServlet;
    private ServletConfigFacade servletConfig;

    public void init(FilterConfig filterConfig) throws ServletException {
        logPushFilterWarning(filterConfig.getServletContext());
        servletConfig = new ServletConfigFacade(filterConfig);
    }

    private void logPushFilterWarning(ServletContext servletContext) {
        String message;

        if (servletContext.getMajorVersion() >= 3) {
            message = "PushFilter has been deprecated, you can remove its declaration in Servlets 3 environment";
        } else {
            message = "PushFilter has been deprecated, you should use PushServlet instead";
        }

        LOGGER.warn(message);
    }

    /*
     * (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
        ServletException {
        if (request instanceof HttpServletRequest && response instanceof HttpServletResponse) {
            HttpServletRequest httpReq = (HttpServletRequest) request;
            HttpServletResponse httpResp = (HttpServletResponse) response;

            if ("GET".equals(httpReq.getMethod()) && httpReq.getQueryString() != null
                && httpReq.getQueryString().contains("__richfacesPushAsync")) {
                if (pushServlet == null) {
                    pushServlet = new PushServlet();
                    pushServlet.init(servletConfig);
                }
                pushServlet.doGet(httpReq, httpResp);
                return;
            }
        }

        chain.doFilter(request, response);
    }

    /*
     * (non-Javadoc)
     * @see javax.servlet.Filter#destroy()
     */
    @Override
    public void destroy() {
        if (pushServlet != null) {
            pushServlet.destroy();
            pushServlet = null;
        }
    }

    private final class ServletConfigFacade implements ServletConfig {
        private final FilterConfig filterConfig;

        private ServletConfigFacade(FilterConfig filterConfig) {
            this.filterConfig = filterConfig;
        }

        public String getServletName() {
            return filterConfig.getFilterName();
        }

        public ServletContext getServletContext() {
            return filterConfig.getServletContext();
        }

        public String getInitParameter(String name) {
            String result = filterConfig.getInitParameter(name);

            if (result == null) {
                result = filterConfig.getServletContext().getInitParameter(name);
            }

            return result;
        }

        public Enumeration<String> getInitParameterNames() {
            Set<String> result = Sets.newLinkedHashSet();

            result.addAll(Collections.list(filterConfig.getInitParameterNames()));
            result.addAll(Collections.list(filterConfig.getServletContext().getInitParameterNames()));

            return Iterators.asEnumeration(result.iterator());
        }
    }
}