/*
 * Copyright (c) 2011, 2017 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.grizzly.servlet;

import org.glassfish.grizzly.Grizzly;
import org.glassfish.grizzly.localization.LogMessages;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.ServletResponse;
import java.io.IOException;
import java.util.EventListener;
import java.util.logging.Level;
import java.util.logging.Logger;

Implementation of javax.servlet.FilterChain used to manage
the execution of a set of filters for a particular request.  When the
set of defined filters has all been executed, the next call to
doFilter() will execute the servlet's service()
method itself.
Author:
Craig R. McClanahan/**
 * Implementation of <code>javax.servlet.FilterChain</code> used to manage
 * the execution of a set of filters for a particular request.  When the
 * set of defined filters has all been executed, the next call to
 * <code>doFilter()</code> will execute the servlet's <code>service()</code>
 * method itself.
 *
 * @author Craig R. McClanahan
 */
final class FilterChainImpl implements FilterChain, FilterChainInvoker {

    private static final Logger LOGGER = Grizzly.logger(FilterChainImpl.class);

    
The servlet instance to be executed by this chain.
/**
     * The servlet instance to be executed by this chain.
     */
    private final Servlet servlet;
    private final WebappContext ctx;

    private final Object lock = new Object();
    private int n;

    private FilterRegistration[] filters = new FilterRegistration[0];

    
The int which is used to maintain the current position
in the filter chain.
/**
     * The int which is used to maintain the current position
     * in the filter chain.
     */
    private int pos;

    public FilterChainImpl(final Servlet servlet,
                           final WebappContext ctx) {

        this.servlet = servlet;
        this.ctx = ctx;
    }

    // ---------------------------------------------------- FilterChain Methods


    public void invokeFilterChain(ServletRequest request, ServletResponse response)
            throws IOException, ServletException {

        ServletRequestEvent event =
                new ServletRequestEvent(ctx, request);
        try {
            requestInitialized(event);
            pos = 0;
            doFilter(request, response);
        } finally {
            requestDestroyed(event);
        }

    }



    
Invoke the next filter in this chain, passing the specified request
and response.  If there are no more filters in this chain, invoke
the service() method of the servlet itself.
Params:
request – The servlet request we are processing
response – The servlet response we are creating
Throws:
IOException – if an input/output error occurs
ServletException – if a servlet exception occurs/**
     * Invoke the next filter in this chain, passing the specified request
     * and response.  If there are no more filters in this chain, invoke
     * the <code>service()</code> method of the servlet itself.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     *
     * @exception java.io.IOException if an input/output error occurs
     * @exception javax.servlet.ServletException if a servlet exception occurs
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response)
            throws IOException, ServletException {

        // Call the next filter if there is one
        if (pos < n) {

            FilterRegistration registration = filters[pos++];

            try {
                Filter filter = registration.filter;
                filter.doFilter(request, response, this);
            } catch (Exception e) {
                throw new ServletException(e);
            }

            return;
        }

        try {
            if (servlet != null) {
                servlet.service(request, response);
            }

        } catch (Exception e) {
            throw new ServletException(e);
        }

    }

    // ------------------------------------------------------- Protected Methods


    protected void addFilter(final FilterRegistration filterRegistration) {
        synchronized (lock) {
            if (n == filters.length) {
                FilterRegistration[] newFilters =
                        new FilterRegistration[n + 4];
                System.arraycopy(filters, 0, newFilters, 0, n);
                filters = newFilters;
            }

            filters[n++] = filterRegistration;
        }
    }


    // --------------------------------------------------------- Private Methods

    private void requestDestroyed(ServletRequestEvent event) {
        // TODO don't create the event unless necessary
        final EventListener[] listeners = ctx.getEventListeners();
        for (int i = 0, len = listeners.length; i < len; i++) {
            if (listeners[i] instanceof ServletRequestListener) {
                try {
                    ((ServletRequestListener) listeners[i]).requestDestroyed(event);
                } catch (Throwable t) {
                    if (LOGGER.isLoggable(Level.WARNING)) {
                        LOGGER.log(Level.WARNING,
                                LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_CONTAINER_OBJECT_DESTROYED_ERROR("requestDestroyed", "ServletRequestListener", listeners[i].getClass().getName()),
                                t);
                    }
                }
            }
        }

    }

    private void requestInitialized(ServletRequestEvent event) {
        final EventListener[] listeners = ctx.getEventListeners();
        for (int i = 0, len = listeners.length; i < len; i++) {
            if (listeners[i] instanceof ServletRequestListener) {
                try {
                    ((ServletRequestListener) listeners[i]).requestInitialized(event);
                } catch (Throwable t) {
                    if (LOGGER.isLoggable(Level.WARNING)) {
                        LOGGER.log(Level.WARNING,
                                LogMessages.WARNING_GRIZZLY_HTTP_SERVLET_CONTAINER_OBJECT_INITIALIZED_ERROR("requestDestroyed", "ServletRequestListener", listeners[i].getClass().getName()),
                                t);
                    }
                }
            }
        }
    }



}