/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.acegisecurity.ui.logout;

import org.acegisecurity.Authentication;

import org.acegisecurity.context.SecurityContextHolder;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.util.Assert;

import java.io.IOException;

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


/**
 * Logs a principal out.<p>Polls a series of {@link LogoutHandler}s. The handlers should be specified in the order
 * they are required. Generally you will want to call logout handlers <code>TokenBasedRememberMeServices</code> and
 * <code>SecurityContextLogoutHandler</code> (in that order).</p>
 *  <p>After logout, the URL specified by {@link #logoutSuccessUrl} will be shown.</p>
 *  <p><b>Do not use this class directly.</b> Instead configure <code>web.xml</code> to use the {@link
 * org.acegisecurity.util.FilterToBeanProxy}.</p>
 *
 * @author Ben Alex
 * @version $Id$
 */
public class LogoutFilter implements Filter {
    //~ Static fields/initializers =====================================================================================

    private static final Log logger = LogFactory.getLog(LogoutFilter.class);

    //~ Instance fields ================================================================================================

    private String filterProcessesUrl = "/j_acegi_logout";
    private String logoutSuccessUrl;
    private LogoutHandler[] handlers;

    //~ Constructors ===================================================================================================

    public LogoutFilter(String logoutSuccessUrl, LogoutHandler[] handlers) {
        Assert.hasText(logoutSuccessUrl, "LogoutSuccessUrl required");
        Assert.notEmpty(handlers, "LogoutHandlers are required");
        this.logoutSuccessUrl = logoutSuccessUrl;
        this.handlers = handlers;
    }

    //~ Methods ========================================================================================================

    /**
     * Not used. Use IoC container lifecycle methods instead.
     */
    public void destroy() {}

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
        throws IOException, ServletException {
        if (!(request instanceof HttpServletRequest)) {
            throw new ServletException("Can only process HttpServletRequest");
        }

        if (!(response instanceof HttpServletResponse)) {
            throw new ServletException("Can only process HttpServletResponse");
        }

        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        if (requiresLogout(httpRequest, httpResponse)) {
            Authentication auth = SecurityContextHolder.getContext().getAuthentication();

            if (logger.isDebugEnabled()) {
                logger.debug("Logging out user '" + auth + "' and redirecting to logout page");
            }

            if (auth != null) {
                for (int i = 0; i < handlers.length; i++) {
                    handlers[i].logout(httpRequest, httpResponse, auth);
                }
            }

            sendRedirect(httpRequest, httpResponse, logoutSuccessUrl);

            return;
        }

        chain.doFilter(request, response);
    }

    /**
     * Not used. Use IoC container lifecycle methods instead.
     *
     * @param arg0 ignored
     *
     * @throws ServletException ignored
     */
    public void init(FilterConfig arg0) throws ServletException {}

    /**
     * Allow subclasses to modify when a logout should tak eplace.
     *
     * @param request the request
     * @param response the response
     *
     * @return <code>true</code> if logout should occur, <code>false</code> otherwise
     */
    protected boolean requiresLogout(HttpServletRequest request, HttpServletResponse response) {
        String uri = request.getRequestURI();
        int pathParamIndex = uri.indexOf(';');

        if (pathParamIndex > 0) {
            // strip everything after the first semi-colon
            uri = uri.substring(0, pathParamIndex);
        }

        return uri.endsWith(request.getContextPath() + filterProcessesUrl);
    }

    /**
     * Allow subclasses to modify the redirection message.
     *
     * @param request the request
     * @param response the response
     * @param url the URL to redirect to
     *
     * @throws IOException in the event of any failure
     */
    protected void sendRedirect(HttpServletRequest request, HttpServletResponse response, String url)
        throws IOException {
        if (!url.startsWith("http://") && !url.startsWith("https://")) {
            url = request.getContextPath() + url;
        }

        response.sendRedirect(response.encodeRedirectURL(url));
    }

    public void setFilterProcessesUrl(String filterProcessesUrl) {
        Assert.hasText(filterProcessesUrl, "FilterProcessesUrl required");
        this.filterProcessesUrl = filterProcessesUrl;
    }
}
