/*
 * 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.springframework.security.web.authentication;

import java.io.IOException;

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

import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.context.MessageSource;
import org.springframework.context.MessageSourceAware;
import org.springframework.context.support.MessageSourceAccessor;
import org.springframework.security.authentication.AuthenticationDetailsSource;
import org.springframework.security.authentication.AuthenticationManager;
import org.springframework.security.authentication.InternalAuthenticationServiceException;
import org.springframework.security.authentication.event.InteractiveAuthenticationSuccessEvent;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.SpringSecurityMessageSource;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.authentication.session.NullAuthenticatedSessionStrategy;
import org.springframework.security.web.authentication.session.SessionAuthenticationStrategy;
import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.util.Assert;
import org.springframework.web.filter.GenericFilterBean;

/**
 * Abstract processor of browser-based HTTP-based authentication requests.
 *
 * <h3>Authentication Process</h3>
 *
 * The filter requires that you set the <tt>authenticationManager</tt> property. An
 * <tt>AuthenticationManager</tt> is required to process the authentication request tokens
 * created by implementing classes.
 * <p>
 * This filter will intercept a request and attempt to perform authentication from that
 * request if the request matches the
 * {@link #setRequiresAuthenticationRequestMatcher(RequestMatcher)}.
 * <p>
 * Authentication is performed by the
 * {@link #attemptAuthentication(HttpServletRequest, HttpServletResponse)
 * attemptAuthentication} method, which must be implemented by subclasses.
 *
 * <h4>Authentication Success</h4>
 *
 * If authentication is successful, the resulting {@link Authentication} object will be
 * placed into the <code>SecurityContext</code> for the current thread, which is
 * guaranteed to have already been created by an earlier filter.
 * <p>
 * The configured {@link #setAuthenticationSuccessHandler(AuthenticationSuccessHandler)
 * AuthenticationSuccessHandler} will then be called to take the redirect to the
 * appropriate destination after a successful login. The default behaviour is implemented
 * in a {@link SavedRequestAwareAuthenticationSuccessHandler} which will make use of any
 * <tt>DefaultSavedRequest</tt> set by the <tt>ExceptionTranslationFilter</tt> and
 * redirect the user to the URL contained therein. Otherwise it will redirect to the
 * webapp root "/". You can customize this behaviour by injecting a differently configured
 * instance of this class, or by using a different implementation.
 * <p>
 * See the
 * {@link #successfulAuthentication(HttpServletRequest, HttpServletResponse, FilterChain, Authentication)}
 * method for more information.
 *
 * <h4>Authentication Failure</h4>
 *
 * If authentication fails, it will delegate to the configured
 * {@link AuthenticationFailureHandler} to allow the failure information to be conveyed to
 * the client. The default implementation is {@link SimpleUrlAuthenticationFailureHandler}
 * , which sends a 401 error code to the client. It may also be configured with a failure
 * URL as an alternative. Again you can inject whatever behaviour you require here.
 *
 * <h4>Event Publication</h4>
 *
 * If authentication is successful, an {@link InteractiveAuthenticationSuccessEvent} will
 * be published via the application context. No events will be published if authentication
 * was unsuccessful, because this would generally be recorded via an
 * {@code AuthenticationManager}-specific application event.
 *
 * <h4>Session Authentication</h4>
 *
 * The class has an optional {@link SessionAuthenticationStrategy} which will be invoked
 * immediately after a successful call to {@code attemptAuthentication()}. Different
 * implementations
 * {@link #setSessionAuthenticationStrategy(SessionAuthenticationStrategy) can be
 * injected} to enable things like session-fixation attack prevention or to control the
 * number of simultaneous sessions a principal may have.
 *
 * @author Ben Alex
 * @author Luke Taylor
 */
public abstract class AbstractAuthenticationProcessingFilter extends GenericFilterBean
		implements ApplicationEventPublisherAware, MessageSourceAware {
	// ~ Static fields/initializers
	// =====================================================================================

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

	protected ApplicationEventPublisher eventPublisher;
	protected AuthenticationDetailsSource<HttpServletRequest, ?> authenticationDetailsSource = new WebAuthenticationDetailsSource();
	private AuthenticationManager authenticationManager;
	protected MessageSourceAccessor messages = SpringSecurityMessageSource.getAccessor();
	private RememberMeServices rememberMeServices = new NullRememberMeServices();

	private RequestMatcher requiresAuthenticationRequestMatcher;

	private boolean continueChainBeforeSuccessfulAuthentication = false;

	private SessionAuthenticationStrategy sessionStrategy = new NullAuthenticatedSessionStrategy();

	private boolean allowSessionCreation = true;

	private AuthenticationSuccessHandler successHandler = new SavedRequestAwareAuthenticationSuccessHandler();
	private AuthenticationFailureHandler failureHandler = new SimpleUrlAuthenticationFailureHandler();

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

	/**
	 * @param defaultFilterProcessesUrl the default value for <tt>filterProcessesUrl</tt>.
	 */
	protected AbstractAuthenticationProcessingFilter(String defaultFilterProcessesUrl) {
		setFilterProcessesUrl(defaultFilterProcessesUrl);
	}

	/**
	 * Creates a new instance
	 *
	 * @param requiresAuthenticationRequestMatcher the {@link RequestMatcher} used to
	 * determine if authentication is required. Cannot be null.
	 */
	protected AbstractAuthenticationProcessingFilter(
			RequestMatcher requiresAuthenticationRequestMatcher) {
		Assert.notNull(requiresAuthenticationRequestMatcher,
				"requiresAuthenticationRequestMatcher cannot be null");
		this.requiresAuthenticationRequestMatcher = requiresAuthenticationRequestMatcher;
	}

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

	@Override
	public void afterPropertiesSet() {
		Assert.notNull(authenticationManager, "authenticationManager must be specified");
	}

	/**
	 * Invokes the
	 * {@link #requiresAuthentication(HttpServletRequest, HttpServletResponse)
	 * requiresAuthentication} method to determine whether the request is for
	 * authentication and should be handled by this filter. If it is an authentication
	 * request, the
	 * {@link #attemptAuthentication(HttpServletRequest, HttpServletResponse)
	 * attemptAuthentication} will be invoked to perform the authentication. There are
	 * then three possible outcomes:
	 * <ol>
	 * <li>An <tt>Authentication</tt> object is returned. The configured
	 * {@link SessionAuthenticationStrategy} will be invoked (to handle any
	 * session-related behaviour such as creating a new session to protect against
	 * session-fixation attacks) followed by the invocation of
	 * {@link #successfulAuthentication(HttpServletRequest, HttpServletResponse, FilterChain, Authentication)}
	 * method</li>
	 * <li>An <tt>AuthenticationException</tt> occurs during authentication. The
	 * {@link #unsuccessfulAuthentication(HttpServletRequest, HttpServletResponse, AuthenticationException)
	 * unsuccessfulAuthentication} method will be invoked</li>
	 * <li>Null is returned, indicating that the authentication process is incomplete. The
	 * method will then return immediately, assuming that the subclass has done any
	 * necessary work (such as redirects) to continue the authentication process. The
	 * assumption is that a later request will be received by this method where the
	 * returned <tt>Authentication</tt> object is not null.
	 * </ol>
	 */
	public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
			throws IOException, ServletException {

		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) res;

		if (!requiresAuthentication(request, response)) {
			chain.doFilter(request, response);

			return;
		}

		if (logger.isDebugEnabled()) {
			logger.debug("Request is to process authentication");
		}

		Authentication authResult;

		try {
			authResult = attemptAuthentication(request, response);
			if (authResult == null) {
				// return immediately as subclass has indicated that it hasn't completed
				// authentication
				return;
			}
			sessionStrategy.onAuthentication(authResult, request, response);
		}
		catch (InternalAuthenticationServiceException failed) {
			logger.error(
					"An internal error occurred while trying to authenticate the user.",
					failed);
			unsuccessfulAuthentication(request, response, failed);

			return;
		}
		catch (AuthenticationException failed) {
			// Authentication failed
			unsuccessfulAuthentication(request, response, failed);

			return;
		}

		// Authentication success
		if (continueChainBeforeSuccessfulAuthentication) {
			chain.doFilter(request, response);
		}

		successfulAuthentication(request, response, chain, authResult);
	}

	/**
	 * Indicates whether this filter should attempt to process a login request for the
	 * current invocation.
	 * <p>
	 * It strips any parameters from the "path" section of the request URL (such as the
	 * jsessionid parameter in <em>http://host/myapp/index.html;jsessionid=blah</em>)
	 * before matching against the <code>filterProcessesUrl</code> property.
	 * <p>
	 * Subclasses may override for special requirements, such as Tapestry integration.
	 *
	 * @return <code>true</code> if the filter should attempt authentication,
	 * <code>false</code> otherwise.
	 */
	protected boolean requiresAuthentication(HttpServletRequest request,
			HttpServletResponse response) {
		return requiresAuthenticationRequestMatcher.matches(request);
	}

	/**
	 * Performs actual authentication.
	 * <p>
	 * The implementation should do one of the following:
	 * <ol>
	 * <li>Return a populated authentication token for the authenticated user, indicating
	 * successful authentication</li>
	 * <li>Return null, indicating that the authentication process is still in progress.
	 * Before returning, the implementation should perform any additional work required to
	 * complete the process.</li>
	 * <li>Throw an <tt>AuthenticationException</tt> if the authentication process fails</li>
	 * </ol>
	 *
	 * @param request from which to extract parameters and perform the authentication
	 * @param response the response, which may be needed if the implementation has to do a
	 * redirect as part of a multi-stage authentication process (such as OpenID).
	 *
	 * @return the authenticated user token, or null if authentication is incomplete.
	 *
	 * @throws AuthenticationException if authentication fails.
	 */
	public abstract Authentication attemptAuthentication(HttpServletRequest request,
			HttpServletResponse response) throws AuthenticationException, IOException,
			ServletException;

	/**
	 * Default behaviour for successful authentication.
	 * <ol>
	 * <li>Sets the successful <tt>Authentication</tt> object on the
	 * {@link SecurityContextHolder}</li>
	 * <li>Informs the configured <tt>RememberMeServices</tt> of the successful login</li>
	 * <li>Fires an {@link InteractiveAuthenticationSuccessEvent} via the configured
	 * <tt>ApplicationEventPublisher</tt></li>
	 * <li>Delegates additional behaviour to the {@link AuthenticationSuccessHandler}.</li>
	 * </ol>
	 *
	 * Subclasses can override this method to continue the {@link FilterChain} after
	 * successful authentication.
	 * @param request
	 * @param response
	 * @param chain
	 * @param authResult the object returned from the <tt>attemptAuthentication</tt>
	 * method.
	 * @throws IOException
	 * @throws ServletException
	 */
	protected void successfulAuthentication(HttpServletRequest request,
			HttpServletResponse response, FilterChain chain, Authentication authResult)
			throws IOException, ServletException {

		if (logger.isDebugEnabled()) {
			logger.debug("Authentication success. Updating SecurityContextHolder to contain: "
					+ authResult);
		}

		SecurityContextHolder.getContext().setAuthentication(authResult);

		rememberMeServices.loginSuccess(request, response, authResult);

		// Fire event
		if (this.eventPublisher != null) {
			eventPublisher.publishEvent(new InteractiveAuthenticationSuccessEvent(
					authResult, this.getClass()));
		}

		successHandler.onAuthenticationSuccess(request, response, authResult);
	}

	/**
	 * Default behaviour for unsuccessful authentication.
	 * <ol>
	 * <li>Clears the {@link SecurityContextHolder}</li>
	 * <li>Stores the exception in the session (if it exists or
	 * <tt>allowSesssionCreation</tt> is set to <tt>true</tt>)</li>
	 * <li>Informs the configured <tt>RememberMeServices</tt> of the failed login</li>
	 * <li>Delegates additional behaviour to the {@link AuthenticationFailureHandler}.</li>
	 * </ol>
	 */
	protected void unsuccessfulAuthentication(HttpServletRequest request,
			HttpServletResponse response, AuthenticationException failed)
			throws IOException, ServletException {
		SecurityContextHolder.clearContext();

		if (logger.isDebugEnabled()) {
			logger.debug("Authentication request failed: " + failed.toString(), failed);
			logger.debug("Updated SecurityContextHolder to contain null Authentication");
			logger.debug("Delegating to authentication failure handler " + failureHandler);
		}

		rememberMeServices.loginFail(request, response);

		failureHandler.onAuthenticationFailure(request, response, failed);
	}

	protected AuthenticationManager getAuthenticationManager() {
		return authenticationManager;
	}

	public void setAuthenticationManager(AuthenticationManager authenticationManager) {
		this.authenticationManager = authenticationManager;
	}

	/**
	 * Sets the URL that determines if authentication is required
	 *
	 * @param filterProcessesUrl
	 */
	public void setFilterProcessesUrl(String filterProcessesUrl) {
		setRequiresAuthenticationRequestMatcher(new AntPathRequestMatcher(
				filterProcessesUrl));
	}

	public final void setRequiresAuthenticationRequestMatcher(
			RequestMatcher requestMatcher) {
		Assert.notNull(requestMatcher, "requestMatcher cannot be null");
		this.requiresAuthenticationRequestMatcher = requestMatcher;
	}

	public RememberMeServices getRememberMeServices() {
		return rememberMeServices;
	}

	public void setRememberMeServices(RememberMeServices rememberMeServices) {
		Assert.notNull(rememberMeServices, "rememberMeServices cannot be null");
		this.rememberMeServices = rememberMeServices;
	}

	/**
	 * Indicates if the filter chain should be continued prior to delegation to
	 * {@link #successfulAuthentication(HttpServletRequest, HttpServletResponse, FilterChain, Authentication)}
	 * , which may be useful in certain environment (such as Tapestry applications).
	 * Defaults to <code>false</code>.
	 */
	public void setContinueChainBeforeSuccessfulAuthentication(
			boolean continueChainBeforeSuccessfulAuthentication) {
		this.continueChainBeforeSuccessfulAuthentication = continueChainBeforeSuccessfulAuthentication;
	}

	public void setApplicationEventPublisher(ApplicationEventPublisher eventPublisher) {
		this.eventPublisher = eventPublisher;
	}

	public void setAuthenticationDetailsSource(
			AuthenticationDetailsSource<HttpServletRequest, ?> authenticationDetailsSource) {
		Assert.notNull(authenticationDetailsSource,
				"AuthenticationDetailsSource required");
		this.authenticationDetailsSource = authenticationDetailsSource;
	}

	public void setMessageSource(MessageSource messageSource) {
		this.messages = new MessageSourceAccessor(messageSource);
	}

	protected boolean getAllowSessionCreation() {
		return allowSessionCreation;
	}

	public void setAllowSessionCreation(boolean allowSessionCreation) {
		this.allowSessionCreation = allowSessionCreation;
	}

	/**
	 * The session handling strategy which will be invoked immediately after an
	 * authentication request is successfully processed by the
	 * <tt>AuthenticationManager</tt>. Used, for example, to handle changing of the
	 * session identifier to prevent session fixation attacks.
	 *
	 * @param sessionStrategy the implementation to use. If not set a null implementation
	 * is used.
	 */
	public void setSessionAuthenticationStrategy(
			SessionAuthenticationStrategy sessionStrategy) {
		this.sessionStrategy = sessionStrategy;
	}

	/**
	 * Sets the strategy used to handle a successful authentication. By default a
	 * {@link SavedRequestAwareAuthenticationSuccessHandler} is used.
	 */
	public void setAuthenticationSuccessHandler(
			AuthenticationSuccessHandler successHandler) {
		Assert.notNull(successHandler, "successHandler cannot be null");
		this.successHandler = successHandler;
	}

	public void setAuthenticationFailureHandler(
			AuthenticationFailureHandler failureHandler) {
		Assert.notNull(failureHandler, "failureHandler cannot be null");
		this.failureHandler = failureHandler;
	}

	protected AuthenticationSuccessHandler getSuccessHandler() {
		return successHandler;
	}

	protected AuthenticationFailureHandler getFailureHandler() {
		return failureHandler;
	}
}
