/*
 * Copyright 2005-2014 the original author or authors.
 *
 * 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.ws.soap.security.xwss.callback;

import java.io.IOException;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.UnsupportedCallbackException;

import com.sun.xml.wss.impl.callback.PasswordValidationCallback;
import com.sun.xml.wss.impl.callback.TimestampValidationCallback;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.dao.DataAccessException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.core.userdetails.UserCache;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.security.core.userdetails.cache.NullUserCache;
import org.springframework.util.Assert;
import org.springframework.ws.soap.security.callback.AbstractCallbackHandler;
import org.springframework.ws.soap.security.callback.CleanupCallback;
import org.springframework.ws.soap.security.support.SpringSecurityUtils;

/**
 * Callback handler that validates a password digest using an Spring Security {@code UserDetailsService}. Logic
 * based on Spring Security's {@code DigestProcessingFilter}.
 *
 * <p>An Spring Security {@code UserDetailService} is used to load {@code UserDetails} from. The digest of the
 * password contained in this details object is then compared with the digest in the message.
 *
 * <p>This class only handles {@code PasswordValidationCallback}s that contain a {@code DigestPasswordRequest},
 * and throws an {@code UnsupportedCallbackException} for others.
 *
 * @author Arjen Poutsma
 * @see org.springframework.security.core.userdetails.UserDetailsService
 * @see com.sun.xml.wss.impl.callback.PasswordValidationCallback
 * @see com.sun.xml.wss.impl.callback.PasswordValidationCallback.DigestPasswordRequest
 * @since 1.5.0
 */
public class SpringDigestPasswordValidationCallbackHandler extends AbstractCallbackHandler implements InitializingBean {

	private UserCache userCache = new NullUserCache();

	private UserDetailsService userDetailsService;

	/** Sets the users cache. Not required, but can benefit performance. */
	public void setUserCache(UserCache userCache) {
		this.userCache = userCache;
	}

	/** Sets the Spring Security user details service. Required. */
	public void setUserDetailsService(UserDetailsService userDetailsService) {
		this.userDetailsService = userDetailsService;
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		Assert.notNull(userDetailsService, "userDetailsService is required");
	}

	/**
	 * Handles {@code PasswordValidationCallback}s that contain a {@code DigestPasswordRequest}, and throws an
	 * {@code UnsupportedCallbackException} for others
	 *
	 * @throws javax.security.auth.callback.UnsupportedCallbackException
	 *			when the callback is not supported
	 */
	@Override
	protected void handleInternal(Callback callback) throws IOException, UnsupportedCallbackException {
		if (callback instanceof PasswordValidationCallback) {
			PasswordValidationCallback passwordCallback = (PasswordValidationCallback) callback;
			if (passwordCallback.getRequest() instanceof PasswordValidationCallback.DigestPasswordRequest) {
				PasswordValidationCallback.DigestPasswordRequest request =
						(PasswordValidationCallback.DigestPasswordRequest) passwordCallback.getRequest();
				String username = request.getUsername();
				UserDetails user = loadUserDetails(username);
				if (user != null) {
					SpringSecurityUtils.checkUserValidity(user);
					request.setPassword(user.getPassword());
				}
				SpringSecurityDigestPasswordValidator validator = new SpringSecurityDigestPasswordValidator(user);
				passwordCallback.setValidator(validator);
				return;
			}
		}
		else if (callback instanceof TimestampValidationCallback) {
			TimestampValidationCallback timestampCallback = (TimestampValidationCallback) callback;
			timestampCallback.setValidator(new DefaultTimestampValidator());

		}
		else if (callback instanceof CleanupCallback) {
			SecurityContextHolder.clearContext();
			return;
		}
		throw new UnsupportedCallbackException(callback);
	}

	private UserDetails loadUserDetails(String username) throws DataAccessException {
		UserDetails user = userCache.getUserFromCache(username);

		if (user == null) {
			try {
				user = userDetailsService.loadUserByUsername(username);
			}
			catch (UsernameNotFoundException notFound) {
				if (logger.isDebugEnabled()) {
					logger.debug("Username '" + username + "' not found");
				}
				return null;
			}
			userCache.putUserInCache(user);
		}
		return user;
	}

	private class SpringSecurityDigestPasswordValidator extends PasswordValidationCallback.DigestPasswordValidator {

		private UserDetails user;

		private SpringSecurityDigestPasswordValidator(UserDetails user) {
			this.user = user;
		}

		@Override
		public boolean validate(PasswordValidationCallback.Request request)
				throws PasswordValidationCallback.PasswordValidationException {
			if (super.validate(request)) {
				UsernamePasswordAuthenticationToken authRequest =
						new UsernamePasswordAuthenticationToken(user, user.getPassword());
				if (logger.isDebugEnabled()) {
					logger.debug("Authentication success: " + authRequest.toString());
				}

				SecurityContextHolder.getContext().setAuthentication(authRequest);
				return true;
			}
			else {
				return false;
			}
		}
	}

}