/* 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.authentication.dao;

import org.springframework.security.authentication.AuthenticationProvider;
import org.springframework.security.authentication.AuthenticationServiceException;
import org.springframework.security.authentication.BadCredentialsException;
import org.springframework.security.authentication.InternalAuthenticationServiceException;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.authentication.encoding.PasswordEncoder;
import org.springframework.security.authentication.encoding.PlaintextPasswordEncoder;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.util.Assert;

/**
 * An {@link AuthenticationProvider} implementation that retrieves user details from a
 * {@link UserDetailsService}.
 *
 * @author Ben Alex
 * @author Rob Winch
 */
public class DaoAuthenticationProvider extends AbstractUserDetailsAuthenticationProvider {
	// ~ Static fields/initializers
	// =====================================================================================

	/**
	 * The plaintext password used to perform
	 * {@link PasswordEncoder#isPasswordValid(String, String, Object)} on when the user is
	 * not found to avoid SEC-2056.
	 */
	private static final String USER_NOT_FOUND_PASSWORD = "userNotFoundPassword";

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

	private PasswordEncoder passwordEncoder;

	/**
	 * The password used to perform
	 * {@link PasswordEncoder#isPasswordValid(String, String, Object)} on when the user is
	 * not found to avoid SEC-2056. This is necessary, because some
	 * {@link PasswordEncoder} implementations will short circuit if the password is not
	 * in a valid format.
	 */
	private String userNotFoundEncodedPassword;

	private SaltSource saltSource;

	private UserDetailsService userDetailsService;

	public DaoAuthenticationProvider() {
		setPasswordEncoder(new PlaintextPasswordEncoder());
	}

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

	@SuppressWarnings("deprecation")
	protected void additionalAuthenticationChecks(UserDetails userDetails,
			UsernamePasswordAuthenticationToken authentication)
			throws AuthenticationException {
		Object salt = null;

		if (this.saltSource != null) {
			salt = this.saltSource.getSalt(userDetails);
		}

		if (authentication.getCredentials() == null) {
			logger.debug("Authentication failed: no credentials provided");

			throw new BadCredentialsException(messages.getMessage(
					"AbstractUserDetailsAuthenticationProvider.badCredentials",
					"Bad credentials"));
		}

		String presentedPassword = authentication.getCredentials().toString();

		if (!passwordEncoder.isPasswordValid(userDetails.getPassword(),
				presentedPassword, salt)) {
			logger.debug("Authentication failed: password does not match stored value");

			throw new BadCredentialsException(messages.getMessage(
					"AbstractUserDetailsAuthenticationProvider.badCredentials",
					"Bad credentials"));
		}
	}

	protected void doAfterPropertiesSet() throws Exception {
		Assert.notNull(this.userDetailsService, "A UserDetailsService must be set");
	}

	protected final UserDetails retrieveUser(String username,
			UsernamePasswordAuthenticationToken authentication)
			throws AuthenticationException {
		UserDetails loadedUser;

		try {
			loadedUser = this.getUserDetailsService().loadUserByUsername(username);
		}
		catch (UsernameNotFoundException notFound) {
			if (authentication.getCredentials() != null) {
				String presentedPassword = authentication.getCredentials().toString();
				passwordEncoder.isPasswordValid(userNotFoundEncodedPassword,
						presentedPassword, null);
			}
			throw notFound;
		}
		catch (Exception repositoryProblem) {
			throw new InternalAuthenticationServiceException(
					repositoryProblem.getMessage(), repositoryProblem);
		}

		if (loadedUser == null) {
			throw new InternalAuthenticationServiceException(
					"UserDetailsService returned null, which is an interface contract violation");
		}
		return loadedUser;
	}

	/**
	 * Sets the PasswordEncoder instance to be used to encode and validate passwords. If
	 * not set, the password will be compared as plain text.
	 * <p>
	 * For systems which are already using salted password which are encoded with a
	 * previous release, the encoder should be of type
	 * {@code org.springframework.security.authentication.encoding.PasswordEncoder}.
	 * Otherwise, the recommended approach is to use
	 * {@code org.springframework.security.crypto.password.PasswordEncoder}.
	 *
	 * @param passwordEncoder must be an instance of one of the {@code PasswordEncoder}
	 * types.
	 */
	public void setPasswordEncoder(Object passwordEncoder) {
		Assert.notNull(passwordEncoder, "passwordEncoder cannot be null");

		if (passwordEncoder instanceof PasswordEncoder) {
			setPasswordEncoder((PasswordEncoder) passwordEncoder);
			return;
		}

		if (passwordEncoder instanceof org.springframework.security.crypto.password.PasswordEncoder) {
			final org.springframework.security.crypto.password.PasswordEncoder delegate = (org.springframework.security.crypto.password.PasswordEncoder) passwordEncoder;
			setPasswordEncoder(new PasswordEncoder() {
				public String encodePassword(String rawPass, Object salt) {
					checkSalt(salt);
					return delegate.encode(rawPass);
				}

				public boolean isPasswordValid(String encPass, String rawPass, Object salt) {
					checkSalt(salt);
					return delegate.matches(rawPass, encPass);
				}

				private void checkSalt(Object salt) {
					Assert.isNull(salt,
							"Salt value must be null when used with crypto module PasswordEncoder");
				}
			});

			return;
		}

		throw new IllegalArgumentException(
				"passwordEncoder must be a PasswordEncoder instance");
	}

	private void setPasswordEncoder(PasswordEncoder passwordEncoder) {
		Assert.notNull(passwordEncoder, "passwordEncoder cannot be null");

		this.userNotFoundEncodedPassword = passwordEncoder.encodePassword(
				USER_NOT_FOUND_PASSWORD, null);
		this.passwordEncoder = passwordEncoder;
	}

	protected PasswordEncoder getPasswordEncoder() {
		return passwordEncoder;
	}

	/**
	 * The source of salts to use when decoding passwords. <code>null</code> is a valid
	 * value, meaning the <code>DaoAuthenticationProvider</code> will present
	 * <code>null</code> to the relevant <code>PasswordEncoder</code>.
	 * <p>
	 * Instead, it is recommended that you use an encoder which uses a random salt and
	 * combines it with the password field. This is the default approach taken in the
	 * {@code org.springframework.security.crypto.password} package.
	 *
	 * @param saltSource to use when attempting to decode passwords via the
	 * <code>PasswordEncoder</code>
	 */
	public void setSaltSource(SaltSource saltSource) {
		this.saltSource = saltSource;
	}

	protected SaltSource getSaltSource() {
		return saltSource;
	}

	public void setUserDetailsService(UserDetailsService userDetailsService) {
		this.userDetailsService = userDetailsService;
	}

	protected UserDetailsService getUserDetailsService() {
		return userDetailsService;
	}
}
