/*
 * 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;

import org.springframework.context.MessageSource;
import org.springframework.context.MessageSourceAware;
import org.springframework.context.support.MessageSourceAccessor;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.AuthenticationException;
import org.springframework.security.core.SpringSecurityMessageSource;
import org.springframework.util.Assert;

/**
 * An {@link AuthenticationProvider} implementation that validates
 * {@link AnonymousAuthenticationToken}s.
 * <p>
 * To be successfully validated, the {@link AnonymousAuthenticationToken#getKeyHash()}
 * must match this class' {@link #getKey()}.
 *
 * @author Ben Alex
 */
public class AnonymousAuthenticationProvider implements AuthenticationProvider,
		MessageSourceAware {

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

	protected MessageSourceAccessor messages = SpringSecurityMessageSource.getAccessor();
	private String key;

	public AnonymousAuthenticationProvider(String key) {
		Assert.hasLength(key, "A Key is required");
		this.key = key;
	}

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

	public Authentication authenticate(Authentication authentication)
			throws AuthenticationException {
		if (!supports(authentication.getClass())) {
			return null;
		}

		if (this.key.hashCode() != ((AnonymousAuthenticationToken) authentication)
				.getKeyHash()) {
			throw new BadCredentialsException(
					messages.getMessage("AnonymousAuthenticationProvider.incorrectKey",
							"The presented AnonymousAuthenticationToken does not contain the expected key"));
		}

		return authentication;
	}

	public String getKey() {
		return key;
	}

	public void setMessageSource(MessageSource messageSource) {
		Assert.notNull(messageSource, "messageSource cannot be null");
		this.messages = new MessageSourceAccessor(messageSource);
	}

	public boolean supports(Class<?> authentication) {
		return (AnonymousAuthenticationToken.class.isAssignableFrom(authentication));
	}
}
