/**
 * This file is part of Graylog.
 *
 * Graylog is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Graylog is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Graylog.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.graylog2.security.realm;

import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationInfo;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.authc.UsernamePasswordToken;
import org.apache.shiro.realm.AuthenticatingRealm;
import org.apache.shiro.util.ByteSource;
import org.graylog2.plugin.database.users.User;
import org.graylog2.shared.users.UserService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.inject.Inject;
import javax.inject.Named;

/**
 * @author Kay Roepke <kay@torch.sh>
 */
public class PasswordAuthenticator extends AuthenticatingRealm {
    private static final Logger LOG = LoggerFactory.getLogger(PasswordAuthenticator.class);
    public static final String NAME = "mongodb-password";
    private final UserService userService;
    private ByteSource credentialsSalt;

    @Inject
    PasswordAuthenticator(UserService userService,
                          @Named("password_secret") String passwordSecret,
                          PasswordAlgorithmCredentialsMatcher passwordAlgorithmCredentialsMatcher) {
        this.userService = userService;
        credentialsSalt = ByteSource.Util.bytes(passwordSecret);
        setCachingEnabled(false);
        setCredentialsMatcher(passwordAlgorithmCredentialsMatcher);
    }

    @Override
    protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken authToken) throws AuthenticationException {
        UsernamePasswordToken token = (UsernamePasswordToken) authToken;
        LOG.debug("Retrieving authc info for user {}", token.getUsername());

        final User user = userService.load(token.getUsername());
        if (user == null || user.isLocalAdmin()) {
            // skip the local admin user here, it's ugly, but for auth that user is treated specially.
            return null;
        }
        if (user.isExternalUser()) {
            // we don't store passwords for LDAP users, so we can't handle them here.
            LOG.trace("Skipping mongodb-based password check for LDAP user {}", token.getUsername());
            return null;
        }

        if (LOG.isDebugEnabled()) {
            LOG.debug("Found user {} to be authenticated with password.", user.getName());
        }
        return new UserAccount(token.getPrincipal(),
                               user.getHashedPassword(),
                               credentialsSalt,
                               "graylog2MongoDbRealm",
                               user);
    }
}