/**
 * 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.hashing;

import org.graylog2.plugin.security.PasswordAlgorithm;
import org.mindrot.jbcrypt.BCrypt;

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

import static com.google.common.base.Preconditions.checkArgument;

public class BCryptPasswordAlgorithm implements PasswordAlgorithm {
    private static final String PREFIX = "{bcrypt}";
    private static final String SALT_PREFIX = "{salt}";

    private final Integer saltSize;

    @Inject
    public BCryptPasswordAlgorithm(@Named("user_password_bcrypt_salt_size") Integer saltSize) {
        this.saltSize = saltSize;
    }

    @Override
    public boolean supports(String hashedPassword) {
        return hashedPassword.startsWith(PREFIX) && hashedPassword.contains(SALT_PREFIX);
    }

    private String hash(String password, String salt) {
        return PREFIX + BCrypt.hashpw(password, salt) + SALT_PREFIX + salt;
    }

    @Override
    public String hash(String password) {
        return hash(password, BCrypt.gensalt(this.saltSize));
    }

    @Override
    public boolean matches(String hashedPasswordAndSalt, String otherPassword) {
        checkArgument(supports(hashedPasswordAndSalt), "Supplied hashed password is not supported, it does not start with "
                + PREFIX + " or does not contain a salt.");

        final int saltIndex = hashedPasswordAndSalt.lastIndexOf(SALT_PREFIX);
        final String salt = hashedPasswordAndSalt.substring(saltIndex + SALT_PREFIX.length());
        return hash(otherPassword, salt).equals(hashedPasswordAndSalt);
    }
}