/*
 * Copyright (c) 2012, 2023, Oracle and/or its affiliates.
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, version 2.0, as published by the
 * Free Software Foundation.
 *
 * This program is also distributed with certain software (including but not
 * limited to OpenSSL) that is licensed under separate terms, as designated in a
 * particular file or component or in included license documentation. The
 * authors of MySQL hereby grant you an additional permission to link the
 * program and your derivative works with the separately licensed software that
 * they have included with MySQL.
 *
 * Without limiting anything contained in the foregoing, this file, which is
 * part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
 * version 1.0, a copy of which can be found at
 * http://oss.oracle.com/licenses/universal-foss-exception.
 *
 * This program 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, version 2.0,
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
 */

package com.mysql.cj.protocol.a.authentication;

import java.io.UnsupportedEncodingException;
import java.util.List;

import com.mysql.cj.callback.MysqlCallbackHandler;
import com.mysql.cj.callback.UsernameCallback;
import com.mysql.cj.protocol.AuthenticationPlugin;
import com.mysql.cj.protocol.Protocol;
import com.mysql.cj.protocol.a.NativeConstants.IntegerDataType;
import com.mysql.cj.protocol.a.NativeConstants.StringSelfDataType;
import com.mysql.cj.protocol.a.NativePacketPayload;
import com.mysql.cj.util.StringUtils;

/**
 * MySQL Native Old-Password Authentication Plugin
 */
public class MysqlOldPasswordPlugin implements AuthenticationPlugin<NativePacketPayload> {

    public static String PLUGIN_NAME = "mysql_old_password";

    private Protocol<NativePacketPayload> protocol = null;
    private MysqlCallbackHandler usernameCallbackHandler = null;
    private String password = null;

    @Override
    public void init(Protocol<NativePacketPayload> prot, MysqlCallbackHandler cbh) {
        this.protocol = prot;
        this.usernameCallbackHandler = cbh;
    }

    @Override
    public void destroy() {
        reset();
        this.protocol = null;
        this.usernameCallbackHandler = null;
        this.password = null;
    }

    @Override
    public String getProtocolPluginName() {
        return PLUGIN_NAME;
    }

    @Override
    public boolean requiresConfidentiality() {
        return false;
    }

    @Override
    public boolean isReusable() {
        return true;
    }

    @Override
    public void setAuthenticationParameters(String user, String password) {
        this.password = password;
        if (user == null && this.usernameCallbackHandler != null) {
            // Fall back to system login user.
            this.usernameCallbackHandler.handle(new UsernameCallback(System.getProperty("user.name")));
        }
    }

    @Override
    public boolean nextAuthenticationStep(NativePacketPayload fromServer, List<NativePacketPayload> toServer) {
        toServer.clear();

        NativePacketPayload packet = null;

        String pwd = this.password;

        if (fromServer == null || pwd == null || pwd.length() == 0) {
            packet = new NativePacketPayload(new byte[0]);
        } else {
            packet = new NativePacketPayload(StringUtils.getBytes(newCrypt(pwd, fromServer.readString(StringSelfDataType.STRING_TERM, null).substring(0, 8),
                    this.protocol.getServerSession().getCharsetSettings().getPasswordCharacterEncoding())));

            packet.setPosition(packet.getPayloadLength());
            packet.writeInteger(IntegerDataType.INT1, 0);
            packet.setPosition(0);
        }
        toServer.add(packet);

        return true;
    }

    // Right from Monty's code
    private static String newCrypt(String password, String seed, String encoding) {
        byte b;
        double d;

        if (password == null || password.length() == 0) {
            return password;
        }

        long[] pw = newHash(seed.getBytes());
        long[] msg = hashPre41Password(password, encoding);
        long max = 0x3fffffffL;
        long seed1 = (pw[0] ^ msg[0]) % max;
        long seed2 = (pw[1] ^ msg[1]) % max;
        char[] chars = new char[seed.length()];

        for (int i = 0; i < seed.length(); i++) {
            seed1 = (seed1 * 3 + seed2) % max;
            seed2 = (seed1 + seed2 + 33) % max;
            d = (double) seed1 / (double) max;
            b = (byte) java.lang.Math.floor(d * 31 + 64);
            chars[i] = (char) b;
        }

        seed1 = (seed1 * 3 + seed2) % max;
        seed2 = (seed1 + seed2 + 33) % max;
        d = (double) seed1 / (double) max;
        b = (byte) java.lang.Math.floor(d * 31);

        for (int i = 0; i < seed.length(); i++) {
            chars[i] ^= (char) b;
        }

        return new String(chars);
    }

    private static long[] hashPre41Password(String password, String encoding) {
        // remove white spaces and convert to bytes
        try {
            return newHash(password.replaceAll("\\s", "").getBytes(encoding));
        } catch (UnsupportedEncodingException e) {
            return new long[0];
        }
    }

    private static long[] newHash(byte[] password) {
        long nr = 1345345333L;
        long add = 7;
        long nr2 = 0x12345671L;
        long tmp;

        for (byte b : password) {
            tmp = 0xff & b;
            nr ^= ((nr & 63) + add) * tmp + (nr << 8);
            nr2 += nr2 << 8 ^ nr;
            add += tmp;
        }

        long[] result = new long[2];
        result[0] = nr & 0x7fffffffL;
        result[1] = nr2 & 0x7fffffffL;

        return result;
    }

}
