/*

 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.math.BigInteger;

import java.util.Arrays;

import java.util.Optional;

import java.util.stream.Stream;

/**

 * Class to present one Ldap message.

 */

public class LdapMessage {

    private final byte[] messages;

    private int messageID;

    private Operation operation;

    public enum Operation {

        BIND_REQUEST(0x60, "BindRequest"), // [APPLICATION 0]

        BIND_RESPONSE(0x61, "BindResponse"), // [APPLICATION 1]

        UNBIND_REQUEST(0x42, "UnbindRequest"), // [APPLICATION 2]

        SEARCH_REQUEST(0x63, "SearchRequest"), // [APPLICATION 3]

        SEARCH_RESULT_ENTRY(0x64, "SearchResultEntry"), // [APPLICATION 4]

        SEARCH_RESULT_DONE(0x65, "SearchResultDone"), // [APPLICATION 5]

        MODIFY_REQUEST(0x66, "ModifyRequest"), // [APPLICATION 6]

        MODIFY_RESPONSE(0x67, "ModifyResponse"), // [APPLICATION 7]

        ADD_REQUEST(0x68, "AddRequest"), // [APPLICATION 8]

        ADD_RESPONSE(0x69, "AddResponse"), // [APPLICATION 9]

        DELETE_REQUEST(0x4A, "DeleteRequest"), // [APPLICATION 10]

        DELETE_RESPONSE(0x6B, "DeleteResponse"), // [APPLICATION 11]

        MODIFY_DN_REQUEST(0x6C, "ModifyDNRequest"), // [APPLICATION 12]

        MODIFY_DN_RESPONSE(0x6D, "ModifyDNResponse"), // [APPLICATION 13]

        COMPARE_REQUEST(0x6E, "CompareRequest"), // [APPLICATION 14]

        COMPARE_RESPONSE(0x6F, "CompareResponse"), // [APPLICATION 15]

        ABANDON_REQUEST(0x50, "AbandonRequest"), // [APPLICATION 16]

        SEARCH_RESULT_REFERENCE(0x73,

                "SearchResultReference"), // [APPLICATION 19]

        EXTENDED_REQUEST(0x77, "ExtendedRequest"), // [APPLICATION 23]

        EXTENDED_RESPONSE(0x78, "ExtendedResponse"), // [APPLICATION 24]

        INTERMEDIATE_RESPONSE(0x79, "IntermediateResponse"); // [APPLICATION 25]

        private final int id;

        private final String name;

        Operation(int id, String name) {

            this.id = id;

            this.name = name;

        }

        public int getId() {

            return id;

        }

        @Override

        public String toString() {

            return name;

        }

        public static Operation fromId(int id) {

            Optional<Operation> optional = Stream.of(Operation.values())

                    .filter(o -> o.id == id).findFirst();

            if (optional.isPresent()) {

                return optional.get();

            } else {

                throw new RuntimeException(

                        "Unknown id " + id + " for enum Operation.");

            }

        }

    }

    public LdapMessage(byte[] messages) {

        this.messages = messages;

        parse();

    }

    public LdapMessage(String hexString) {

        this(parseHexBinary(hexString));

    }

    // Extracts the message ID and operation ID from an LDAP protocol encoding

    private void parse() {

        if (messages == null || messages.length < 2) {

            throw new RuntimeException(

                    "Invalid ldap messages: " + Arrays.toString(messages));

        }

        if (messages[0] != 0x30) {

            throw new RuntimeException("Bad LDAP encoding in messages, "

                    + "expected ASN.1 SEQUENCE tag (0x30), encountered "

                    + messages[0]);

        }

        int index = 2;

        if ((messages[1] & 0x80) == 0x80) {

            index += (messages[1] & 0x0F);

        }

        if (messages[index] != 0x02) {

            throw new RuntimeException("Bad LDAP encoding in messages, "

                    + "expected ASN.1 INTEGER tag (0x02), encountered "

                    + messages[index]);

        }

        int length = messages[index + 1];

        index += 2;

        messageID = new BigInteger(1,

                Arrays.copyOfRange(messages, index, index + length)).intValue();

        index += length;

        int operationID = messages[index];

        operation = Operation.fromId(operationID);

    }

    /**

     * Return original ldap message in byte array.

     *

     * @return original ldap message

     */

    public byte[] getMessages() {

        return Arrays.copyOf(messages, messages.length);

    }

    /**

     * Return ldap message id.

     *

     * @return ldap message id.

     */

    public int getMessageID() {

        return messageID;

    }

    /**

     * Return ldap message's operation.

     *

     * @return ldap message's operation.

     */

    public Operation getOperation() {

        return operation;

    }

    private static byte[] parseHexBinary(String s) {

        final int len = s.length();

        // "111" is not a valid hex encoding.

        if (len % 2 != 0) {

            throw new IllegalArgumentException(

                    "hexBinary needs to be even-length: " + s);

        }

        byte[] out = new byte[len / 2];

        for (int i = 0; i < len; i += 2) {

            int h = hexToBin(s.charAt(i));

            int l = hexToBin(s.charAt(i + 1));

            if (h == -1 || l == -1) {

                throw new IllegalArgumentException(

                        "contains illegal character for hexBinary: " + s);

            }

            out[i / 2] = (byte) (h * 16 + l);

        }

        return out;

    }

    private static int hexToBin(char ch) {

        if ('0' <= ch && ch <= '9') {

            return ch - '0';

        }

        if ('A' <= ch && ch <= 'F') {

            return ch - 'A' + 10;

        }

        if ('a' <= ch && ch <= 'f') {

            return ch - 'a' + 10;

        }

        return -1;

    }

}