/**
 * Copyright (c) 2010-2022 Contributors to the openHAB project
 *
 * See the NOTICE file(s) distributed with this work for additional
 * information.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0
 *
 * SPDX-License-Identifier: EPL-2.0
 */
package org.openhab.binding.enocean.internal.messages;

import org.openhab.binding.enocean.internal.EnOceanException;

/**
 *
 * @author Daniel Weber - Initial contribution
 */
public class ESP3Packet {

    private static byte[] crc8_table = new byte[] { (byte) 0x00, (byte) 0x07, (byte) 0x0e, (byte) 0x09, (byte) 0x1c,
            (byte) 0x1b, (byte) 0x12, (byte) 0x15, (byte) 0x38, (byte) 0x3f, (byte) 0x36, (byte) 0x31, (byte) 0x24,
            (byte) 0x23, (byte) 0x2a, (byte) 0x2d, (byte) 0x70, (byte) 0x77, (byte) 0x7e, (byte) 0x79, (byte) 0x6c,
            (byte) 0x6b, (byte) 0x62, (byte) 0x65, (byte) 0x48, (byte) 0x4f, (byte) 0x46, (byte) 0x41, (byte) 0x54,
            (byte) 0x53, (byte) 0x5a, (byte) 0x5d, (byte) 0xe0, (byte) 0xe7, (byte) 0xee, (byte) 0xe9, (byte) 0xfc,
            (byte) 0xfb, (byte) 0xf2, (byte) 0xf5, (byte) 0xd8, (byte) 0xdf, (byte) 0xd6, (byte) 0xd1, (byte) 0xc4,
            (byte) 0xc3, (byte) 0xca, (byte) 0xcd, (byte) 0x90, (byte) 0x97, (byte) 0x9e, (byte) 0x99, (byte) 0x8c,
            (byte) 0x8b, (byte) 0x82, (byte) 0x85, (byte) 0xa8, (byte) 0xaf, (byte) 0xa6, (byte) 0xa1, (byte) 0xb4,
            (byte) 0xb3, (byte) 0xba, (byte) 0xbd, (byte) 0xc7, (byte) 0xc0, (byte) 0xc9, (byte) 0xce, (byte) 0xdb,
            (byte) 0xdc, (byte) 0xd5, (byte) 0xd2, (byte) 0xff, (byte) 0xf8, (byte) 0xf1, (byte) 0xf6, (byte) 0xe3,
            (byte) 0xe4, (byte) 0xed, (byte) 0xea, (byte) 0xb7, (byte) 0xb0, (byte) 0xb9, (byte) 0xbe, (byte) 0xab,
            (byte) 0xac, (byte) 0xa5, (byte) 0xa2, (byte) 0x8f, (byte) 0x88, (byte) 0x81, (byte) 0x86, (byte) 0x93,
            (byte) 0x94, (byte) 0x9d, (byte) 0x9a, (byte) 0x27, (byte) 0x20, (byte) 0x29, (byte) 0x2e, (byte) 0x3b,
            (byte) 0x3c, (byte) 0x35, (byte) 0x32, (byte) 0x1f, (byte) 0x18, (byte) 0x11, (byte) 0x16, (byte) 0x03,
            (byte) 0x04, (byte) 0x0d, (byte) 0x0a, (byte) 0x57, (byte) 0x50, (byte) 0x59, (byte) 0x5e, (byte) 0x4b,
            (byte) 0x4c, (byte) 0x45, (byte) 0x42, (byte) 0x6f, (byte) 0x68, (byte) 0x61, (byte) 0x66, (byte) 0x73,
            (byte) 0x74, (byte) 0x7d, (byte) 0x7a, (byte) 0x89, (byte) 0x8e, (byte) 0x87, (byte) 0x80, (byte) 0x95,
            (byte) 0x92, (byte) 0x9b, (byte) 0x9c, (byte) 0xb1, (byte) 0xb6, (byte) 0xbf, (byte) 0xb8, (byte) 0xad,
            (byte) 0xaa, (byte) 0xa3, (byte) 0xa4, (byte) 0xf9, (byte) 0xfe, (byte) 0xf7, (byte) 0xf0, (byte) 0xe5,
            (byte) 0xe2, (byte) 0xeb, (byte) 0xec, (byte) 0xc1, (byte) 0xc6, (byte) 0xcf, (byte) 0xc8, (byte) 0xdd,
            (byte) 0xda, (byte) 0xd3, (byte) 0xd4, (byte) 0x69, (byte) 0x6e, (byte) 0x67, (byte) 0x60, (byte) 0x75,
            (byte) 0x72, (byte) 0x7b, (byte) 0x7c, (byte) 0x51, (byte) 0x56, (byte) 0x5f, (byte) 0x58, (byte) 0x4d,
            (byte) 0x4a, (byte) 0x43, (byte) 0x44, (byte) 0x19, (byte) 0x1e, (byte) 0x17, (byte) 0x10, (byte) 0x05,
            (byte) 0x02, (byte) 0x0b, (byte) 0x0c, (byte) 0x21, (byte) 0x26, (byte) 0x2f, (byte) 0x28, (byte) 0x3d,
            (byte) 0x3a, (byte) 0x33, (byte) 0x34, (byte) 0x4e, (byte) 0x49, (byte) 0x40, (byte) 0x47, (byte) 0x52,
            (byte) 0x55, (byte) 0x5c, (byte) 0x5b, (byte) 0x76, (byte) 0x71, (byte) 0x78, (byte) 0x7f, (byte) 0x6A,
            (byte) 0x6d, (byte) 0x64, (byte) 0x63, (byte) 0x3e, (byte) 0x39, (byte) 0x30, (byte) 0x37, (byte) 0x22,
            (byte) 0x25, (byte) 0x2c, (byte) 0x2b, (byte) 0x06, (byte) 0x01, (byte) 0x08, (byte) 0x0f, (byte) 0x1a,
            (byte) 0x1d, (byte) 0x14, (byte) 0x13, (byte) 0xae, (byte) 0xa9, (byte) 0xa0, (byte) 0xa7, (byte) 0xb2,
            (byte) 0xb5, (byte) 0xbc, (byte) 0xbb, (byte) 0x96, (byte) 0x91, (byte) 0x98, (byte) 0x9f, (byte) 0x8a,
            (byte) 0x8D, (byte) 0x84, (byte) 0x83, (byte) 0xde, (byte) 0xd9, (byte) 0xd0, (byte) 0xd7, (byte) 0xc2,
            (byte) 0xc5, (byte) 0xcc, (byte) 0xcb, (byte) 0xe6, (byte) 0xe1, (byte) 0xe8, (byte) 0xef, (byte) 0xfa,
            (byte) 0xfd, (byte) 0xf4, (byte) 0xf3 };

    public static final int ESP3_HEADER_LENGTH = 4;
    private static final int ESP3_SYNC_BYTE_LENGTH = 1;
    private static final int ESP3_CRC3_HEADER_LENGTH = 1;
    private static final int ESP3_CRC8_DATA_LENGTH = 1;

    public static final int ESP3_RORG_LENGTH = 1;
    public static final int ESP3_SENDERID_LENGTH = 4;
    public static final int ESP3_STATUS_LENGTH = 1;

    public static final byte ESP3_SYNC_BYTE = 0x55;

    protected BasePacket basePacket;

    public ESP3Packet(BasePacket basePacket) {
        this.basePacket = basePacket;
    }

    private byte calcCRC8(byte data[], int offset, int length) {
        byte output = 0;
        for (int i = offset; i < offset + length; i++) {
            int index = (output ^ data[i]) & 0xff;
            output = crc8_table[index];
        }
        return (byte) (output & 0xff);
    }

    public byte[] serialize() throws EnOceanException {
        try {
            byte[] payload = basePacket.getPayload();
            byte[] optionalPayload = basePacket.getOptionalPayload();

            int optionalLength = optionalPayload != null ? optionalPayload.length : 0;

            byte[] result = new byte[ESP3_SYNC_BYTE_LENGTH + ESP3_HEADER_LENGTH + ESP3_CRC3_HEADER_LENGTH
                    + payload.length + optionalLength + ESP3_CRC8_DATA_LENGTH];

            result[0] = ESP3_SYNC_BYTE;
            result[1] = (byte) ((payload.length >> 8) & 0xff);
            result[2] = (byte) (payload.length & 0xff);
            result[3] = (byte) (optionalLength & 0xff);
            result[4] = basePacket.getPacketType().getValue();
            result[5] = calcCRC8(result, ESP3_SYNC_BYTE_LENGTH, ESP3_HEADER_LENGTH);
            for (int i = 0; i < payload.length; i++) {
                result[6 + i] = payload[i];
            }
            if (optionalPayload != null) {
                for (int i = 0; i < optionalPayload.length; i++) {
                    result[6 + payload.length + i] = (byte) (optionalPayload[i] & 0xff);
                }
            }
            result[6 + payload.length + optionalLength] = calcCRC8(result, 6, payload.length + optionalLength);

            return result;
        } catch (Exception e) {
            throw new EnOceanException(e.getMessage());
        }
    }

    public static boolean checkCRC8(byte data[], int length, byte crc8) {
        byte output = 0;
        for (int i = 0; i < length; i++) {
            int index = (output ^ data[i]) & 0xff;
            output = crc8_table[index];
        }
        return output == crc8;
    }
}
