namespace Common.Hardware.Ports
{
    using System;

    public static partial class SerialPortExtensions
    {
        public const Byte UNIPRO_START = 0x53;
        public const Byte UNIPRO_PC2REG = 0x57;
        public const Byte UNIPRO_REG2PC = 0x52;
        public const Byte UNIPRO_STOP = 0x0D;
        public const Byte UNIPRO_MIN_LENGTH = 4;
        
        /// <summary>
        /// <para>UniPro structure:</para>
        /// <para>  0. .... - Start Byte</para>
        /// <para>  1. .... - Direction</para>
        /// <para>  2. .... - Length</para>
        /// <para>  .. .... - Payload</para>
        /// <para>n-1. .... - Stop Byte</para>
        /// </summary>
        public static Boolean TryParseToUniPro(this Byte[] data, out Byte[] bytes)
        {
            if (data is null)
            {
                data = new Byte[0];
            }

            var dataLength = data.Length;
            var bytesLength = dataLength + UNIPRO_MIN_LENGTH;

            bytes = new Byte[bytesLength];
            bytes[0] = UNIPRO_START;
            bytes[1] = UNIPRO_PC2REG;
            bytes[2] = (Byte)bytesLength;
            bytes[bytesLength - 1] = UNIPRO_STOP;

            Array.Copy(data, 0, bytes, 3, dataLength);

            return true;
        }

        /// <summary>
        /// <para>UniPro structure:</para>
        /// <para>  0. .... - Start Byte</para>
        /// <para>  1. .... - Direction</para>
        /// <para>  2. .... - Length</para>
        /// <para>  .. .... - Payload</para>
        /// <para>n-1. .... - Stop Byte</para>
        /// </summary>
        public static Boolean TryParseFromUniPro(this Byte[] bytes, out Byte[] data)
        {
            data = new Byte[0];

            if (bytes is null)
            {
                return false;
            }
            
            var start = Array.IndexOf(bytes, UNIPRO_START);

            if (start < 0)
            {
                return false;
            }

            var direction = Array.IndexOf(bytes, UNIPRO_REG2PC, start + 1);

            if (direction < 0)
            {
                return false;
            }

            var bytesLength = bytes.Length;
            var lengthIndex = direction + 1;

            if (lengthIndex >= bytesLength)
            {
                return false;
            }

            var dataIndex = lengthIndex + 1;

            if (dataIndex >= bytesLength)
            {
                return false;
            }

            var dataLength = bytes[lengthIndex] - UNIPRO_MIN_LENGTH;

            if (dataLength < 0 || dataIndex + dataLength > bytesLength)
            {
                return false;
            }
            
            data = new Byte[dataLength];

            Array.Copy(bytes, dataIndex, data, 0, dataLength);

            return true;
        }

        public const Byte IRDA_START = 0x9B;
        public const Byte IRDA_PING = 0x82;
        public const Byte IRDA_PC2REG = 0x33;
        public const Byte IRDA_REG2PC = 0x43;
        public const Byte IRDA_LEN_INDEX = 2;
        public const Byte IRDA_DATA_INDEX = 3;
        public const Byte IRDA_MIN_LENGTH = 5;

        /// <summary>
        /// <para>Irda structure:</para>
        /// <para>  0. .... - Start Byte</para>
        /// <para>  1. .... - Direction</para>
        /// <para>  2. .... - Length / 2</para>
        /// <para>3+n. .... - Payload</para>
        /// <para>n-3. .... - aligned Byte</para>
        /// <para>n-2. .... - CRC16 0 </para>
        /// <para>n-1. .... - CRC16 1 </para>
        /// </summary>
        public static Boolean TryParseToIrda(this Byte[] data, out Byte[] bytes)
        {
            bytes = new Byte[0];

            if (data is null)
            {
                data = new Byte[0];
            }

            var offset = data.Length % 2;
            var dataLength = data.Length + offset;
            var bytesLength = dataLength + IRDA_MIN_LENGTH;
            
            bytes = new Byte[bytesLength];
            bytes[0] = IRDA_START;
            bytes[1] = IRDA_PC2REG;
            bytes[2] = (Byte)(dataLength / 2);

            Array.Copy(data, 0, bytes, 3, data.Length);
            
            var crc = bytes.CalculateCRC8408(1, bytesLength - 2);
            bytes[bytesLength - 2] = crc[0];
            bytes[bytesLength - 1] = crc[1];

            return true;
        }

        /// <summary>
        /// <para>Irda structure:</para>
        /// <para>  0. .... - Start Byte</para>
        /// <para>  1. .... - Direction</para>
        /// <para>  2. .... - Length / 2</para>
        /// <para>3+n. .... - Payload</para>
        /// <para>n-3. .... - aligned Byte</para>
        /// <para>n-2. .... - CRC16 0 </para>
        /// <para>n-1. .... - CRC16 1 </para>
        /// </summary>
        public static Boolean TryParseFromIrda(this Byte[] bytes, out Byte[] data)
        {
            data = new Byte[0];

            if (bytes is null)
            {
                return false;
            }

            var bytesLength = bytes.Length;
            var directionIX = -1;
            var startIX = 0;

            while (bytesLength > startIX)
            {
                startIX = Array.IndexOf(bytes, IRDA_START, startIX);

                if (startIX < 0)
                {
                    break;
                }
                
                directionIX = Array.IndexOf(bytes, IRDA_REG2PC, ++startIX);
    
                if (directionIX > 0)
                {
                    break;
                }
                else
                {
                    directionIX = Array.IndexOf(bytes, (Byte)0x82, startIX++);

                    if (directionIX >= 0)
                    {
                        directionIX = -1;
                    }
                }
            }

            if (startIX < 0)
            {
                return false;
            }
            
            var lengthIndex = directionIX + 1;

            if (lengthIndex >= bytesLength)
            {
                return false;
            }

            var dataIndex = lengthIndex + 1;

            if (dataIndex >= bytesLength)
            {
                return false;
            }

            var dataLength = bytes[lengthIndex] * 2;

            if (dataIndex + dataLength > bytesLength)
            {
                return false;
            }

            data = new Byte[dataLength];

            Array.Copy(bytes, dataIndex, data, 0, dataLength);

            return true;
        }

        public const Byte UI1236_START = 0x0D;
        public const Byte UI1236_LEN_INDEX = 1;
        public const Byte UI1236_DATA_INDEX = 3;
        public const Byte UI1236_MIN_LENGTH = 5;

        /// <summary>
        /// <para>UI1236 structure:</para>
        /// <para>  0. 0x0D - Start Byte</para>
        /// <para>  1. .... - Length: max. 254</para>
        /// <para>  2. .... - Control Byte</para>
        /// <para>3+n. .... - Payload</para>
        /// <para>n-2. .... - Checksum 0 </para>
        /// <para>n-1. .... - Checksum 1 </para>
        /// </summary>
        public static Boolean TryParseToUI1236(this Byte[] data, out Byte[] bytes)
        {
            bytes = new Byte[0];

            if (data is null)
            {
                data = new Byte[0];
            }
            
            var dataLength = data.Length;
            var bytesLength = dataLength + UI1236_MIN_LENGTH;
            bytes = new Byte[bytesLength];
            bytes[0] = UI1236_START;
            bytes[1] = (Byte)(bytesLength - 2);

            UI1236Control control = 0;
            control.ReturnResponse = true;
            bytes[2] = control;

            Array.Copy(data, 0, bytes, 3, dataLength);
            
            var checksum = bytes.CalculateCheckSUM(bytes.Length - 2);
            bytes[bytesLength - 2] = checksum[1];
            bytes[bytesLength - 1] = checksum[0];

            return true;
        }

        /// <summary>
        /// <para>UI1236 structure:</para>
        /// <para>  0. 0x0D - Start Byte</para>
        /// <para>  1. .... - Length: max. 254</para>
        /// <para>  2. .... - Control Byte</para>
        /// <para>3+n. .... - Payload</para>
        /// <para>n-2. .... - Checksum 0 </para>
        /// <para>n-1. .... - Checksum 1 </para>
        /// </summary>
        public static Boolean TryParseFromUI1236(this Byte[] bytes, out Byte[] data)
        {
            data = new Byte[0];

            if (bytes is null)
            {
                return false;
            }

            var start = Array.IndexOf(bytes, UI1236_START);

            if (start < 0)
            {
                return false;
            }

            var bytesLength = bytes.Length;
            var lengthIndex = start + 1;

            if (lengthIndex >= bytesLength)
            {
                return false;
            }

            var dataIndex = lengthIndex + 2;

            if (dataIndex >= bytesLength)
            {
                return false;
            }

            var dataLength = bytes[lengthIndex] - 3; // 3 = protocol bytes length (start|control|length)

            if (dataIndex + dataLength > bytesLength)
            {
                return false;
            }

            data = new Byte[dataLength];

            Array.Copy(bytes, dataIndex, data, 0, dataLength);

            return true;
        }

        public static Byte[] CalculateCRC8408(this Byte[] bytes, Int32 start, Int32 length)
        {
            var crc = 0xFFFF;

            while (start < length)
            {
                crc ^= 0x00FF & bytes[start];

                for (var i = 8; i > 0; i--)
                {
                    if ((crc & 0x0001) != 0)
                    {
                        crc = (crc >> 1) ^ 0x8408;
                    }
                    else
                    {
                        crc >>= 1;
                    }
                }

                start++;
            }

            crc = ~crc;

            return BitConverter.GetBytes((UInt16)crc);
        }

        public static Byte[] CalculateCheckSUM(this Byte[] bytes, Int32 length)
        {
            UInt16 checksum = 0;

            for (var i = 0; i < length; i++)
            {
                checksum += bytes[i];
            }

            return BitConverter.GetBytes(checksum);
        }

        public static Byte[] CalculateCRC16(this Byte[] data, Int32 start, Int32 length)
        {
            var dataLength = data.Length;
            var maxLength = start + length;
            var crc = (UInt16)0xFFFF;

            Byte test;
            Byte current;

            if (data.Length > maxLength)
            {
                while (start < maxLength)
                {
                    current = data[start];

                    for (Byte h = 0; h < 8; h++)
                    {
                        test = 0;

                        if ((crc & 0x8000) != 0)
                        {
                            test = 0x80;
                        }

                        crc <<= 1;

                        if (((current & 0x80) ^ test) != 0)
                        {
                            crc ^= 0x1021;
                        }

                        current <<= 1;
                    }

                    start++;
                }
            }

            return BitConverter.GetBytes(crc);
        }

        public static Byte[] CalculateCRC1021(this Byte[] bytes, Int32 start, Int32 length)
        {
            UInt16 crcSum = 0xFFFF;

            while (start < length)
            {
                var @byte = bytes[start];

                for (int bit = 0; bit < 8; bit++)
                {
                    var test = default(Byte);

                    if ((crcSum & 0x8000) != 0)
                    {
                        test = 0x80;
                    }

                    crcSum <<= 1;

                    if (((@byte & 0x80) ^ test) != 0)
                    {
                        crcSum ^= 0x1021;
                    }

                    @byte <<= 1;
                }

                start++;
            }

            return BitConverter.GetBytes(crcSum);
        }
    }
}