namespace Common.Hardware.SIRT
{
    using Common.Hardware.Ports;
    using Newtonsoft.Json;
    using System;

    public class SIRTMessage
    {
        public const byte MIN_LEN = 12;
        public const byte PC2SIRT = 0x55;
        public const byte SIRT2PC = 0xFF;
        public const byte W_PAM = 0x81;
        public const byte R_PAM = 0x82;
        public const byte W_REG = 0x84;
        public const byte R_REG = 0x87;
        public const byte FROMAIR = 0x11;
        public const byte ACKNANSW = 0x12;
        public const byte STOP = 0x16;
        public const byte BUP = 0x00;
        public const byte LAT = 0x01;
        public const byte DEBUG = 0x0B;
        public const byte SEMI = 0x08;

        private byte[] bytes;

        public SIRTMessage()
        {
            this.bytes = new byte[MIN_LEN];
            this.bytes[0] = PC2SIRT;
        }

        public SIRTMessage(byte[] bytes)
        {
            this.bytes = bytes;
            this.bytes[0] = SIRT2PC;
        }

        public byte Cmd
        {
            get => this.bytes[1];
            set => this.bytes[1] = value;
        }

        public byte P1
        {
            get => this.bytes[2];
            set => this.bytes[2] = value;
        }

        public byte P2
        {
            get => this.bytes[3];
            set => this.bytes[3] = value;
        }

        public uint Address
        {
            get => this.bytes.ToUInt32BE(4);
            set => value.GetBytesBE().CopyTo(this.bytes, 4);
        }

        public byte Length => this.bytes[8];

        [JsonIgnore]
        public byte[] Data
        {
            get
            {
                var data = new byte[this.Length];

                Array.Copy(this.bytes, 9, data, 0, this.Length);

                return data;
            }
            set
            {
                if (value is null)
                {
                    value = new byte[0];
                }

                this.bytes[8] = (byte)value.Length;

                Array.Resize(ref this.bytes, MIN_LEN + this.Length);
                Array.Clear(this.bytes, 9, this.bytes.Length - 9);
                Array.Copy(value, 0, this.bytes, 9, this.Length);
            }
        }

        public ushort CRC => this.bytes.ToUInt16BE(this.bytes.Length - 3);

        public string Content => this.ToString();

        public byte[] ToByteArray()
        {
            var length = this.bytes.Length;
            var crc = this.bytes.CRCCCITT(1, length - 3);
            var crcBytes = crc.GetBytesBE();

            this.bytes[length - 3] = crcBytes[0];
            this.bytes[length - 2] = crcBytes[1];
            this.bytes[length - 1] = STOP;

            return this.bytes;
        }

        public override string ToString()
            => BitConverter.ToString(this.ToByteArray());
    }
}