SafeDispatch/LibrarySDR/Requests/PollSDSRequest.cs

using LibrarySDR.Enums;
using LibrarySDR.Flags;
using System;
using System.Globalization;
using System.Text;
using static LibrarySDR.Helpers.BinaryHexHelper;

namespace LibrarySDR.Requests
{
    public class PollSDSRequest
    {
        private static int sendingReference = 0;
        public static int SendingReference
        {
            get
            {
                // rest counter to value 0 after max value inside a byte
                if (sendingReference > 255)
                    sendingReference = 0;

                return sendingReference;
            }
        }

        private static PDUType PduType = PDUType.DATA_REQ_RESP;
        private static ProtocolIdentifier protocolIdentifier = ProtocolIdentifier.SimpleTextWithoutSDSTL;

        private Int64 sourceISSI;
        public Int64 SourceISSI { get { return sourceISSI; } }

        private Int64 destinationISSI;
        public Int64 DestinationISSI { get { return destinationISSI; } }


        private ProtocolIdentifier pi;
        public ProtocolIdentifier ProtocolIdentifier { get { return pi; } }

        private Int16 messageReference;
        public Int16 MessageRefence { get { return messageReference;  } }

        private Int16 areaSelection;
        public Int16 AreaSelection { get { return areaSelection; } }

        private Int16 validityPeriod;
        public Int16 ValidityPeriod { get { return validityPeriod; } }


        private Int64 forwardAddress;
        public Int64 ForwardAddress { get { return forwardAddress; } }

        private Int16 flags;
        public Int16 Flags { get { return flags; } }

        private DataFlag dataFlag;
        public DataFlag DataFlags { get { return dataFlag; } }

        private Int16 lengthBits;
        public Int16 LengthBits { get { return lengthBits; } }

        private Int16 lengthBytes;
        public Int16 LengthBytes { get { return lengthBytes; } }
        
        private String message;
        public String Message { get { return message; } }


        private String hexMessage;
        public String HexMessage { get { return hexMessage; } }

        private static Int64 transactionId = 1;
        public static Int64 TransactionId
        {
            get
            {
                return transactionId++;
            }
        }
       
        public static String GetInstance(Int64 sourceISSI, Int64 destinationISSI, String text, bool isConfirmationReq)
        {
            StringBuilder sb = new StringBuilder("");

            // PDU Type (8 bits)
            sb.Append(GetBits((int)PduType, 8));

            // Source ISSI (32 bits)
            sb.Append(GetBits(sourceISSI, 32));

            // Destination ISSI (32 bits)
            sb.Append(GetBits(destinationISSI, 32));

            // Protocol Identifier (8 bits)
            bool Hytera = false;
            sb.Append(GetBits(Hytera ? (int)ProtocolIdentifier.GPS : (int)ProtocolIdentifier.GPS, 8));

            // Message reference (8 bits) - ignored for Simple Text)
            ++sendingReference;
            sb.Append(GetBits(SendingReference, 8));

            // Area selection (8 bits) - unused
            sb.Append(GetBits(0x00, 8));

            // Validity period (8 bits) - unused
            sb.Append(GetBits(0x00, 8));

            // Forward Address (32 bits) - ignored for Simple Text
            sb.Append(GetBits(0x00, 32));

            // Flags (8 bits) 
            sb.Append(GetBits(isConfirmationReq ? 0x40 : 0x00, 8));
            
            // Length in bites (16 bits) + the encoding one
            sb.Append(GetBits((text.Length/2) * 8, 16));

            // Length in bytes (16 bits) + the encoding one
            sb.Append(GetBits(text.Length/2, 16));

            // Text message
            for (int i = 0; i < text.Length / 2; i++)
            {

                sb.Append(GetBits(Convert.ToInt16(text.Substring(i * 2, 2), 16), 8));
            }
            //sb.Append(text);

            /*
            // Transaction Id 
            sb.Append(GetBits(TransactionId, 32));

            // Gw Report
            sb.Append(GetBits(0x01, 8));
            */

            // get the header with the length
            String header = Header.GetHeaderBinary(sb.ToString().Length / 8);

            // add header in front of the request
            return BinaryStringToHexString($"{header}{sb.ToString()}", Padding.RIGHT);
        }

        public static byte[] GetBytes(Int64 sourceISSI, Int64 destinationISSI, String text, bool isConfirmationReq)
        {
            String res = GetInstance(sourceISSI, destinationISSI, text, isConfirmationReq);

            byte[] response = new byte[res.Length / 2];

            for (int i = 0; i < res.Length / 2; i++)
                response[i] = (byte)Convert.ToInt16(res.Substring(i * 2, 2), 16);

            return response;
        }
    }
}