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

namespace LibrarySDR.Requests
{
    public class SimpleTextSDSRequest
    {

        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 Int16 textEncoding;
        public Int16 TextEncoding { get { return textEncoding; } }

        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 Int32 EncodingType = 26;


        public SimpleTextSDSRequest(string hexSimpleTextSDSReceived)
        {
            String resp = hexSimpleTextSDSReceived;
            int i = 0;
            int prevIdx = 0;
            
            // get source SSI (32 bits = 4 byte = 8 hex characters)
            String hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 4*2));
            Int64.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out sourceISSI);

            // get destination SSI (32 bits = 4 byte = 8 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 4*2));
            Int64.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out destinationISSI);

            // get protocol identifier (8 bits = 1 byte = 2 hex characters)
            Int16 pi = 0;
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 2));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out pi);
            this.pi = (ProtocolIdentifier)pi;

            // get message reference (8 bits = 1 byte = 2 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 2));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out messageReference);

            // return if no more data to parse
            if (resp.Length < i + 1 * 2)
                return; 

            // get area selection (8 bits = 1 byte = 2 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 2));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out areaSelection);

            // return if no more data to parse
            if (resp.Length < i + 1 * 2)
                return;

            // get validity period (8 bits = 1 byte = 2 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 2));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out validityPeriod);

            // return if no more data to parse
            if (resp.Length < i + 4 * 2)
                return;

            // get forward address (32 bits = 4 byte = 8 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 4 * 2));
            Int64.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out forwardAddress);

            // get flags (8 bits = 1 byte = 2 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 2));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out flags);

            // parse the data flag
            dataFlag = new DataFlag(flags);

            // get length bits (16 bits = 2 byte = 4 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 4));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out lengthBits);

            // get length bytes (16 bits = 2 byte = 4 hex characters)
            hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 4));
            Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out lengthBytes);

            if (ProtocolIdentifier != ProtocolIdentifier.GPS && ProtocolIdentifier != ProtocolIdentifier.GPSUsingSDSTL
                && ProtocolIdentifier != ProtocolIdentifier.SimpleGPSWithoutSDSTL)
            {
                // get encoding (8 bits = 1 byte = 2 hex characters)
                hex = LittleToBigEndianHexString(resp.Substring(i = i + prevIdx, prevIdx = 2));
                Int16.TryParse(hex, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out textEncoding);
            }

            hexMessage = resp.Substring(i = i + prevIdx); // LittleToBigEndianHexString(resp.Substring(i = i + prevIdx));


            // arrabic unicode
            if (textEncoding == 26)
            {
                // convert the message to big endian
                //hexMessage = LittleToBigEndianHexString(hexMessage);

                // get the unicode for the hex message
                String message2 = "";
                int j = 0;
                while(j < hexMessage.Length)
                {
                    String hexChar = hexMessage.Substring(j, 4);
                    Int64 hexCharVal = Int64.Parse(hexChar, NumberStyles.HexNumber);
                    //Encoding.Unicode.GetString(hexCharVal);

                    message2 += HexToUnicode(hexChar);


                    j = j + 4;
                }

                message = Encoding.Unicode.GetString(StringToByteArray(hexMessage)); // For UTF-16

                message = message2;
            }
            else
            {
                for (int w = 0; w < hexMessage.Length / 2; w++)
                    message += (char)Convert.ToInt16(hexMessage.Substring(w * 2, 2), 16);
            }
            
        }


        public static char HexToUnicode(string hex)
        {
            byte[] bytes = HexToBytes(hex);
            char c;
            if (bytes.Length == 1)
            {
                c = (char)bytes[0];
            }
            else if (bytes.Length == 2)
            {
                c = (char)((bytes[0] << 8) + bytes[1]);
            }
            else
            {
                throw new Exception(hex);
            }

            return c;
        }

        public static byte[] HexToBytes(string hex)
        {
            hex = hex.Trim();

            byte[] bytes = new byte[hex.Length / 2];

            for (int index = 0; index < bytes.Length; index++)
            {
                bytes[index] = byte.Parse(hex.Substring(index * 2, 2), NumberStyles.HexNumber);
            }

            return bytes;
        }




        public static String GetInstance(Int64 sourceISSI, Int64 destinationISSI, String text)
        {
            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)
            sb.Append(GetBits((int)protocolIdentifier, 8));

            // Message reference (8 bits) - ignored for Simple Text)
            sb.Append(GetBits(0x00, 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) - ignored for Simple Text
            sb.Append(GetBits(0x00, 8));
            
            // Length in bites (16 bits) + the encoding one
            sb.Append(GetBits((text.Length + 1) * 8, 16));

            // Length in bytes (16 bits) + the encoding one
            sb.Append(GetBits(text.Length + 1, 16));

            // Encoding (8 bits) - Latin-1
            sb.Append(GetBits(EncodingType, 8)); 

            // Text message
            sb.Append(GetBits(text, Encoding.Unicode));

            // 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)
        {
            String res = GetInstance(sourceISSI, destinationISSI, text);

            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;
        }
    }
}