using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

using System.IO;

namespace IBCNDecoder
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnOpenFile_Click(object sender, EventArgs e)
        {
            openFileDialog1.ShowDialog();

            using (BinaryReader ibcnReader = new BinaryReader(File.Open(openFileDialog1.FileName, FileMode.Open)))
            {
                tbFileName.Text = openFileDialog1.FileName.ToString();

                int length = (int)ibcnReader.BaseStream.Length;
                ibcnReader.BaseStream.Position = 0;

                ibcnReader.BaseStream.Position = 0;

                byte[] ibcnBytes = ibcnReader.ReadBytes(length);

                StringBuilder rawBytes = new StringBuilder(128);

                for (int i = 0; i < length; i++)
                {
                    rawBytes.Append(ibcnBytes[i].ToString("X"));
                    rawBytes.Append(" ");
                }
                rtbRawMessage.Text = rawBytes.ToString();

                double byte1Mult = Math.Pow(2, 24);
                double byte2Mult = Math.Pow(2, 16);
                double byte3Mult = Math.Pow(2, 8);

                double latitude = (1e-6 * ((ibcnBytes[8] * byte1Mult) + (ibcnBytes[9] * byte2Mult) + (ibcnBytes[10] * byte3Mult) + ibcnBytes[11])) - 90.0;
                tbLatitude.Text = latitude.ToString();

                double longitude = (1e-6 * ((ibcnBytes[12] * byte1Mult) + (ibcnBytes[13] * byte2Mult) + (ibcnBytes[14] * byte3Mult) + ibcnBytes[15])) - 180.0;
                tbLongitude.Text = longitude.ToString();

                double gpsTime = (ibcnBytes[3] * byte1Mult) + (ibcnBytes[4] * byte2Mult) + (ibcnBytes[5] * byte3Mult) + ibcnBytes[6];
                DateTime gpsReferenceTime = new DateTime(1980, 1, 6);
                DateTime gpsDateTime = gpsReferenceTime.AddSeconds(gpsTime);

                //Here's another way to convert taking care of the endian difference
                //byte[] tempBytes = new byte[4];
                //Array.Copy(ibcnBytes, 3, tempBytes, 0, 4);
                //Array.Reverse(tempBytes);
                //int temp = BitConverter.ToInt32(tempBytes, 0);

                double hdop = 0.5 * (ibcnBytes[7] & 0X07);
                tbHDOP.Text = hdop.ToString();

                double numSats = 3 + ((ibcnBytes[7] >> 3) & 0X07);
                tbNumSats.Text = numSats.ToString();

                this.Refresh();
                Application.DoEvents();
            }
        }
    }
}