class Program
    {
        static void Main(string[] args)
        {
            string rawin = @"C:\Users\**REDACTED**\Desktop\TrendIn.csv";
            string path = @"C:\Users\**REDACTED**\Desktop\ConvertedTrendData.csv";

            // Create output file "TrendIn.csv"
            //Input must be TimeStamp, Temp <UInt>
            using (StreamWriter sw = new StreamWriter(path, true))
            {
                // Open input file "ConvertedTrendData.csv"
                //Output will be Timestamp, DateTime, Temp <single>
                using (StreamReader sr = new StreamReader(rawin))
                {
                    while (sr.Peek() >= 0)
                    {
                        string s = sr.ReadLine();

                        string[] flds = s.Split(',');
                        flds[1] = EpochToDateTime(flds[0]).ToString();
                        flds[2] = UIntBinarytoFloat(flds[2]).ToString();
                        s = string.Join(",", flds);

                        sw.WriteLine(s);
                    }
                }
            }
        }

        // Unix Timestamp to DateTime
        private static DateTime EpochToDateTime(string strValue)
        {
            long.TryParse(strValue, out long timestamp);
            return EpochToDateTime(timestamp);
        }
        private static DateTime EpochToDateTime(long timestamp)
        {
            var epoch = new DateTime(1970, 1, 1, 0, 0, 0);

            string ts = timestamp.ToString();

            if (ts.Length <= 11)
            {
                return epoch.AddSeconds(timestamp);
            }
            else if (ts.Length > 11 && ts.Length <= 14)
            {  //Assuming  Milliseconds
                return epoch.AddMilliseconds(timestamp);
            }
            else

            {  //Assuming Microseconds - reduce by 1000s down to Milliseconds
                while (ts.Length > 14)
                {
                    ts = ts.Substring(0, ts.Length - 3);
                }
                timestamp = long.Parse(ts);
                return epoch.AddMilliseconds(timestamp);
            }
        }

        //Convert Unsigned Integer Binary Format to Float (single)
        private static Single UIntBinarytoFloat(string strValue)
        {
            uint.TryParse(strValue, out uint uintValue);
            return UIntBinarytoFloat(uintValue);
        }
        private static Single UIntBinarytoFloat(uint value)
        {
            byte[] bytes = BitConverter.GetBytes(value);
            return BitConverter.ToSingle(bytes, 0);
        }
    }
}