using System;

using System.Text.RegularExpressions;

​

using System.IO;

public class Program

{

    public static void Main()

    {

        //var txt = "Nitish.txt";

        var d3plot = "Nitish.d3plot.msh.1245";

        Console.WriteLine(HandleSpecialFileExtensions(d3plot));

        /*var d3ploat007 = "Nitish.d3plot007";

        var asm = "Nitish.asm.1";

        var prt = "Nitish.prt.12";

        Console.WriteLine(HandleSpecialFileExtensions(txt));

        Console.WriteLine(HandleSpecialFileExtensions(d3plot));

        Console.WriteLine(HandleSpecialFileExtensions(d3ploat007));

        Console.WriteLine(HandleSpecialFileExtensions(asm));

        Console.WriteLine(HandleSpecialFileExtensions(prt));

        */

    }

    public static string HandleSpecialFileExtensions(string filePath) 

    {

        Console.WriteLine(filePath);

        var fileExt = Path.GetExtension(filePath).ToLowerInvariant(); //Extract extension txt Last string from .

        Console.WriteLine(fileExt);  //123456

        var fileName = Path.GetFileName(filePath); //Nitish.txt

        Console.WriteLine(fileName);

​

        // Need to treat these two extensions as Fluent Case Files

        if ((fileName.ToLowerInvariant().EndsWith(".cas.gz") == true) ||

            (fileName.ToLowerInvariant().EndsWith(".cas.h5") == true))

        {

            fileExt = ".cas";

            Console.WriteLine("Inside cas");

        }

        // Need to treat these two extensions as Fluent Case Files

        else if ((fileName.ToLowerInvariant().EndsWith(".msh.gz") == true) ||

                 (fileName.ToLowerInvariant().EndsWith(".msh.h5") == true))

        {

            fileExt = ".msh";

            Console.WriteLine("Inside msh");

        }

        // Need to treat these two extensions as Fluent Data Files

        else if (fileName.ToLowerInvariant().EndsWith(".dat.gz") == true)

        {

            fileExt = ".dat.gz";

            Console.WriteLine("Inside dat");

        }

        else if (fileName.ToLowerInvariant().EndsWith(".dat.h5") == true)

        {

            fileExt = ".dat.h5";

            Console.WriteLine("Inside dat.h5");

        }

        else if (Regex.IsMatch(fileName.ToLowerInvariant(), "\\.prt\\..*"))

        {

            fileExt = ".prt";

        }

        else if (Regex.IsMatch(fileName.ToLowerInvariant(), "\\.asm\\..*"))

        {

            fileExt = ".asm";

        }

        else if (Regex.IsMatch(fileName.ToLowerInvariant(), "\\.d3plot.*"))

        {

            fileExt = ".d3plot";

            Console.WriteLine("Inside d3plot");

        }           

​

        return fileExt;

    }

}