using System;

public static class Program

{

    private static string apiServiceBaseUrl = "https://blah.com.au/auth/admin/realms/umd-dev/";

    private static string apiServiceBaseUrlNoRealm = "https://blah.com.au/auth/admin/realms/";

    public static void Main()

    {

        Console.WriteLine("Original with null realm:");

        Console.WriteLine(apiServiceBaseUrl.AppendUrlPath());

​

        Console.WriteLine("New with null realm:");

        Console.WriteLine(apiServiceBaseUrl.AppendUrlPathNew());

​

        Console.WriteLine("Original with realm:");

        Console.WriteLine(apiServiceBaseUrlNoRealm.AppendUrlPath("umd-test"));

​

        Console.WriteLine("New with realm:");

        Console.WriteLine(apiServiceBaseUrlNoRealm.AppendUrlPathNew("umd-test"));

    }

}

​

public static class StringExtensions {

public static string AppendUrlPathNew(this string basePath, string suffix = null)

{

    var baseUri = new Uri(basePath);

​

    if (suffix != null && Uri.TryCreate(baseUri, suffix, out Uri result)) {

        return result.ToString();

    }

    else

    {

        return baseUri.ToString();

    }

}

​

public static string AppendUrlPath(this string basePath, string suffix = null)

{

    return AppendPath(basePath, suffix, '/');

}

​

public static string AppendPath(this string basePath, string suffix, char pathSeparator = '/')

{

    // If the base path is null or empty, the result is a path with a single leading slash.

    // If the suffix is null or empty, the result is a path with a single trailing slash.

    return $"{(basePath ?? "").Trim().TrimEnd(pathSeparator)}{pathSeparator}{(suffix ?? "").Trim().TrimStart(pathSeparator)}";

}   

}