using System;

public class SerialGenerator{

    public string req(string strPrefix){

        Console.WriteLine("req:"+strPrefix);

        string curSer = this.lastSerial(strPrefix);

        Console.WriteLine("current Serial:"+curSer);

        int seqCurrent = this.getSeq(curSer);

        string reFmtSerial = this.reformatSerial(strPrefix, string.Format("{0}",seqCurrent + 1));        

        Console.WriteLine("reFmtSerial:"+reFmtSerial);

        return reFmtSerial;

    }

    //Get the int, know the format will be (INT-STRING)

    private int getSeq(string currentSerial){

        string[] cSerial = currentSerial.Split('-');

        return Convert.ToInt32(cSerial[0]);

    }

    private string lastSerial(string segment){

        string strSerial ="";

        //Call API 

        strSerial = myApiCall(segment);

        return strSerial;

    }

    private string reformatSerial(string strPrefix,string strInput){

        string strFmtSerial=string.Format(strPrefix,strInput);

        return strFmtSerial;

    }

    private string myApiCall(string param){

        Random rnd = new Random();

        int iRandom  = rnd.Next(1, 13);

        return string.Format("{0}-SN",iRandom);

    }

}

​

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        SerialGenerator serialGen = new SerialGenerator();

        string fmtPattern = "{0}-SN";

        string ret = serialGen.req(fmtPattern);

        Console.WriteLine(string.Format("Serial: {0}",ret));

    }

}