using System;

using HtmlAgilityPack;

using System.Xml;

using System.Text;

public class Program

{

    public const int gsmMaxLength = 160;

    public const int unicodeMaxLength = 70;

    public static void Main()       

    {

        string[] messages = new string[]

        {

            "ã111111111£222222222£333333333£444444444£555555555£666666666£777777777"

        };

        foreach(var msg in messages)

        {

            Console.WriteLine("{0} validated as: {1}", msg, Validate(msg));

        }

    }

    private static bool Validate(string message)

    {

        var textLength = message.Length;

        var utf8bytes = Encoding.UTF8.GetBytes(message);

        Encoding gsmEnc = new Mediaburst.Text.GSMEncoding();

        Encoding utf8Enc = new System.Text.UTF8Encoding();

        byte[] gsmBytes = gsmEnc.GetBytes(message);

        Console.WriteLine("message: {0}, textLength: {1}, utf8bytes.Length: {2}, gsmBytes.Length: {3}", message, textLength, utf8bytes.Length, gsmBytes.Length);

        foreach(var b in gsmBytes)

            Console.Write(String.Format("{0,10:X}", b));

        byte[] utf8Bytes = Encoding.Convert(gsmEnc, utf8Enc, gsmBytes);

        string backToString = utf8Enc.GetString(utf8Bytes);

        Console.WriteLine();

        Console.WriteLine("GSM-7 converted back to normal string: {0}", backToString);

        if (textLength > gsmMaxLength)

        {

            Feedback("Characters limit exceeded. Please rewrite message.");

            return false;

        }

        if (utf8bytes.Length <= gsmBytes.Length)

        {

            return true;

        }

        Console.WriteLine("Unicode detected.");

        if (unicodeMaxLength >= utf8bytes.Length)

        {

            return true;

        }

        else

        {

            Feedback("Unicode message limit is 70 characters. Please rewrite message.");

            return false;

        }

    }

    private static void Feedback(string msg)

    {

        Console.WriteLine(msg);

    }

}