Aplikasi billing warnet

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Diagnostics;

namespace Billing_apliaksi

{

    public partial class Form1 : Form

    {

        private Stopwatch wkt = null;

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            if (textBox1.Text != "")

            {

                wkt = new Stopwatch();

                if (button1.Text == "Log In")

                {

                    label2.Visible = true;

                    wkt.Start();

                    button1.Text = "Stop";

                }

                else if (button1.Text == "Stop")

                {

                    wkt.Stop();

                    if (wkt.Elapsed.TotalMinutes <= 30.00)

                    {

                        MessageBox.Show("Jumlah tagihan anda sebesar Rp.1000", "Total Tagihan");

                    }

                    else if (wkt.Elapsed.TotalHours <= 1.00)

                    {

                        MessageBox.Show("Jumlah Tagihan anda sebesar Rp.2000", "Total");

                    }

                    wkt.Reset();

                    label2.Visible = false;

                    button1.Text = "Log In";

                    textBox1.Text = null;

                }

                

            }

            else if (textBox1.Text =="")

            {

                MessageBox.Show("Nama Harus diisi! ", "Important Message");

            }        

         }

        private void timer1_Tick(object sender, EventArgs e)

        {

            if (wkt != null)

            {

                label2.Text = wkt.Elapsed.ToString(@"hh\:mm\:ss");

            }

        }

    }

}