using System;
using System.Text;
using System.Windows.Forms;

namespace DataStreamInterfaceTest
{
    public class ActivityLog
    {
        const int LinesCount = 50;

        TextBox textBox;
        string[] lines;
        string activity;

        public ActivityLog(TextBox textBox)
        {
            this.textBox = textBox;
            lines = new string[LinesCount];
            for (int i = 0; i < LinesCount; i++) lines[i] = string.Empty;
        }

        public void Print(string log)
        {
            for (int i = LinesCount - 1; i > 0; i--) lines[i] = lines[i - 1];
            lines[0] = log;
            DisplayLines();
        }

        private void DisplayLines()
        {
            StringBuilder sb = new StringBuilder();
            foreach (var line in lines) sb.AppendLine(line);
            textBox.Text = sb.ToString();
        }
    }
}