using System;
using System.Text;

namespace FitnesseTutorial
{
	/// <summary>
	/// Summary description for Calculator.
	/// </summary>
	public class Calculator
	{
		private StringBuilder displayLine;

		public Calculator() 
		{
			displayLine = new StringBuilder();
		}
		
		public void add()
		{
			displayLine.Append("+");
		}

		public void clear()
		{
			displayLine = new System.Text.StringBuilder();
		}

		public string display()
		{
			return displayLine.ToString();
		}

		public void sum()
		{
			String line = displayLine.ToString();
			String[] numbers = line.Split('+');
			int total = 0;
			foreach(String number in numbers)
			{
				int num = int.Parse(number);
				total += num;
			}
			displayLine = new StringBuilder();
			displayLine.Append(total.ToString());
		}

		public void one()
		{
			displayLine.Append("1");
		}

		public void two()
		{
			displayLine.Append("2");
		}

		public void three()
		{
			displayLine.Append("3");
		}

		public void four()
		{
			displayLine.Append("4");
		}

		public void five()
		{
			displayLine.Append("5");
		}

		public void six()
		{
			displayLine.Append("6");
		}

		public void seven()
		{
			displayLine.Append("7");
		}

		public void eight()
		{
			displayLine.Append("8");
		}

		public void nine()
		{
			displayLine.Append("9");
		}

		public void zero()
		{
			displayLine.Append("0");
		}
	}
}