using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp7
{
    public partial class Form1 : Form
    {
        public static int TooLargeCounter = 0;
        public static Boolean replace = false;
        public static Boolean resetExpression = false;

        public static Nullable<Int64> leftOp = null;
        public static Int64 rightOp;
        public static Nullable<char> operation = null;

        public Form1()
        {
            InitializeComponent();

            DivideOp_Button.Text = "\u00F7";
        }

        public Int64 ConvertOutputToLong()
        {
            while (OutputText.Text.Contains(','))
            {
                OutputText.Text = OutputText.Text.Remove(OutputText.Text.IndexOf(','), 1);
            }

            return Convert.ToInt64(OutputText.Text);
        }

        public void NumericKey_Click(object sender, EventArgs args)
        {
            Button alpha = sender as Button;

            if (alpha == null) // The typecast failed
                return;        // This... probably shouldn't ever happen anyway

            if (OutputText.Text.Length > 14)
            {
                TooLargeCounter++;

                if (TooLargeCounter % 3 == 0)
                {
                    MessageBox.Show("Sorry, this value is too large to be stored in memory.");
                }

                return;
            }

            if (replace)
            {
                OutputText.Text = "";
                replace = false;
            }

            if (OutputText.Text.CompareTo("0") == 0)
            {
                OutputText.Text = "";
            }

            if (resetExpression)
            {
                OutputText.Text = "";
                CurrentExpression.Text = "";
                leftOp = null;
                resetExpression = false;
            }

            OutputText.AppendText(alpha.Text);

            if (OutputText.Text.Length > 3) // n,nnn and beyond
            {
                Int64 slacker = ConvertOutputToLong();
                OutputText.Text = String.Format("{0:#,0}", slacker);
            }
        }

        public void ArithmeticButton_Click(object sender, EventArgs args)
        {
            Button alpha = sender as Button;

            if (alpha == null) // The typecast failed
                return;        // This... probably shouldn't ever happen anyway

            //CurrentExpression.AppendText(alpha.Text + " " + OutputText.Text);
            if (!leftOp.HasValue)
            {
                leftOp = ConvertOutputToLong();
                operation = alpha.Text[0];
                replace = true;
            }
            else
            { 
                rightOp = ConvertOutputToLong();

                switch (operation)
                {
                    case ('+'):
                        leftOp += rightOp;
                        replace = true;
                        break;
                    case ('-'):
                        leftOp -= rightOp;
                        replace = true;
                        break;
                    case ('*'):
                        leftOp *= rightOp;
                        replace = true;
                        break;
                    case ('\u00F7'):
                        leftOp /= rightOp;
                        replace = true;
                        break;
                    case ('='):
                        CurrentExpression.Text = "";
                        resetExpression = false;
                        break;
                    default:
                        break;
                }
                if (alpha.Text[0] == '=')
                {
                    resetExpression = true;
                    operation = alpha.Text[0];
                }
                else
                {
                    operation = alpha.Text[0];
                }
            }

            CurrentExpression.Text = " " + alpha.Text + " " + OutputText.Text + " " + CurrentExpression.Text;
            OutputText.Text = String.Format("{0:#,0}", leftOp);
        }

        private void Clear_Button_Click(object sender, EventArgs e)
        {
            CurrentExpression.Text = "";
            leftOp = null;
        }

        private void ClearExpression_Button_Click(object sender, EventArgs e)
        {
            OutputText.Text = "0";
        }

        private void Negate_Button_Click(object sender, EventArgs e)
        {
            /*  An exercise for you to complete, if you like 
            if (OutputText.Text[OutputText.Text.Length - 1] != '-')
                OutputText.Text = OutputText.Text.Insert(OutputText.Text.Length - 1, "-");
            else
                OutputText.Text = OutputText.Text.Remove(OutputText.Text.Length - 1, 1);
            */
        }
    }
}