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 FutureValue
{
	public partial class frmFutureValue : Form
	{
		public frmFutureValue()
		{
			InitializeComponent();
		}

		// DONE: Declare the rectangular array and the row index here
		string[,] calculations = new string[10, 4];
		int row = 0;

		private void btnCalculate_Click(object sender, EventArgs e)
		{
			try {
				if (IsValidData()) {
					decimal monthlyInvestment =
						Convert.ToDecimal(txtMonthlyInvestment.Text);
					decimal yearlyInterestRate =
						Convert.ToDecimal(txtInterestRate.Text);
					int years = Convert.ToInt32(txtYears.Text);

					int months = years * 12;
					decimal interestRateMonthly = yearlyInterestRate / 12 / 100;

					decimal futureValue = CalculateFutureValue(
						monthlyInvestment, interestRateMonthly, months);
					txtFutureValue.Text = futureValue.ToString("c");
					txtMonthlyInvestment.Focus();

					// DONE: Add the calculation to the rectangular array here
					calculations[row, 0] = monthlyInvestment.ToString("c");
					calculations[row, 1] = yearlyInterestRate.ToString("p");
					calculations[row, 2] = years.ToString();
					calculations[row, 3] = futureValue.ToString("c");
					row++;
				}
			}
			catch (Exception ex) {
				MessageBox.Show(ex.Message + "\n\n" +
					ex.GetType().ToString() + "\n" +
					ex.StackTrace, "Exception");
			}
		}

		public bool IsValidData()
		{
			bool success = true;
			string errorMessage = "";

			// Validate the Monthly Investment text box
			errorMessage += IsDecimal(txtMonthlyInvestment.Text, txtMonthlyInvestment.Tag.ToString());
			errorMessage += IsWithinRange(txtMonthlyInvestment.Text, txtMonthlyInvestment.Tag.ToString(), 1, 1000);

			// Validate the Yearly Interest Rate text box
			errorMessage += IsDecimal(txtInterestRate.Text, txtInterestRate.Tag.ToString());
			errorMessage += IsWithinRange(txtInterestRate.Text, txtInterestRate.Tag.ToString(), 1, 20);

			// Validate the Number of Years text box
			errorMessage += IsInt32(txtYears.Text, txtYears.Tag.ToString());
			errorMessage += IsWithinRange(txtYears.Text, txtYears.Tag.ToString(), 1, 40);

			if (errorMessage != "") {
				success = false;
				MessageBox.Show(errorMessage, "Entry Error");
			}
			return success;
		}

		public static string IsPresent(string value, string name)
		{
			string msg = "";
			if (value == "")
				msg += name + " is a required field.\n";
			return msg;
		}

		public static string IsDecimal(string value, string name)
		{
			string msg = "";
			if (!Decimal.TryParse(value, out _))
				msg += name + " must be a valid decimal value.\n";
			return msg;
		}

		public static string IsInt32(string value, string name)
		{
			string msg = "";
			if (!Int32.TryParse(value, out _))
				msg += name + " must be a valid integer value.\n";
			return msg;
		}

		public static string IsWithinRange(string value, string name, decimal min, decimal max)
		{
			string msg = "";
			if (Decimal.TryParse(value, out decimal number))
				if (number < min || number > max)
					msg += name + " must be between " + min + " and " + max + ".\n";
			return msg;
		}
		private decimal CalculateFutureValue(decimal monthlyInvestment,
			decimal monthlyInterestRate, int months)
		{
			decimal futureValue = 0m;
			for (int i = 0; i < months; i++)
				futureValue = (futureValue + monthlyInvestment)
					* (1 + monthlyInterestRate);
			return futureValue;
		}

		private void btnExit_Click(object sender, EventArgs e)
		{
			// DONE: Display the rectangular array in a dialog box here
			string msg = "Inv/Mo\tRate\tYears\tFuture Values\n";
			if (row > 0) {
				for (int i = 0; i < row; i++) {
					for (int j = 0; j < 4; j++)
						msg += calculations[i, j] + "\t";
					msg += "\n";
				}
				MessageBox.Show(msg, "Future Value Calculations");
			}
			this.Close();
		}

	}
}