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 Payment
{
	public partial class frmCustomer : Form
	{
		public frmCustomer()
		{
			InitializeComponent();
		}

		bool isDataSaved = true;

		private void frmCustomer_Load(object sender, EventArgs e)
		{
			cboNames.Items.Add("Mike Smith");
			cboNames.Items.Add("Nancy Jones");
		}

		private void frmCustomer_FormClosing(object sender, FormClosingEventArgs e)
		{
			if (isDataSaved == false) {
				string msg = "This form contains unsaved data"
					+ "\n\nDo you want to save it?";

				DialogResult button =
					MessageBox.Show(msg, "Customer",
					MessageBoxButtons.YesNoCancel,
					MessageBoxIcon.Warning);

				if (button == DialogResult.Yes)
					if (IsValidData())
						this.SaveData();
					else
						e.Cancel = true;
				if (button == DialogResult.Cancel)
					e.Cancel = true;
			}
		}

		private void btnSelectPayment_Click(object sender, EventArgs e)
		{
			Form payment = new frmPayment();
			DialogResult selectedButton = payment.ShowDialog();
			if (selectedButton == DialogResult.OK)
				lblPayment.Text = (string)payment.Tag;
		}

		private void btnSave_Click(object sender, EventArgs e)
		{
			if (IsValidData())
				SaveData();
		}

		private void btnExit_Click(object sender, EventArgs e)
		{
			this.Close();
		}

		private void lblPayment_TextChanged(object sender, EventArgs e)
		{
			isDataSaved = false;
		}

		private void cboNames_SelectedIndexChanged(object sender, EventArgs e)
		{
			isDataSaved = false;
			lblPayment.Text = "";
		}

		private void SaveData()
		{
			cboNames.SelectedIndex = -1;
			lblPayment.Text = "";
			isDataSaved = true;
			cboNames.Focus();
		}

		private bool IsValidData()
		{
			if (cboNames.SelectedIndex == -1) {
				MessageBox.Show("You must select a customer",
					"Entry Error");
				return false;
			}
			if (lblPayment.Text == "") {
				MessageBox.Show("You must enter a payment",
					"Entry Error");
				return false;
			}
			return true;
		}
	}
}