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 TextBoxTest
{
    public partial class Form1 : Form
    {
        public Form1()
        {

            InitializeComponent();
            this.btnOK.Enabled = true;
            // Tag values for testing if the data is valid
            this.txtAddress.Tag = false;
            this.txtAge.Tag = false;
            this.txtName.Tag = false;
            this.txtOccupation.Tag = false;
            // Subscriptions to events
            this.txtName.Validating += new
             System.ComponentModel.CancelEventHandler(this.txtBoxEmpty_Validating);
            this.txtAddress.Validating += new
             System.ComponentModel.CancelEventHandler(this.txtBoxEmpty_Validating);
            this.txtOccupation.Validating += new
 System.ComponentModel.CancelEventHandler(this.txtOccupation_Validating);
            this.txtAge.KeyPress += new
 System.Windows.Forms.KeyPressEventHandler(this.txtAge_KeyPress);
            this.txtAge.Validating += new
 System.ComponentModel.CancelEventHandler(this.txtBoxEmpty_Validating);
            this.txtName.TextChanged += new System.EventHandler(this.txtBox_TextChanged);
            this.txtAddress.TextChanged += new
             System.EventHandler(this.txtBox_TextChanged);
            this.txtAge.TextChanged += new System.EventHandler(this.txtBox_TextChanged);
            this.txtOccupation.TextChanged += new
             System.EventHandler(this.txtBox_TextChanged);

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void label1_Click(object sender, EventArgs e)
        {

        }

        private void textBox5_TextChanged(object sender, EventArgs e)
        {

        }




        private void btnOK_Click(object sender, System.EventArgs e)
        {
            // No testing for invalid values are made, as that should
            // not be necessary
            string output;
            // Concatenate the text values of the four TextBoxes
            output = "Name: " + this.txtName.Text + "\r\n";
            output += "Address: " + this.txtAddress.Text + "\r\n";
            output += "Occupation: " + this.txtOccupation.Text + "\r\n";
            output += "Age: " + this.txtAge.Text;
            // Insert the new text
            this.txtOutput.Text = output;
        }


        private void textBox3_TextChanged(object sender, EventArgs e)
        {

        }

        private void btnHelp_Click(object sender, System.EventArgs e)
        {
            // Write a short description of each TextBox in the Output TextBox
            string output;
            output = "Name = Your name\r\n";
            output += "Address = Your address\r\n";
            output += "Occupation = Only allowed value is 'Programmer'\r\n";
            output += "Age = Your age";
            // Insert the new text
            this.txtOutput.Text = output;
        }

        private void txtOccupation_Validating(object sender, System.ComponentModel.CancelEventArgs e)
        {
            // Cast the sender object to a textbox
            TextBox tb = (TextBox)sender;
            // Check if the values are correct
            if (tb.Text.CompareTo("Programmer") == 0 || tb.Text.Length == 0)
            {
                tb.Tag = true;
                tb.BackColor = System.Drawing.SystemColors.Window;
            }
            else
            {
                tb.Tag = false;
                tb.BackColor = Color.Red;
            }
            // Set the state of the OK button
            ValidateAll();
        }

        private void txtBoxEmpty_Validating(object sender, System.ComponentModel.CancelEventArgs e)
        {
            // We know the sender is a TextBox, so we cast the sender object to that
            TextBox tb = (TextBox)sender;
            // If the text is empty we set the background color of the
            // Textbox to red to indicate a problem. We use the tag value
            // of the control to indicate if the control contains valid
            // information.
            if (tb.Text.Length == 0)
            {
                tb.BackColor = Color.Red;
                tb.Tag = false;

                // In this case we do not want to cancel further processing,
                // but if we had wanted to do this, we would have added this line:
                // e.Cancel = true;
            }
            else
            {
                tb.BackColor = System.Drawing.SystemColors.Window;
                tb.Tag = true;
            }
            // Finally, we call ValidateAll which will set the value of
            // the OK button.
            ValidateAll();
        }

        private void txtAge_KeyPress(object sender,
 System.Windows.Forms.KeyPressEventArgs e)
        {
            if ((e.KeyChar < 48 || e.KeyChar > 57) && e.KeyChar != 8)
                e.Handled = true; // Remove the character
        }

        private void txtBox_TextChanged(object sender, System.EventArgs e)
        {
            // Cast the sender object to a Textbox
            TextBox tb = (TextBox)sender;
            // Test if the data is valid and set the tag and background
            // color accordingly.
            if (tb.Text.Length == 0 && tb != txtOccupation)
            {
                tb.Tag = false;
                tb.BackColor = Color.Red;
            }
            else if (tb == txtOccupation &&
            (tb.Text.Length != 0 && tb.Text.CompareTo("Programmer") != 0))
            {
                // Don't set the color here, as it will color change while the user
                // is typing
                tb.Tag = false;
            }
            else
            {
                tb.Tag = true;
                tb.BackColor = SystemColors.Window;
            }
            // Call ValidateAll to set the OK button
            ValidateAll();
        }

        private void ValidateAll()
        {
            // Set the OK button to enabled if all the Tags are true
            this.btnOK.Enabled = ((bool)(this.txtAddress.Tag) &&
            (bool)(this.txtAge.Tag) &&
            (bool)(this.txtName.Tag) &&
            (bool)(this.txtOccupation.Tag));
        }



    }
}