laatzen/Common/Ui/GenesisToolBox/Ctls/LoginForm.cs

namespace Xylem.Common.Ui.GenesisToolBox.Ctls
{
    using System;
    using System.Security.Cryptography;
    using System.Text;
    using System.Windows.Forms;

    public partial class LoginForm : UserControl
    {
        private readonly Action<string, string, object> submittedCallback;

        public LoginForm()
        {
            this.InitializeComponent();

            this.Dock = DockStyle.Fill;
        }

        public LoginForm(Action<string, string, object> submittedCallback) : this()
            => this.submittedCallback = submittedCallback;

        private void LoginButtonClick(object sender, EventArgs e)
        {
            this.ErrorMessage.Text = default(string);
            this.LoginErrorProvider.Clear();

            var isValid = true;

            if (string.IsNullOrWhiteSpace(this.Username.Text))
            {
                isValid = false;

                this.LoginErrorProvider.SetError(this.Username, "Username is required.");
            }

            if (string.IsNullOrWhiteSpace(this.Password.Text))
            {
                isValid = false;

                this.LoginErrorProvider.SetError(this.Password, "Password is required.");
            }

            if (isValid)
            {
                this.submittedCallback?.Invoke(this.Username.Text, this.Password.Text.ComputeBase64Hash(), this);
            }
        }

        internal void ShowError(string errorMessage)
            => this.ErrorMessage.Text = errorMessage;
    }

    internal static class PasswordExtensions
    {
        internal static string ComputeBase64Hash(this string plainText)
        {
            if (string.IsNullOrWhiteSpace(plainText))
            {
                return plainText;
            }

            var buffer = Encoding.UTF8.GetBytes(plainText);
            var hash = SHA256.Create().ComputeHash(buffer);

            return Convert.ToBase64String(hash);
        }
    }
}