Diplom_B/LoginForm.cs

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;
using Diplom_B.DB;

namespace Diplom_B
{
	public partial class LoginForm : Form
	{
		public LoginForm()
		{
			InitializeComponent();
			Init();
		}

		public void Init()
    {
			nameBox.Items.AddRange(WorkDB.GetUserList());
    }

		private Task errDrop;
		private void ShowError(string msg = null)
		{
			errorLabel.Text = string.IsNullOrEmpty(msg) ? "Неизвестная ошибка." : msg;
			errorLabel.Visible = true;
			errDrop = new Task(() =>
			{
				var fd = errDrop.Id;
				Task.Delay(5000).Wait();
				if (errDrop.Id == fd)
					if (InvokeRequired) Invoke((Action)(() => { errorLabel.Visible = false; }));
					else errorLabel.Visible = false;
			});
			errDrop.Start();
		}

		private void loginButton_Click(object sender, EventArgs e)
		{
			errorLabel.Text = "";
			var usr = new User(nameBox.Text, passBox.Text);
			if (!usr.CheckUser())
			{
				ShowError("Пользователя нет");
				return;
			}
			if (!usr.Login())
			{
				ShowError("Неверный пароль");
				return;
			}

			Program.user = usr;
			object form = null;
			switch(usr.Usr.Default)
      {
				case 0: form = new DogForm(); break;
				case 1: form = new DocForm(); break;
				case 2: form = new IzvForm(); break;
				case 3: form = new PostForm(); break;
				case 4: form = new IzdForm(); break;
				case 5: form = new ZakForm(); break;
				case 6: form = new SetForm(); break;
			}
			if (form == null) this.Close();

			this.Hide();
			((Form)form).Closed += (s, args) => this.Close();
			((Form)form).Show();
		}

    private void keyDown(object sender, KeyEventArgs e)
    {
			if (e.KeyCode == Keys.Enter)
				loginButton_Click(this, new EventArgs());
		}
  }
}