Form 5 - Настроойки

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Data.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace laba8
{
    public partial class Form5 : Form
    {
        Table<User> users;
        Table<Priv> privs;
        Table<UserPriv> userPrivs;
        DataContext context;
        User user;
        public Form5()
        {
            InitializeComponent();

                context = appcontext.GetDataContext();
                users = context.GetTable<User>();
                privs = context.GetTable<Priv>();
                userPrivs = context.GetTable<UserPriv>();

                ListBox1Update();

                for (int i = 0; i < privs.Count(); i++)
                {
                    listBox3.Items.Add(privs.Skip(i).First().Name);
                }


        }
        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            var index = listBox1.SelectedIndex;
            if (index >= 0)
            {
                user = users.Skip(index).First();
                var curUserPrivs = userPrivs.Where(v => v.UserID == user.UserID);
                listBox2.Items.Clear();
                for (int i = 0; i < curUserPrivs.Count(); i++)
                {
                    listBox2.Items.Add(privs.First(v => v.PrivID == curUserPrivs.Skip(i).First().PrivID).Name);
                }
                textBox1.Text = user.UserName.Trim(' ');
                textBox2.Text = user.Password.Trim(' ');
                textBox3.Text = user.FullName.Trim(' ');
                panel1.Visible = true;
            }
        }
        private void button1_Click(object sender, EventArgs e)
        {
            var index = listBox1.SelectedIndex;
            var user = new User { FullName = "New", UserName = "User", Password = "1", UserID = users.Select(v => v.UserID).Max() + 1 };
            users.InsertOnSubmit(user);
            context.SubmitChanges();
            ListBox1Update();
            listBox1.SelectedIndex = index;


        }

        private void button2_Click(object sender, EventArgs e)
        {

        }

        private void button3_Click(object sender, EventArgs e)
        {

        }

        private void button4_Click(object sender, EventArgs e)
        {
            var index = listBox1.SelectedIndex;
            var user = new User { FullName = "Новый пользователь", UserName = "User", Password = "1", UserID = users.Select(v => v.UserID).Max() + 1 };
            users.InsertOnSubmit(user);
            context.SubmitChanges();
            ListBox1Update();
            listBox1.SelectedIndex = index;
        }

        private void ListBox1Update()
        {
            listBox1.Items.Clear();
            for (int i = 0; i < users.Count(); i++)
            {
                listBox1.Items.Add(users.Skip(i).First().FullName);
            }
        }

        private void listBox1_SelectedIndexChanged_1(object sender, EventArgs e)
        {
            var index = listBox1.SelectedIndex;
            if (index >= 0)
            {
                user = users.Skip(index).First();
                var curUserPrivs = userPrivs.Where(v => v.UserID == user.UserID);
                listBox2.Items.Clear();
                for (int i = 0; i < curUserPrivs.Count(); i++)
                {
                    listBox2.Items.Add(privs.First(v => v.PrivID == curUserPrivs.Skip(i).First().PrivID).Name);
                }
                textBox1.Text = user.UserName.Trim(' ');
                textBox2.Text = user.Password.Trim(' ');
                textBox3.Text = user.FullName.Trim(' ');
                panel1.Visible = true;
            }
        }

        private void button5_Click(object sender, EventArgs e)
        {
            var index = listBox1.SelectedIndex;
            user.UserName = textBox1.Text;
            user.Password = textBox2.Text;
            user.FullName = textBox3.Text;
            context.SubmitChanges();
            ListBox1Update();
            listBox1.SelectedIndex = index;
        }

        private void button3_Click_1(object sender, EventArgs e)
        {
            var index = listBox3.SelectedIndex;
            if (index >= 0)
            {
                var priv = privs.Skip(index).First();

                if (userPrivs.FirstOrDefault(v => v.PrivID == priv.PrivID && v.UserID == user.UserID) == null)
                {
                    var userPriv = new UserPriv { PrivID = priv.PrivID, UserID = user.UserID, Id = userPrivs.Select(v => v.Id).Max() + 1 };
                    userPrivs.InsertOnSubmit(userPriv);
                    listBox2.Items.Add(priv.Name);
                    context.SubmitChanges();
                }
            }
        }

        private void button2_Click_1(object sender, EventArgs e)
        {
            var index = listBox1.SelectedIndex;
            if (index >= 0)
            {
                var user = users.Skip(index).First();
                if (user.UserID != Program.user.UserID)
                {
                    var prvs = userPrivs.Where(v => v.UserID == user.UserID).ToList();
                    userPrivs.DeleteAllOnSubmit(prvs);
                    users.DeleteOnSubmit(user);
                    context.SubmitChanges();

                    ListBox1Update();
                    panel1.Visible = false;
                }
                else
                {
                    MessageBox.Show("Невозможно удалить себя!");
                }
            }
        }

        private void button4_Click_1(object sender, EventArgs e)
        {
            var index = listBox2.SelectedIndex;
            if (index >= 0)
            {
                if (user.UserID != Program.user.UserID)
                {
                    var userPriv = userPrivs.Where(v => v.UserID == user.UserID).Skip(index).First();
                    userPrivs.DeleteOnSubmit(userPriv);
                    context.SubmitChanges();
                    listBox2.Items.RemoveAt(index);
                }
                else
                {
                    MessageBox.Show("Невозможно лишить себя прав!");
                }
            }
        }
    }
}