public Form1()
    {
        server = "localhost";
        database = "tut1";
        uid = "root";
        password = "";

        string connString;
        connString = $"SERVER={server};DATABASE={database};UID={uid};PASSWORD={password};";

        conn = new MySqlConnection(connString);

        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void btnRegister_Click(object sender, EventArgs e)
    {
        string user = tbUser.Text;
        string pass = tbPass.Text;

        if (Register(user, pass))
        {
            MessageBox.Show($"User {user} has been created!");
        }
        else
        {
            MessageBox.Show($"User {user} has not been created!");
        }
    }
    private void btnLogin_Click(object sender, EventArgs e)
    {
        string user = tbUser.Text;
        string pass = tbPass.Text;

        if (IsLogin(user, pass))
        {
            MessageBox.Show($"Welcome {user} !");
        }
        else
        {
            MessageBox.Show($"User {user} does not exists or password is incorrect!");
        }
    }

    public bool Register(string user, string pass)
    {
        string query = $"INSERT INTO users (id, username, password) VALUES ('', '{user}', '{pass}');";

        try
        {
            if (OpenConnection())
            {
                MySqlCommand cmd = new MySqlCommand(query, conn);
                try
                {
                    cmd.ExecuteNonQuery();
                    return true;
                }
                catch (Exception ex)
                {
                    return false;
                }
            }
            else
            {
                conn.Close();
                return false;
            }
        }
        catch (Exception ex)
        {
            conn.Close();
            return false;
        }
    }
    public bool IsLogin(string user, string pass)
    {
        string query = $"SELECT * FROM users WHERE username ='{user}' AND password = '{pass}';";

        try
        {
            if (OpenConnection())
            {
                MySqlCommand cmd = new MySqlCommand(query, conn);
                MySqlDataReader reader = cmd.ExecuteReader();

                if (reader.Read())
                {
                    reader.Close();
                    conn.Close();
                    return true;
                }
                else
                {
                    reader.Close();
                    conn.Close();
                    return false;
                }
            }
            else
            {
                conn.Close();
                return false;
            }
        } catch (Exception ex)
        {
            conn.Close();
            return false;
        }
    }
    private bool OpenConnection()
    {
        try
        {
            conn.Open();
            return true;
        }
        catch (MySqlException ex)
        {
            switch (ex.Number)
            {
            case 0:
                MessageBox.Show("Connection to the server failed!");
                break;
            case 1045:
                MessageBox.Show("Server username or password is incorrect");
                break;
            }
            return false;
        }
    }

}