using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.Configuration;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
namespace Lab5
{
    public partial class Login : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if(!IsPostBack)
            {
                HeaderHypLink.Visible = false;
                lblStatus.Text = "";
                lblStatus.Visible = false;
                lblCookie.Visible = false;
                lblCustomerid.Visible = false;
                lblFirstname.Visible = false;
                lblLastname.Visible = false;
                lblStatus.Visible = false;

                HttpCookie cookie = Request.Cookies["Login"];
                if (cookie != null)
                {
                    username.Text = Decode(cookie["UserName"]);
                    //Display link to headers page
                    HeaderHypLink.Visible = true;
                    LogInButton.Visible = false;

                    Customer cust = new Customer(cookie["UserName"]);
                    if (cust.Exists)
                    {
                        lblCookie.Text = "Cookie: " + cookie["UserName"];
                        lblCustomerid.Text = "Customer ID: " + cust.CustomerID.ToString();
                        lblFirstname.Text = "First Name: " + cust.FirstName;
                        lblLastname.Text = "Last Name: " + cust.LastName;

                        lblCustomerid.Visible = true;
                        lblFirstname.Visible = true;
                        lblLastname.Visible = true;
                        lblCookie.Visible = true;
                    }
                }
                else
                {
                    HeaderHypLink.Visible = false;
                }
            }


            // only run on first page load.
            if (!IsPostBack)
            {

            }
            //Decoding/Encoding: http://stackoverflow.com/questions/11743160/how-do-i-encode-and-decode-a-base64-string
            //Cookie info: https://msdn.microsoft.com/en-us/library/ms178194.aspx
        }
        //Login button code (when clicked)
        protected void LogInButton_Click(object sender, EventArgs e)
        {
            lblCookie.Visible = false;
            lblCustomerid.Visible = false;
            lblFirstname.Visible = false;
            lblLastname.Visible = false;
            lblStatus.Visible = false;

            //Extract the username from the textbox at a maximum of 16 characters/letters
            string usernameText = username.Text.Trim();
            string passwordText = password.Text.Trim();

            //Check if the username or password textboxes were empty
            if (usernameText == string.Empty || passwordText == string.Empty)
            {
                lblStatus.Text = "username and password required";
                lblStatus.Visible = true;
                return;
            }

            //Database stuff
            string connectionString = WebConfigurationManager.ConnectionStrings["pubs"].ConnectionString;
            SqlConnection con = new SqlConnection(connectionString);
            try
            {
                con.Open();

                SqlCommand checkUserPass = new SqlCommand();
                checkUserPass.Connection = con;
                checkUserPass.CommandText = "SELECT customerid FROM customers WHERE username=@user AND password=@pass";
                checkUserPass.Parameters.AddWithValue("@user", usernameText);
                checkUserPass.Parameters.AddWithValue("@pass", passwordText);

                SqlDataReader reader = checkUserPass.ExecuteReader();

                // if an entry exists with the specified username and password
                if (reader.Read())
                {
                    //Encode the username so that we can use it as a value for the cookie
                    string encodedText;
                    encodedText = generateEncoding(usernameText);

                    HttpCookie cookie = Request.Cookies["Login"];
                    if (cookie == null)
                    {
                        cookie = new HttpCookie("Login");
                    }

                    cookie["UserName"] = encodedText;
                    cookie.Expires = DateTime.Now.AddDays(7);
                    Response.Cookies.Add(cookie);

                    //Display link to headers page
                    HeaderHypLink.Visible = true;

                    username.Text = Decode(cookie["UserName"]);

                    int customerID = (int)reader["customerid"];
                    reader.Close();
                    SqlCommand insertCookie = new SqlCommand();
                    insertCookie.Connection = con;
                    insertCookie.CommandText = "INSERT INTO sessions (customerid, cookie)"
                        + " VALUES (@custID, @cookie)";
                    insertCookie.Parameters.AddWithValue("@custID", customerID);
                    insertCookie.Parameters.AddWithValue("@cookie", encodedText);
                    insertCookie.ExecuteNonQuery();

                    Customer cust = new Customer(cookie["UserName"]);
                    if (cust.Exists)
                    {
                        lblCookie.Text = "Cookie: " + cookie["UserName"];
                        lblCustomerid.Text = "Customer ID: " + cust.CustomerID.ToString();
                        lblFirstname.Text = "First Name: " + cust.FirstName;
                        lblLastname.Text = "Last Name: " + cust.LastName;

                        lblCustomerid.Visible = true;
                        lblFirstname.Visible = true;
                        lblLastname.Visible = true;
                        lblCookie.Visible = true;
                    }

                    LogInButton.Visible = false;
                }
                else
                {
                    lblStatus.Visible = true;
                    lblStatus.Text = "Username or password doesn't exist.";
                    return;
                }
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
            }
            finally
            {
                con.Close();
            }

        }

        //Takes in the username and spits it back out as a return value
        private string generateEncoding(string text)
        {
            // Adds some noise characters to the beginning
            text = generateNoiseCharacters() + text;
            var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(text);
            return Convert.ToBase64String(plainTextBytes);
        }

        private string Decode(string encodedText)
        {
            try
            {
                var base64EncodedBytes = Convert.FromBase64String(encodedText);

                string decoded = System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
                decoded = decoded.Substring(3);
                return decoded;
            }
            catch(Exception)
            {
                Response.Write("Your user setting were weird: " + encodedText);
                return "";
            }
        }

        private static string generateNoiseCharacters(int length = 3)
        {
            Random random = new Random();

            const string chars = "ABCDEFGHIJKLMNOPQRSTUBWXYZ12345678I90!#$%^&*()-=_+/.,;'?><";
            // select length amount of random characters from the chars string, and return those.
            return new string(Enumerable.Repeat(chars, length).Select(s => s[random.Next(s.Length)]).ToArray());
        }
    }
}