using System;
using System.Text;
using System.Linq;
using System.Collections.Generic;
using System.IO;
using System.Data.SqlClient;

namespace Server
{
    class UserManagment
    {
        static string ConnectionString = @"Data Source=.\SQLExpress;Initial Catalog=Account;Integrated Security=SSPI";

        static public bool Exists(string username, string password)
        {
            using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
            {
                sqlConn.Open();
                SqlCommand sc = new SqlCommand("SELECT * FROM tAccounts WHERE sUsername = @Username AND sUserPass = @Password", sqlConn);
                sc.Parameters.AddWithValue("@Username", username);
                sc.Parameters.AddWithValue("@Password", password);
                SqlDataReader dr = sc.ExecuteReader();

                if(dr.HasRows)
                    return true;
                else
                    return false;
            }
        }

        static private string UserData(string username, string info)
        {

            using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
            {
                sqlConn.Open();
                SqlCommand sc = new SqlCommand("SELECT * FROM tAccounts WHERE sUsername = @Username", sqlConn);
                sc.Parameters.AddWithValue("@Username", username);
                SqlDataReader dr = sc.ExecuteReader();
                dr.Read();

                return dr[info].ToString();
            }
        }

        static private string CreateToken(string nEMID)
        {
            using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
            {
                string token = TokenGenerate(30);
                sqlConn.Open();
                SqlCommand sc = new SqlCommand("INSERT INTO tTokens (nEMID, sToken) VALUES (@nEMID, @Token)", sqlConn);
                sc.Parameters.AddWithValue("@nEMID", nEMID);
                sc.Parameters.AddWithValue("@Token", token);
                sc.ExecuteScalar();

                return token;
            }
        }

        static public string Autentication(string username)
        {
            using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
            {
                sqlConn.Open();
                SqlCommand sc = new SqlCommand("SELECT nAuthID FROM tAccounts WHERE sUsername = @Username", sqlConn);
                sc.Parameters.AddWithValue("@Username", username);

                string AuthID = sc.ExecuteScalar().ToString();

                if (AuthID == "-1")
                {
                    return "-1";
                }
                else if (Auth().Contains(Convert.ToInt32(AuthID)))
                {
                    return CreateToken(UserData(username, "nEMID"));
                }
                else
                {
                    return "2";
                }
            }
        }

        static private int[] Auth()
        {
            List<int> AuthList = new List<int>();
            using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
            {
                sqlConn.Open();
                SqlCommand sc = new SqlCommand("SELECT nAuthID FROM tAuth WHERE nLoginable = @Loginable", sqlConn);
                sc.Parameters.AddWithValue("@Loginable", "1");

                SqlDataReader dr = sc.ExecuteReader();

                while (dr.Read())
                {
                    AuthList.Add(dr.GetInt32(0));
                }

                return AuthList.ToArray();
            }
        }

        static private readonly Random random = new Random();
        static private string chars = "ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvxyz123456789_.";

        static public string TokenGenerate(int size)
        {
            char[] buffer = new char[size];

            for (int i = 0; i < size; i++)
            {
                buffer[i] = chars[random.Next(chars.Length)];
            }
            return new string(buffer);
        }
    }
}