using System;
using System.Data.SQLite;
using System.Security.Cryptography;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        string connectionString = "Data Source=users.db;Version=3;";
        
        // ایجاد دیتابیس و جدول در صورت نیاز
        InitializeDatabase(connectionString);

        Console.WriteLine("1. ثبت نام");
        Console.WriteLine("2. ورود");
        Console.Write("انتخاب: ");
        var choice = Console.ReadLine();

        if (choice == "1")
        {
            RegisterUser(connectionString);
        }
        else if (choice == "2")
        {
            LoginUser(connectionString);
        }
        else
        {
            Console.WriteLine("انتخاب نامعتبر است.");
        }
    }

    static void InitializeDatabase(string connectionString)
    {
        using (var connection = new SQLiteConnection(connectionString))
        {
            connection.Open();
            string createTableQuery = @"
                CREATE TABLE IF NOT EXISTS Users (
                    Id INTEGER PRIMARY KEY AUTOINCREMENT,
                    Username TEXT NOT NULL UNIQUE,
                    PasswordHash TEXT NOT NULL
                )";
            using (var command = new SQLiteCommand(createTableQuery, connection))
            {
                command.ExecuteNonQuery();
            }
        }
    }

    static void RegisterUser(string connectionString)
    {
        Console.Write("نام کاربری: ");
        string username = Console.ReadLine();
        Console.Write("رمز عبور: ");
        string password = Console.ReadLine();

        string passwordHash = HashPassword(password);

        using (var connection = new SQLiteConnection(connectionString))
        {
            connection.Open();
            string insertQuery = "INSERT INTO Users (Username, PasswordHash) VALUES (@Username, @PasswordHash)";
            using (var command = new SQLiteCommand(insertQuery, connection))
            {
                command.Parameters.AddWithValue("@Username", username);
                command.Parameters.AddWithValue("@PasswordHash", passwordHash);

                try
                {
                    command.ExecuteNonQuery();
                    Console.WriteLine("ثبت نام موفقیت‌آمیز بود.");
                }
                catch (SQLiteException ex)
                {
                    Console.WriteLine("خطا: " + ex.Message);
                }
            }
        }
    }

    static void LoginUser(string connectionString)
    {
        Console.Write("نام کاربری: ");
        string username = Console.ReadLine();
        Console.Write("رمز عبور: ");
        string password = Console.ReadLine();

        string passwordHash = HashPassword(password);

        using (var connection = new SQLiteConnection(connectionString))
        {
            connection.Open();
            string selectQuery = "SELECT COUNT(*) FROM Users WHERE Username = @Username AND PasswordHash = @PasswordHash";
            using (var command = new SQLiteCommand(selectQuery, connection))
            {
                command.Parameters.AddWithValue("@Username", username);
                command.Parameters.AddWithValue("@PasswordHash", passwordHash);

                int count = Convert.ToInt32(command.ExecuteScalar());
                if (count > 0)
                {
                    Console.WriteLine("ورود موفقیت‌آمیز بود.");
                }
                else
                {
                    Console.WriteLine("نام کاربری یا رمز عبور اشتباه است.");
                }
            }
        }
    }
static string HashPassword(string password)
    {
        using (SHA256 sha256 = SHA256.Create())
        {
            byte[] bytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(password));
            StringBuilder builder = new StringBuilder();
            foreach (var b in bytes)
            {
                builder.Append(b.ToString("x2"));
            }
            return builder.ToString();
        }
    }
}