using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace PassLockBetter
{
    class Program
    {
        static string UserName;
        static string Password;

        static List<string> accounts = new List<string>();
        static List<string> userNames = new List<string>();

        static int counter = 0;

        static void Main(string[] args)
        {
            Start();
        }

        static void Start()
        {
            Console.WriteLine("Type 'REGISTER' to register a new account or type 'LOGIN' to login to your existing account");
            string LOR = Console.ReadLine();

            if (LOR == "LOGIN")
            {
                Login();
            }

            if (LOR == "REGISTER")
            {
                Register();
            }
        }

        static void Register()
        {
            bool UsrNameConf = false;
            bool PssWrdConf = false;

            Console.WriteLine("Please enter a username (4 characters minimum length and 12 characters maximum length)");
            string UN = Console.ReadLine();

            if (4 <= UN.Length && 12 >= UN.Length)
            {
                if (userNames.Contains(UN))
                {
                    Console.WriteLine("username already exists");
                    Register();
                }

                else
                {
                    UserName = UN;
                    UsrNameConf = true;
                }

            }

            else
            {
                Console.WriteLine("not a valid username");
                Start();
            }

            while (UsrNameConf && !PssWrdConf)
            {
                Console.WriteLine("enter a password (4 characters minimum length and 18 characters maximum length)");
                string PW = Console.ReadLine();
                if (PW.Length >= 4 && PW.Length <= 18)
                {
                    Password = PW;
                    PssWrdConf = true;
                }

                else
                {
                    Console.WriteLine("not a valid password");
                }
            }

            if (UsrNameConf && PssWrdConf)
            {
                userNames.Add(UserName);
                accounts.Add(UserName + Password);
                UserName = "";
                Password = "";
                Console.WriteLine("Account successfuly registered");
                Start();
            }
        }

        static void Login()
        {
            string PW;
            string UN;

            Console.WriteLine("Type in your username");
            UN = Console.ReadLine();
            Console.WriteLine("Type in your password");
            PW = Console.ReadLine();

            if (accounts.Contains(UN + PW))
            {
                Console.WriteLine("Welcome to your account " + UN);
                Start();
            }
            else
            {
                Console.WriteLine("Invalid password or username");
                counter += 1;

                if (counter == 3)
                {
                    Console.WriteLine("You are locked out. Wait for 10 seconds to continue ");
                    lockedWait();
                    Login();
                }
                else
                {
                    Login();
                }
            }
        }

        static void lockedWait()
        {
            System.Threading.Thread.Sleep(10000);           //1000 = 1 SECOND
        }
    }
}