unit UnitLogin;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls, Main, UnitNewUser;

type
  TfrmLogin = class(TForm)
    btnLogin: TButton;      // btn prefix = button
    lbledtUsername: TLabeledEdit; // lbledt = label that data can be inputted into while program is running
    lbledtPassword: TLabeledEdit;
    btnAdd_New_User: TButton;
    lblLoginSuccessful: TLabel; // lbl prefix = label containing data
    btnContinue: TButton;
    lblMessage: TLabel;
    btnLogout: TButton;
    procedure btnLoginClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure btnAdd_New_UserClick(Sender: TObject);
    procedure btnContinueClick(Sender: TObject);
    procedure btnLogoutClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    Username,Password : string;
    Userfile : textfile;
    TextString : string;
  end;

var
  frmLogin: TfrmLogin;


implementation
{$R *.dfm}

procedure TfrmLogin.FormCreate(Sender: TObject);
begin
  lblMessage.show;
  lbledtUsername.show;
  lbledtPassword.show;
  btnAdd_New_user.show;
  btnLogin.show;

  lblLoginSuccessful.hide;
  btnContinue.hide;
  btnlogout.hide;
end;

procedure TfrmLogin.btnAdd_New_UserClick(Sender: TObject);
begin
  FormNewUser.Show;   //show new user form
end;

procedure TfrmLogin.btnContinueClick(Sender: TObject);
begin
   FormMainMenu.Show;    //show quiz menu
end;

procedure TfrmLogin.btnLoginClick(Sender: TObject);
Var closing,found, Endendof,incpass : boolean;
begin
  Closing := false;
  Found := false;
  endendof := false;
  incPass:= false;
  Username := lbledtUsername.Text;
  Password := lbledtPassword.Text;

  AssignFile(Userfile, 'Usernames.txt') ;   //open and read Usernames file
  Reset(Userfile);
  while (Closing = false) do
  begin
  readln(Userfile,textstring);     //read file line by line
  if (textstring = Username) then  //compare username stored in file to value entered in the username box
  begin
    readln(Userfile,textstring);
    if (textstring = password) then  //compare password under that username stored in file to value entered in the password box
    begin
      lbledtUsername.Hide;     //Hide Username Box
      lbledtPassword.Hide;     //Hide Password Box
      lblMessage.Hide;
      btnLogOut.Show;
      btnAdd_New_user.Hide;    //Hide the Button to add new user
      btnLogin.Hide;           //Hide Button the check login details
      btnContinue.Show;
      lblLoginSuccessful.Show;
      closing := true;
      found := true;
    end
else
 begin
    closing := true;
      Showmessage('Incorrect Password');     //Displaying error message
      incPass:=true;
    end;
  end;

  end;

  if (Found = false) then
  begin
     closing := true;
    if (incpass=false) then
    begin
    Showmessage('Incorrect Username');
    end;
    Found := true;
  end;


  closefile(UserFile);
end;



procedure TfrmLogin.btnLogoutClick(Sender: TObject);  //returns to orignal login layout
begin
    lbledtUsername.Show;
      lbledtPassword.show;
      btnAdd_New_user.show;
      btnLogin.show;
      lblLoginSuccessful.hide;
      btnContinue.Hide;
      btnlogout.Hide;
      lblMessage.Show;
      lbledtUsername.Text:='';
      lbledtPassword.Text:='';
end;

end.

NEW USER Module

unit UnitNewUser;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;

type
  TFormNewUser = class(TForm)
    lbledtNew_Username: TLabeledEdit;
    lbledtNew_Password: TLabeledEdit;
    btnNew_User: TButton;
    procedure btnNew_UserClick(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
     UserFile : TextFile  ;
     Textstring: String;
  end;

var
  FormNewUser: TFormNewUser;

implementation

{$R *.dfm}


procedure TFormNewUser.btnNew_UserClick(Sender: TObject);
var ended, used: boolean;
    usrnm, pswrd: string;

begin
usrnm:= lbledtNew_Username.Text;         //read in username entered in box
pswrd:= lbledtNew_Password.Text;         //read in password entered in box
ended:=false;
  Used:=False;
  AssignFile(UserFile, 'Usernames.txt'); //open usernames folder (usernames file has passwords in it)
  {$I-}
  Reset(UserFile);
  {$i+}
  while (* not EOF(UserFile) or ( *) ended=false do
  Begin
      Readln(UserFile, TextString);    //checking for duplicate usernames
      If (Textstring = Usrnm) then
      begin
         ended:=true;
         Used:=True;
           Showmessage('Username is taken');  //display error message
      end
      else

      Readln(UserFile, TextString);         //read in username and store it in file
          if EOF(UserFile) then
      begin
      ended := True;                       //tell program it is at the end of the file
      end;

  End;
   CloseFile(UserFile);

  if (Used=false) then                         //if username has not been used before
  begin
  AssignFile (UserFile, 'Usernames.txt');      //create usernames folder
  Append(UserFile);
  Writeln(UserFile, UsrNm);                    //write username entered to file
  Writeln(UserFile, Pswrd);                    //write password entered to file
  CloseFile(UserFile);
Showmessage('Succesfully registered!');
close;
   end

else                                       //if no usernames and passwords have already been asigned
   begin
     lbledtNew_Username.Text := 'Username';   //create default username and password

     lbledtNew_Password.PasswordChar := #0 ;
     lbledtNew_Password.Text := 'Password';
     CloseFile(UserFile);

   end
end;