[Setup]
AppName=My Program
AppVersion=1.5
DefaultDirName={pf}\My Program
AlwaysRestart=no
DisableFinishedPage=yes

 
[CustomMessages]
restart_Caption0=Yes restart now
restart_Caption1=No restart later


[Code]
var
    RestartRadioButton: TRadioButton;
    PostponeRestartRadioButton: TRadioButton;
    Page: TWizardPage;
    FirstLabel: TLabel;
    FirstLabelB: TLabel;
    LabelText: string;
    LabelTextB: string;

    
function NeedRestart(): Boolean;
begin
  Result := True;
end; 

function authentication_form_NextButtonClick(Page: TWizardPage): Boolean;
begin
  if PostponeRestartRadioButton.Checked then
  begin
    MsgBox('The computer needs to be restarted before Setup can continue.', mbError, MB_OK);
    RestartRadioButton.Checked := True
    Result := False;
  end
  else
  begin
    NeedRestart();
    Result := True;
  end
end;

function CreateDataPage(PreviousPageId: Integer): Integer;   
begin
  if (FileExists('C:\Windows\System32\bash.exe')) then
  begin
      LabelText := 'WSL is already installed.'
  end
  else
  begin
      LabelText := 'WSL was installed.'
  end;

  LabelTextB := 'The computer needs to be restarted before Setup can continue.'

  Page :=CreateCustomPage(PreviousPageId,'WSL installation', '');


    FirstLabel :=TLabel.Create(Page);
    with FirstLabel do
    begin
        Parent :=Page.Surface;
        Caption :=ExpandConstant(LabelText);
        Left :=ScaleX(16);
        Top :=ScaleY(50);
        Width :=ScaleX(250);
        Height :=ScaleY(17);
    end;

    FirstLabelB :=TLabel.Create(Page);
    with FirstLabelB do
    begin
        Parent :=Page.Surface;
        Caption :=ExpandConstant(LabelTextB);
        Left :=ScaleX(16);
        Top :=ScaleY(84);
        Width :=ScaleX(500);
        Height :=ScaleY(17);
    end;

    RestartRadioButton := TRadioButton.Create(Page);
    with RestartRadioButton do
    begin
        Parent := Page.Surface;
        Caption := ExpandConstant('{cm:restart_Caption0}');
        Left := ScaleX(16);
        Top := ScaleY(112);
        Width := ScaleX(193);
        Height := ScaleY(17);
        TabOrder := 2;
        Checked := true;
    end;

    PostponeRestartRadioButton := TRadioButton.Create(Page);
    with PostponeRestartRadioButton do
    begin
        Parent := Page.Surface;
        Caption := ExpandConstant('{cm:restart_Caption1}');
        Left := ScaleX(16);
        Top := ScaleY(140);
        Width := ScaleX(193);
        Height := ScaleY(17);
        TabOrder := 2;
    end;

    with Page do
    begin
       OnNextButtonClick := @authentication_form_NextButtonClick;
       if PostponeRestartRadioButton.Checked then
       begin
         RestartRadioButton.Checked := false
       end;
       if RestartRadioButton.Checked then
       begin
         PostponeRestartRadioButton.Checked := false
       end;
    end;

    Result :=Page.ID;

end;

procedure InitializeWizard();
begin
    CreateDataPage(wpInstalling);
end;

procedure CurPageChanged(CurPageID: Integer);
begin
  if CurPageID = Page.ID then begin
    WizardForm.NextButton.Caption := 'Finish'  
  end;
end;