unit Main;

interface

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

const
  NAVHOME = 0;
  NAVLOGIN = 1;
  NAVZOEKPRODUCTEN = 2;

type
  INavigator = interface
    ['{1648577B-6F43-4C3D-9122-F4F74D998611}']
    procedure NavigeerNaar(schermId: Integer);
  end;

  TControlArray = Array of TControl;

  TFormMain = class(TForm, INavigator)
    PanelMain: TPanel;
    procedure FormCreate(Sender: TObject);
    procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean);
  private
    FAppContext: TApplicationContext;
    FUserAgent: TUserAgent;
    FProductsAgent: TProductsAgent;
  public
    procedure NavigeerNaar(schermId: Integer);
  end;

  TCustomControl = Class(TControl)

  End;

var
  FormMain: TFormMain;

implementation

uses
  Util, LogInScherm, NavProductScherm;

{$R *.dfm}

// Dit event wordt altijd aangeroepen, OnClose niet
procedure TFormMain.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
  FUserAgent.GebruikerAfmelden(FAppContext.UserContext); // Antwoord wordt genegeerd
end;

procedure TFormMain.FormCreate(Sender: TObject);
begin
  FAppContext := TApplicationContext.Create();
  FUserAgent := TUserAgent.Create();
  FProductsAgent := TProductsAgent.Create();
  PanelMain.Parent := Self;
  PanelMain.Align := TAlign.alClient;

  Self.NavigeerNaar(NAVLOGIN);
end;

procedure TFormMain.NavigeerNaar(schermId: Integer);
var
  NieuwScherm: TControl;
begin
  Application.ProcessMessages; // Interrupts the execution of an application so that it can process the message queue.

  // Volgende subscherm laden in panel

  // PanelMain behouden we altijd, the children can be free.
  TUtil.FreeControlChildrenDeep(PanelMain);

  case schermId of
    NAVHOME, NAVZOEKPRODUCTEN:
      NieuwScherm := TFormProductNav.Create(PanelMain, Self, FAppContext, FUserAgent, FProductsAgent);
    NAVLOGIN:
      NieuwScherm := TFormLogin.Create(PanelMain, Self, FAppContext, FUserAgent);
  else
    Exception.Create('SchermID: ' + IntToStr(schermId) + ' is onbekend');
    NavigeerNaar(NAVHOME);
    exit;
  end;

  NieuwScherm.Parent := PanelMain;
  NieuwScherm.Align := alClient;
  NieuwScherm.Show;
end;

end.