unit uEditor;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Menus, Grids, StdCtrls;

type
  TfrmEditor = class(TForm)
    sgTable: TStringGrid;
    MainMenu: TMainMenu;
    Datei1: TMenuItem;
    Neu1: TMenuItem;
    ffnen1: TMenuItem;
    Speichernunter1: TMenuItem;
    N1: TMenuItem;
    Schlieen1: TMenuItem;
    SaveDialog: TSaveDialog;
    lblArticle_Number: TLabel;
    lblArticle_Description: TLabel;
    lblArticle_Price: TLabel;
    lblArticle_Category: TLabel;
    btnAdd: TButton;
    OpenDialog: TOpenDialog;
    procedure Neu1Click(Sender: TObject);

    procedure position(dataset : Integer);
    procedure btnAddClick(Sender: TObject);
    procedure Speichernunter1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure ffnen1Click(Sender: TObject);

  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

type Articles = record
  ID : Integer;
  Item : String[255];
  Category : String[255];
  Price : Integer;
end;

var
  frmEditor: TfrmEditor;
  rFile : file of Articles;

const
  BufferSize = 32;

implementation

{$R *.dfm}

procedure TfrmEditor.btnAddClick(Sender: TObject);
var
  Buffer : Array[0..BufferSize - 1] of Articles;
  i, p : Integer;
begin

// Tabelle erweitern

sgTable.RowCount := sgTable.RowCount + 1;

Seek(rFile, 0);
p := 0;

while not eof(rFile) do begin
  Read(rFile, Buffer[p]);
  inc(p);
end;

CloseFile(rFile);
Buffer[p + 1].ID := 0;
Buffer[p + 1].Item := '';
Buffer[p + 1].Category := '';
Buffer[p + 1].Price := 0;

Rewrite(rFile);

for i := 0 to p do Write(rFile, Buffer[i]);
position(FileSize(rFile)-1);

end;

procedure TfrmEditor.ffnen1Click(Sender: TObject);
var
  dataset : Articles;
  filename : String;
begin

if OpenDialog.Execute then
  begin
  filename := OpenDialog.filename;
  AssignFile(rFile, filename);
  end;

if FileExists(filename) then Reset(rFile);

position(0);
position(1);
position(2);

end;

procedure TfrmEditor.FormCreate(Sender: TObject);
begin
sgTable.Options + [goAlwaysShowEditor,goEditing];
sgTable.EditorMode := true;


end;

procedure TfrmEditor.Neu1Click(Sender: TObject);
var filename : String;
begin

if SaveDialog.Execute then
  begin

  filename := SaveDialog.Filename;
  AssignFile(rFile, filename);

  if FileExists(filename) then
    Reset(rFile)
  else Rewrite(rFile);

  end;

end;

procedure TfrmEditor.position(dataset : Integer);
var curDataset : Articles;
begin
  if (dataset < 0) or (dataset >= FileSize(rFile)) then exit else

    begin
    seek(rFile, dataset);
    read(rFile, curDataset);

    sgTable.Cells[0,dataset] := IntToStr(curDataset.ID);
    sgTable.Cells[1,dataset] := curDataset.Item;
    sgTable.Cells[2,dataset] := curDataset.Category;
    sgTable.Cells[3,dataset] := IntToStr(curDataset.Price);
    end;
  
end;

procedure TfrmEditor.Speichernunter1Click(Sender: TObject);
var
  dataset : Articles;
  pos : Integer;
begin
Seek(rFile, FilePos(rFile)-1);
pos := FilePos(rFile);
dataset.ID := StrToInt(sgTable.Cells[0, pos]);
dataset.Item := sgTable.Cells[1, pos];
dataset.Category := sgTable.Cells[2, pos];
dataset.Price := StrToInt(sgTable.Cells[3, pos]);

Write(rFile, dataset);
position(pos);
end;

end.