Lab 4.4 (Delphi)

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    Label1: TLabel;
    MainMenu1: TMainMenu;
    SaveDialog1: TSaveDialog;
    OpenDialog1: TOpenDialog;
    PopupMenu1: TPopupMenu;
    File1: TMenuItem;
    Task: TMenuItem;
    Inst: TMenuItem;
    Dev: TMenuItem;
    OpenF: TMenuItem;
    SaveF: TMenuItem;
    N1: TMenuItem;
    Out: TMenuItem;
    procedure Button1Click(Sender: TObject);
    procedure Edit1KeyPress(Sender: TObject; var Key: Char);
    procedure Edit1Change(Sender: TObject);
    procedure OpenFClick(Sender: TObject);
    procedure SaveFClick(Sender: TObject);
    procedure TaskClick(Sender: TObject);
    procedure InstClick(Sender: TObject);
    procedure DevClick(Sender: TObject);
    procedure OutClick(Sender: TObject);
    procedure FormCloseQuery(Sender: TObject; var CanClose: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

const
    MAX = 50;

var
  Form1: TForm1;
  Path: String;
  IsFileOpen: Boolean;

implementation

{$R *.dfm}


Function F(Str: String): String;
Var p: Integer;
Begin
    p := pos('baba', Str);
    If p > 0 Then delete(Str, p, 2);
    if p = 0 then Result := Str
    Else
        Result := F(Str);
End;


procedure TForm1.Button1Click(Sender: TObject);
var
    Text: String;
begin
    Text := Edit1.Text;
    Label1.Caption := F(Text);
    Label1.Visible := True;
end;

procedure TForm1.DevClick(Sender: TObject);
begin
    Application.MessageBox('Symonik Vadim, 251004', 'Developer', 0);
end;

procedure TForm1.Edit1Change(Sender: TObject);
begin
    Label1.Visible := False;
    If Length(Edit1.Text) = 0 Then
        Button1.Enabled := False
    Else
        Button1.Enabled := True;
    If Length(Edit1.Text) > MAX Then
        Application.MessageBox('The maximum length of the string is 50 characters', 'Notification', 0)
end;

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
begin
    If not (Key in ['a', 'b', 'c', 'A', 'B', 'C',  #8, #13]) Then
        Key := #0;
    If (Key = #13) And (Button1.Enabled = True) Then
        Button1.Click;
end;

procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
    CanClose := MessageDlg('Do you really want to get out?', mtConfirmation, [mbYes,mbNo], 0)= IDYes
end;

procedure TForm1.InstClick(Sender: TObject);
const
    Str1 = '1. Enter only the characters A, B and C.';
    Str2 = #13#10'2. The maximum string length is 50 characters.';
    Str3 = #13#10'3. When entering values from a file, they must meet the above conditions.';

begin
    Application.MessageBox(Str1 + Str2 + Str3, 'Instruction', 0);
end;

Function Open() : String;
begin
    with Form1 Do
    begin
        If SaveDialog1.Execute Then
        begin
            Path := SaveDialog1.FileName;
            IsFileOpen := True;
        end
        Else
            IsFileOpen := False;
    end;
    Open := Path;
end;


Function GetLineFromF(Var FileInput: TextFile): String;
Var
    I: Integer;
    Str: String;
    IsCorrect: Boolean;
Begin
    IsCorrect := True;
    If Not Eof(FileInput) Then
    Begin
        Try
            Read(FileInput, Str);
        Except
            MessageBox(Form1.Handle, PChar('Invalid data'), 'Error', MB_ICONSTOP);
            Str := '';
            IsCorrect := False;
        End;
        If Not(IsCorrect) and (Length(Str) > MAX) Then
        Begin
            MessageBox(Form1.Handle, PChar('The maximum length of the string is 50 characters'), 'Error', MB_ICONSTOP);
            Str := '';
            IsCorrect := False;
        End;
        For I := 1 to Length(Str) do
        Begin
            If (Str[I] <> 'A') And (Str[I] <> 'B') And (Str[I] <> 'C') And (Str[I] <> 'a') And (Str[I] <> 'b') And (Str[I] <> 'c') Then
            Begin
                Str := '';
                MessageBox(Form1.Handle, PChar('Invalid data'), 'Error', MB_ICONSTOP);
            End;
        End;
    End
    Else
        MessageBox(Form1.Handle, PChar('Not enough data in the file!'), 'Error', MB_ICONSTOP);

    GetLineFromF := Str;
End;

procedure TForm1.OpenFClick(Sender: TObject);
var
    F: TextFile;
begin
    If OpenDialog1.Execute Then
    Begin
        AssignFile(F, OpenDialog1.FileName);
        Try
            Try
                Reset(F);
                Edit1.Text := GetLineFromF(F);
                If (Edit1.Text <> '') Then
                Begin
                    Button1.Click;
                End;
            Finally
                CloseFile(F);
            End;
        Except

        End;
    End;
end;

procedure TForm1.OutClick(Sender: TObject);
begin
    Form1.Close;
end;

procedure TForm1.SaveFClick(Sender: TObject);
var
    F: TextFile;
begin
    Path := Open;
    If IsFileOpen Then
    Begin
        AssignFile(F, Path);
        Rewrite(F);
        Writeln(F, Label1.Caption);
        Application.MessageBox('The data was saved successfully', 'Saving', 0);
        CloseFile(F);
    End;
end;

procedure TForm1.TaskClick(Sender: TObject);
const
    Str1 = 'The string of characters consists of the letters A, B and C.';
    Str2 = #13#10'Remove one pair of BA from the sequence of BABA.';
begin
    Application.MessageBox(Str1 + Str2, 'Task', 0);
end;

end.