unit MainUnit;

interface

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

type
   TMainForm = class(TForm)
      lbPrimeRoots: TListBox;
    lbAmount: TLabel;
    edP: TEdit;
    edX: TEdit;
    edK: TEdit;
    btEncrypt: TButton;
    OPenFile: TOpenDialog;
    MainMenu: TMainMenu;
    N1: TMenuItem;
    mnOpen: TMenuItem;
    mnSaveAs: TMenuItem;
    SaveFile: TSaveDialog;
    btDecipher: TButton;
    lbP: TLabel;
    lbX: TLabel;
    lbK: TLabel;
    lbShowRoots: TButton;
    mmCipher: TMemo;
    lbAmountText: TLabel;
    procedure FormCreate(Sender: TObject);
    procedure mnOpenClick(Sender: TObject);
    procedure btEncryptClick(Sender: TObject);
    procedure mnSaveAsClick(Sender: TObject);
    procedure btDecipherClick(Sender: TObject);
    procedure lbShowRootsClick(Sender: TObject);
   private
   const
      TempFileName = 'Temp\Temp';
   var
      SourceFileName: string;
      OutputFileName: string;
      ElgamalCipher: TElgamalCipher;

      procedure FillPrimeRoots(PrimeNumber: Integer);
      procedure ShowError(ErrorType: Integer);
      function RemoveAnnesSymbols(const InputStr: string): string;
   public
      procedure FillMemo(const NumbersArr: IntBuff; Len: Integer); overload;
      procedure FillMemo(const NumbersArr: ByteBuff; Len: Integer); overload;
   end;

var
  MainForm: TMainForm;

implementation

{$R *.dfm}

{ TMainForm }

procedure TMainForm.FormCreate(Sender: TObject);
begin
   ElgamalCipher := TElgamalCipher.Create;
   mmCipher.Clear;
end;

procedure TMainForm.lbShowRootsClick(Sender: TObject);
var
   PStr: string;
   P: Integer;
begin
   PStr := RemoveAnnesSymbols(edP.Text);
   if Length(PStr) <> 0 then
   begin
      try
         P := StrToInt(PStr);
      except
         Exit;
      end;
      if ElgamalCipher.IsPrime(P) then
         FillPrimeRoots(P)
      else
         ShowError(1);
   end;
end;

procedure TMainForm.btEncryptClick(Sender: TObject);
const
   NoFileMsg = 'Не выбран исходный файл.';
   NoFileCaption = 'Не выбран файл';
   SuccessText = 'Успешно зашифровано.';
   SuccessCaption = 'Зашифровано';
var
   ErrorIndex: Integer;
   PStr, XStr, KStr: string;
   P, X, K: Integer;
begin
   if FileExists(SourceFileName) then
   begin
      PStr := RemoveAnnesSymbols(edP.Text);
      XStr := RemoveAnnesSymbols(edX.Text);
      KStr := RemoveAnnesSymbols(edK.Text);
      if (Length(pStr) = 0) or (Length(XStr) = 0) or (Length(KStr) = 0) then
         Exit;
      try
         P := StrToInt(PStr);
         X := StrToInt(XStr);
         K := StrToInt(KStr);
      except
         Exit;
      end;
      ErrorIndex := ElgamalCipher.CheckNumbers(P, X, K);
      if ErrorIndex <> 0 then
      begin
         ShowError(errorIndex);
         Exit;
      end;
      if lbPrimeRoots.ItemIndex = -1 then
         Exit;
      OutputFileName := TempFileName + ExtractFileExt(SourceFileName);
      mmCipher.Clear;
      ElgamalCipher.EncryptFile(SourceFileName, OutputFileName,
         P, StrToInt(lbPrimeRoots.Items[lbPrimeRoots.ItemIndex]),
         ElgamalCipher.GetOpenKey(StrToInt(lbPrimeRoots.Items[lbPrimeRoots.ItemIndex]),
         X, P), K);
      MessageBox(Handle, SuccessText, SuccessCaption, MB_OK + MB_ICONINFORMATION);
   end
   else
      MessageBox(Handle, NoFileMsg, NoFileCaption, MB_OK + MB_ICONINFORMATION);
end;

procedure TMainForm.btDecipherClick(Sender: TObject);
const
   NoFileMsg = 'Не выбран исходный файл.';
   NoFileCaption = 'Не выбран файл';
   SuccessText = 'Успешно расшифровано.';
   SuccessCaption = 'Расшифровано';
var
   XStr, PStr: string;
   X, P, ErrorIndex: Integer;
begin
   if FileExists(SourceFileName) then
   begin
      PStr := RemoveAnnesSymbols(edP.Text);
      XStr := RemoveAnnesSymbols(edX.Text);
      if (Length(pStr) = 0) or (Length(XStr) = 0) then
         Exit;
      try
         P := StrToInt(PStr);
         X := StrToInt(XStr);
      except
         Exit;
      end;
      ErrorIndex := ElgamalCipher.CheckNumbers(P, X, 0);
      if (ErrorIndex <> 0) and (ErrorIndex <> 3) then
      begin
         ShowError(errorIndex);
         Exit;
      end;
      OutputFileName := TempFileName + ExtractFileExt(SourceFileName);
      mmCipher.Clear;
      ElgamalCipher.DecryptFile(SourceFileName, OutputFileName, X, P);
      MessageBox(Handle, SuccessText, SuccessCaption, MB_OK + MB_ICONINFORMATION);
   end
   else
      MessageBox(Handle, NoFileMsg, NoFileCaption, MB_OK + MB_ICONINFORMATION);
end;

procedure TMainForm.FillMemo(const NumbersArr: ByteBuff; Len: Integer);
const
   MaxAmount = 79;
var
   i: Integer;
begin
   Dec(Len);
   if Len > MaxAmount then
      len := MaxAmount;
   for i := 0 to Len do
      mmCipher.Text := mmCipher.Text + ' ' + IntToStr(NumbersArr[i]);
end;

procedure TMainForm.FillMemo(const NumbersArr: IntBuff; Len: Integer);
const
   MaxAmount = 79;
var
   i: Integer;
begin
   Dec(Len);
   if Len > MaxAmount then
      len := MaxAmount;
   for i := 0 to Len do
      mmCipher.Text := mmCipher.Text + ' ' + IntToStr(NumbersArr[i]);
end;

procedure TMainForm.FillPrimeRoots(PrimeNumber: Integer);
var
   PrimeRoots: TIntArray;
   i, Len: Integer;
begin
   lbPrimeRoots.Clear;
   PrimeRoots := ElgamalCipher.GetPrimeRoots(PrimeNumber);
   lbAmount.Caption := IntToStr(Length(PrimeRoots));
   Len := Length(PrimeRoots) - 1;
   if Len > 2000 then
      Len := 2000;
   for i := 0 to Len do
      lbPrimeRoots.Items.Add(IntToStr(PrimeRoots[i]));
end;

procedure TMainForm.ShowError(ErrorType: Integer);
const
   ErrorCaption = 'Ошибка';
   NotSimpleP = 'Число p должно быть простым и превышать 255.';
   WrongX = 'Число x должно принадлежать интервалу (1; p - 1).';
   WrongK = 'Число k должно быть взаимно простым с p - 1 и принадлежать интервалу (1; p - 1).';
begin
   case ErrorType of
      1: MessageBox(Handle, NotSimpleP, ErrorCaption, MB_OK + MB_ICONERROR);
      2: MessageBox(Handle, WrongX, ErrorCaption, MB_OK + MB_ICONERROR);
      3: MessageBox(Handle, WrongK, ErrorCaption, MB_OK + MB_ICONERROR);
   end;
end;

procedure TMainForm.mnOpenClick(Sender: TObject);
begin
    if OpenFile.Execute then
   begin
      SourceFileName := OpenFile.FileName;
      if FileExists(SourceFileName) then
      begin
         SourceFileName := SourceFileName;
//         lbCurrFileName.Caption := SourceFileName;
//         ClearGrid;
      end
      else
         SourceFileName := '';
   end;
end;

procedure TMainForm.mnSaveAsClick(Sender: TObject);
begin
   if FileExists(SourceFileName) and FileExists(OutputFileName) then
      if SaveFile.Execute then
      begin
         if ExtractFileExt(SaveFile.FileName) = ExtractFileExt(SourceFileName) then
            CopyFile(PChar(OutputFileName), PChar(SaveFile.FileName), false)
         else
            CopyFile(PChar(OutputFileName), PChar(SaveFile.FileName + ExtractFileExt(SourceFileName)), false);
      end;
end;

function TMainForm.RemoveAnnesSymbols(const InputStr: string): string;
const
   ValidSymbols = ['0'..'9'];
var
   i: Integer;
begin
   Result := '';
   for i := 1 to Length(InputStr) do
      if InputStr[i] in ValidSymbols then
         Result := Result + InputStr[i];
end;

end.