3_2 1

program Laba_3_2;
{$APPTYPE CONSOLE}
uses
   SysUtils;
type
   TInputChoice = (WithFile, Console);
   TSet = set of Char;

const
   InstructionMessage
      = 'This program composes a set consisting of arithmetic operands and even digits';
   WayOfInputMessage = 'Where do you want to input data from? [F]ile or [C]onsole?';
   IncorrectInputFilePath = 'Incorrect input file path, check if file exists and try again';
   IncorrectWayOfInputMessage = 'Incorrect way of input, choose [F]ile or [C]onsole';
   OutputFileExistsErrorMessage = 'Incorrect output file, such file already exists, try again';
   Mask = '-+*/02468';

function GetInputFilePath(): string;//ïðîâåðêà íà ïóñòîòó
var
   Path: string;
begin
   Writeln('Enter input file path');
   Readln(Path);
   while not FileExists(Path) do
   begin
      Writeln(IncorrectInputFilePath);
      Readln(Path);
   end;
   GetInputFilePath := Path;
end;

function GetOutputFilePath(): string;
var
   Path: string;
begin
   Writeln('Enter output file path');
   Readln(Path);
   while FileExists(Path) do
   begin
      Writeln(OutputFileExistsErrorMessage);
      Readln(Path);
   end;
   GetOutputFilePath := Path;
end;

function ChooseInputFromFileOrConsole(): TInputChoice;
var
   Choice: string;
begin
   Writeln(WayOfInputMessage);
   Readln(Choice);
   while (LowerCase(Choice) <> 'c') and (LowerCase(Choice) <> 'f') do
   begin
      Writeln(IncorrectWayOfInputMessage);
      Readln(Choice);
   end;

   if LowerCase(Choice) = 'f' then
      ChooseInputFromFileOrConsole := WithFile
   else
      ChooseInputFromFileOrConsole := Console;
end;

function GetStringFromFile(InputFilePath: string): string;
var
   InputFile: TextFile;
   InputString: string;
begin
   AssignFile(InputFile, InputFilePath);
   Reset(InputFile);
   Readln(InputFile, InputString);
   CloseFile(InputFile);
   GetStringFromFile := InputString;
end;

function GetStringFromConsole(): string;
var
   InputString: string;
begin
   Readln(InputString);
   GetStringFromConsole := InputString;
end;


function GetSetFromString(InputString: string): TSet;
var
   StringLength, i: Integer;
   Sequence: TSet;
begin
   Sequence := [];
   StringLength := Length(InputString);
   for i := 1 to StringLength do
      if (Pos(InputString[i], Mask) <> 0) and not(InputString[i] in Sequence) then
         Include(Sequence, InputString[i]);
   GetSetFromString := Sequence;
end;

procedure PrintSetToConsole(Sequence: TSet);
var
   i: Integer;
begin
   if Sequence = [] then
      Writeln('Your sequence doesn''t contain any of assumed symbols')
   else
   begin
      Writeln('Composed set based on your sequence');
      for i := 0 to 255 do
         if Chr(i) in Sequence then
            Write(Chr(i), ' ');
   end;
end;

procedure PrintSetToFile(Sequence: TSet; OutputFilePath: string);
var
   i: Integer;
   OutputFile: TextFile;
begin
   AssignFile(OutputFile, OutputFilePath);
   Rewrite(OutputFile);
   if Sequence = [] then
      Writeln(OutputFile, 'Your sequence doesn''t contain any of assumed symbols')
   else
   begin
      Writeln(OutputFile, 'Composed set based on your sequence');
      for i := 0 to 255 do
         if Chr(i) in Sequence then
            Write(OutputFile, Chr(i), ' ');
   end;
   CloseFile(OutputFile);
end;

procedure PrintSet(Sequence: TSet; OutputFilePath: string);//ïîäóìàòü íóæíà ëè òàêàÿ ôöèÿ
begin
   PrintSetToConsole(Sequence);
   PrintSetToFile(Sequence, OutputFilePath);
end;

procedure Main();
var
   InputFilePath, OutputFilePath, InputString: string;
   SequenceString: TSet;
begin
   Writeln(InstructionMessage);
   if ChooseInputFromFileOrConsole = WithFile then
   begin
      InputFilePath := GetInputFilePath();//ìîæíî çàñóíóòü â íèæíþþ ôöèþ
      InputString := GetStringFromFile(InputFilePath);
      OutputFilePath := GetOutputFilePath();
      SequenceString := GetSetFromString(InputString);
      PrintSet(SequenceString, OutputFilePath);
   end
   else
   begin
      Writeln('Input sequence of symbols');
      InputString := GetStringFromConsole();
      SequenceString := GetSetFromString(InputString);
      PrintSetToConsole(SequenceString);
   end;
   Readln;
end;

begin
   Main();
end.