program laba31;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils;

type
  Tset = set of Char;

procedure InputStringsFromConsole(var Str1: string; var Str2: string);

begin
  Writeln('Enter first string');
  Readln(Str1);
  Writeln('Enter second string');
  Readln(Str2);
end;

procedure InputStringsFromFile(var Str1: string; var Str2: string);

var
  IsCorrectInput: Boolean;
  UserFile: TextFile;
  FileName: String;

begin
  repeat
    IsCorrectInput := True;
    Writeln('Inter file location');
    Readln(FileName);
    if FileExists(FileName) then
    begin
      try
        Assign(UserFile, FileName);
        Reset(UserFile);;
      except
        Writeln('Ur File cant');
        IsCorrectInput := False
      end;
      if IsCorrectInput then
      begin
        if EoF(UserFile) then
        begin
          Writeln('File is empty, choose another file');
          IsCorrectInput := False;
        end
        else
        while not EoF(UserFile) do
        begin
          try
            Readln(UserFile, Str1);
            Readln(UserFile, Str2);
          except
            Writeln('Ivalid data, try again');
            IsCorrectInput := False;
          end;
        end;
        CloseFile(UserFile);
      end;
    end
    else
    begin
      Writeln('Ur file not found, try again');
      IsCorrectInput := False;
    end;
  until IsCorrectInput;
end;

procedure ChooseInput(var Str1: String; var Str2: String);

var
  Symbol: Char;
  IsCorrect: Boolean;

begin
  repeat
    IsCorrect := True;
    Writeln('If u want to input strings from console - enter "1"' + #10#13 + 'If u want to input strings from file - enter "2"' );
    Readln(Symbol);
    if (Symbol <> '1') and (Symbol <> '2') then
    begin
      Writeln('Ur input incorrect, try again');
      IsCorrect := False;
    end;
  until IsCorrect;
  if Symbol = '2' then
    InputStringsFromFile(Str1, Str2)
  else
    InputStringsFromConsole(Str1, Str2);
end;

procedure SetsOperations(OperationType: Char; Str1: string; Str2: string; var ResultSet: TSet);

var
  FirstSet: TSet;
  SecondSet: TSet;
  i: Integer;

begin
  FirstSet := [];
  SecondSet := [];
  ResultSet := [];
  for i := 1 to length(Str1) do
    FirstSet := FirstSet + [Str1 [i]];
  for i := 1 to length(Str2) do
    SecondSet := SecondSet + [Str2 [i]];
  if (OperationType = '1') then
  begin
    ResultSet := FirstSet * SecondSet
  end
  else
    ResultSet := (FirstSet + SecondSet) - (FirstSet * SecondSet);
end;

procedure OutputAnswerToConsole(AnswerSet: TSet);
var
  ch: Char;
begin
  if (AnswerSet = []) then
    WriteLn('Ur set is empty')
  else
  begin
    Writeln('Answer set is...');
    for ch := #0 to #255 do
      if (ch in AnswerSet) and (ch <> ' ') then
        Write(ch, ' ');
  end;
  Writeln;
end;

procedure OutputAnswerToFile(AnswerSet: TSet);

var
  IsCorrectOutput: Boolean;
  ResFile: TextFile;
  FileName: string;
  ch: Char;

begin
  repeat
    IsCorrectOutput := True;
    Writeln('Enter output file location');
    Readln(FileName);
    if FileExists(FileName) then
    begin
      try
        Assign(ResFile, FileName);
        Rewrite(ResFile);
      except
        Writeln('Ur file cant be opened');
        IsCorrectOutput := False;
      end;
      if IsCorrectOutput then
      begin
        if (AnswerSet = []) then
          Writeln(ResFile,'Подходящих значений нет.')
        else
        begin
          for ch := #0 to #255 do
            if (ch in AnswerSet)and (ch <> ' ') then
              WriteLn(ResFile, ch, ' ');
        end;
        Writeln('Successfully recorded');
        CloseFile(ResFile);
      end;
    end
    else
    begin
      Writeln('File not found, try again');
      IsCorrectOutput := False;
    end;
  until IsCorrectOutput;
end;

var
  FirstString, SecondString: String;
  IsCorrect: Boolean;
  OperationType: Char;
  ResultSet: TSet;

begin
  Writeln('Theme: Two lines are given. Develop a procedure that, accordingа'+ #10#13 +' to the value of the first parameter, performsа'+ #10#13 +' the following operations on these lines: itа'+ #10#13 +' finds characters that occur in both lines, finds characters that occur only in the first line, only in the second line.');
  ChooseInput(FirstString, SecondString);
  Writeln(FirstString);
  Writeln(SecondString);
  repeat
    WriteLn('Choose operation:' + #10#13 + 'Enter ''1'' to choose intercaption ' + #10#13 + 'Enter ''2'' to choose difference ');
    ReadLn(OperationType);
    case OperationType of
    '1': IsCorrect := True;
    '2': IsCorrect := True;
    else Writeln('Ur input incorrect, try again');
    end;
  until IsCorrect;
  SetsOperations(OperationType, FirstString, SecondString, ResultSet);
  OutputAnswerToConsole(ResultSet);
  Writeln('Do u want to save ur set in file? (Y/N)');
  IsCorrect := False;
  repeat
    Readln(OperationType);
    OperationType := UpCase(OperationType);
    case OperationType of
    'Y': IsCorrect := True;
    'N': IsCorrect := True;
    else Writeln('Ur input incorrect, try again');
    end;
  until IsCorrect;
  if OperationType = 'Y' then
    OutputAnswerToFile(ResultSet);
  Writeln('End of programm');
  Readln;
end.