lab3_2_1

Program lab3_2;

{$APPTYPE CONSOLE}

uses
    System.SysUtils;
type
    TChar = set of char;

Function InputFileLocation(): string;
Var
    IsCorrect: Boolean;
    Location: String;
Begin
    Repeat
        IsCorrect := false;
        WriteLn('Enter file location:');
        ReadLn(Location);
        If FileExists(Location) then
            IsCorrect := true
        Else
        Begin
            WriteLn('Please enter the correct location');
            WriteLn('');
        End;
    Until IsCorrect;
    InputFileLocation := Location;
End;


Function ChooseInput(): integer;
Var
    Line: String;
    IsCorrect: Boolean;
Begin
    Repeat
        IsCorrect := true;
        WriteLn('Do you want to input from file? (y/n)');
        ReadLn(line);
        Line := Line.ToLower();
        If(Line <> '') and (Line <> 'y') and (Line <> 'n') then
        Begin
            IsCorrect := false;
            WriteLn('Enter valid answer');
        End;
    Until IsCorrect;
    If (Line = '') or (Line = 'y') then
        ChooseInput := 0
    Else
        ChooseInput := 1;
End;

Procedure OutputToFile(Str: String);
var
    TFile: TextFile;
begin
    AssignFile(TFile, InputFileLocation());
    Rewrite(TFile);
    Write(TFile, Str);
    CloseFile(TFile);
end;

Function CheckUnique(Str: String; I: Integer; LetSet: TChar): Boolean;
Var
    IsNotUnique: Boolean;
Begin
    isNotUnique := false;
    If Str[I] in LetSet then
        isNotUnique := true
    else
        isNotUnique := false;
    CheckUnique := isNotUnique;
End;

Procedure ChangeSentence(var Str: String);
var
    Temp, I: Integer;
    IsNotUnique: Boolean;
    LetSet: TChar;
Begin
    LetSet := [];
    I := 1;
    Temp := High(Str);
    while I <= Temp do
    Begin
        isNotUnique := true;
        IsNotUnique := CheckUnique(Str, I, LetSet);
        if IsNotUnique then
        Begin
            Delete(Str, I, 1);
            Dec(Temp);
        End
        Else
        Begin
            LetSet := LetSet + [Str[I]];
            Inc(I);
        End;
    End;
End;

Function GetLineFromConsole(): String;
var
    IsCorrect: Boolean;
    Str: String;
begin
     repeat
        IsCorrect := true;
        ReadLn(Str);
        if Length(Str) = 0 then
        begin
            WriteLn('The line is empty, please, try to enter it one more time');
            IsCorrect := false;
        end;
    until IsCorrect;
    GetLineFromConsole := Str;
end;

Procedure GetLineFromFile(Str: String);
var IsCorrect: Boolean; TFile: TextFile;
begin
    repeat
        IsCorrect := true;
        AssignFile(TFile, InputFileLocation());
        Reset(TFile);
        ReadLn(TFile, Str);
        CloseFile(TFile);
        if (Length(Str) = 0) then
        begin
            WriteLn('String is empty. Enter another file location');
            IsCorrect := false;
        end;
    until IsCorrect;
end;

Procedure Main();
Var
    ChosenInput: Integer;
    Str: String;
    Size, I : Integer;
    isNotUnique : Boolean;
    LetSet : TChar;
Begin
    WriteLn('Программа удаляет одинаковые буквы в предложении.');
    ChosenInput := ChooseInput();
    If (ChosenInput = 0) then
        GetLineFromFile(Str)
    Else
        Begin
        writeln('Введите строку');
        Str := GetLineFromConsole();
        End;
    ChangeSentence(Str);
    writeln('Modified string');
    writeln(Str);
    WriteLn;
    OutputToFile(Str);
    ReadLn;
End;

Begin
    Main();
End.