program Project17;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils;

procedure ReadFileName(var MyFile: TextFile);
var
   FName: string;
   CorrectName: Boolean;
begin
   Writeln('Enter a file name for data entry in the format Name.txt');
   repeat
      Readln(FName);
      if FileExists(FName) then
         CorrectName := True
      else
      begin
         Writeln('The file name was entered incorrectly. Try again. Example: Name.txt');
         CorrectName := False;
      end;
   until CorrectName;
   AssignFile(MyFile, FName);
   Reset(MyFile);
end;

function FileCheck(var Words: String) : Boolean;
var
   FName: String;
   IsCorrect: Boolean;
   InputFile: TextFile;
   TrueString, IsValidInput: Boolean;
begin
   Assign(InputFile, FName);
   Reset(InputFile);
   TrueString := True;
   while not EOF (Inputfile) do
   begin
      try
         Read(InPutFile, Words);
      except
         TrueString := False;
      end;
   end;
   if Eof(InputFile) then
      IsValidInput := True
   else
      Writeln('File is empty.');
   Reset(InputFile);
   Writeln(Words);
   FileCheck := TrueString;
end;
procedure LongestWord(var Words: String);
Var
   i, j, k, Max: Integer;
   Line: String;
begin
   i := 1;
   Max := 0;
   repeat;
      j := 0;
      While (Words[i] <> ' ') and (i <= length(Words)) do
      begin
         Inc(i);
         Inc(j);
      end;
      if j > Max then
      Max := j;
      Inc(i);
   until i > length(Words);
   Writeln(Max);
   i := 1;
   repeat;
      j := 0;
      while (Words[i] <> ' ') and (i <= length(Words)) Do Begin
         Line := Line + Words[i];
         Inc(i);
      end;
      if length(Line) = Max then
          Writeln(Line);
          Line := '';
          Inc(i);
   until i > length(Words);
end;

procedure ReadFileOutputName(var MyFile: TextFile);
var
   NewFName: string;
   CorrectName: Boolean;
begin
   Writeln('Enter a file name for data entry in the format Name.txt');
   repeat
      Readln(NewFName);
      if Copy(NewFName, length(NewFName) - 3, 4) = '.txt' then
         CorrectName := True
      else
      begin
         Writeln('The file name was entered incorrectly. Try again. Example: Name.txt');
         CorrectName := False;
      end;
   until CorrectName;
   AssignFile(MyFile, NewFName);
   Rewrite(MyFile);
end;

procedure WriteToFile();
var
   LongWord: String;
   FName: String;
   OutFile: Text;
begin
   Assign(OutFile, FName);
   Rewrite(OutFile);
   Writeln(OutFile, 'The longesr word or words:' + LongWord);
   Close(OutFile);
end;

var
   Words: String;
   MyFile: TextFile;
   CorrectFile : Boolean;
begin
   Writeln('This program finds the longest word in the string.');
   ReadFileName(MyFile);
   CorrectFile := FileCheck(Words);
   Writeln('Your string: ');
   Writeln(Words);
   Writeln('');
   Writeln('The longest word or several words:');
   LongestWord(Words);
   ReadFileOutputName(MyFile);
   WriteToFile();
   Readln;
end.