PROGRAM GuessANumber;

FUNCTION IsAnInt(input : STRING) : BOOLEAN;
VAR
	output,code:INTEGER;
BEGIN
	Val(input, output, code);
	IF code = 0 THEN
		RETURN TRUE
	ELSE
		RETURN FALSE;
END;

FUNCTION GetNumericInput(prompt : STRING) : INTEGER;
VAR
	output,code:INTEGER;
	ans:STRING;
BEGIN
	WHILE(TRUE) DO
	BEGIN
		writeln(prompt);
		readln(ans);
		IF IsAnInt(ans) THEN
		BEGIN
			Val(ans, output, code);
			RETURN output;
		END
		ELSE
			writeln('Your entry was not a number.');
	END;
END;

FUNCTION GetInput(question : STRING) : STRING;
VAR
	ans:STRING;
BEGIN
	WHILE(TRUE) DO
	BEGIN
		writeln(question);
		readln(ans);
		IF ans = '' THEN
			writeln('Your entry seems empty.')
		ELSE
			RETURN ans;
	END;
END;

FUNCTION AskToPlayAgain : BOOLEAN;
VAR
	ans:STRING;
	i:INTEGER;
BEGIN
	WHILE(TRUE) DO
	BEGIN
		ans := GetInput('Would you like to play again? ("YES" or "NO")');
		FOR i := 1 TO Length(ans) DO
			ans[i] := UpCase(ans[i]);
		IF ans = 'YES' THEN RETURN TRUE;
		IF ans = 'Y' THEN RETURN TRUE;
		IF ans = 'NO' THEN RETURN FALSE;
		IF ans = 'N' THEN RETURN FALSE;
		writeln('Please respond with "YES" or "NO"');
	END;
END;

VAR
	Running,GotMaxNumber,GameOver:BOOLEAN;
	MaxNumber,Answer,Tries,Guess:INTEGER;
	strMaxNumber:STRING;
BEGIN
	Randomize();
	Running := TRUE;
	writeln('*** GUESS A NUMBER : Pascal ***');
	WHILE(Running = TRUE) DO
	BEGIN
		WHILE(GotMaxNumber = FALSE) DO
		BEGIN
			MaxNumber := GetNumericInput('Please enter the maximum number you wish to use');
			IF(MaxNumber > 0) THEN
			BEGIN
				GotMaxNumber := TRUE;
				Answer := Random(MaxNumber) + 1;
				GameOver := FALSE;
				Tries := 0;
				writeln('Ok, I am thinking of a number between 1 and ', MaxNumber, '.');
				LEAVE;
			END
			ELSE
				writeln('The maximum number should be greater than zero');
		END;
		Str(MaxNumber, strMaxNumber);
		Guess:=GetNumericInput('Guess a number between 1 and ' + strMaxNumber + ':');
		Tries := Tries + 1;
		IF(Guess > Answer) THEN
			writeln('Too high.');
		IF(Guess < Answer) THEN
			writeln('Too low');
		IF(Guess = Answer) THEN
		BEGIN
			IF(Tries = 1) THEN
				writeln('You got it in 1 try!')
			ELSE
				writeln('You got it in ', Tries, ' tries!');
			GameOver := TRUE;
		END;
		IF(GameOver) THEN
		BEGIN
			Running := AskToPlayAgain();
			IF(Running) THEN
				GotMaxNumber := FALSE;
		END;
	END;	
	writeln('Thanks for playing!');
	writeln('*** GAME OVER ***');
END.