use v5.14;

package TheGame
{
    use Moo;
    use POSIX qw(floor ceil);
    
    has in              => (is => 'ro', default => sub { \*STDIN });
    has out             => (is => 'ro', default => sub { \*STDOUT });
    has lower_bound     => (is => 'rw');
    has upper_bound     => (is => 'rw');
    has guess_count     => (is => 'rw', default => sub { 0 });
    has guess_technique => (is => 'ro', default => sub { 'random' });
    
    sub play
    {
        my $self = shift->new(@_);
        
        printf {$self->out} (
            "Choose a number between %d and %d!\n",
            $self->lower_bound,
            $self->upper_bound,
        );
        sleep(2);
        
        GUESS: {
            my $guess = $self->make_guess;
            my $wrong = $self->analyse_guess($guess);

            if ($wrong and $self->upper_bound <= $self->lower_bound) {
                die "stop cheating!";
            }

            if ($wrong > 0) {  # too high
                $self->upper_bound($guess - 1);
                redo GUESS;
            }
            
            if ($wrong < 0) {  # too low
                $self->lower_bound($guess + 1);
                redo GUESS;
            }
        }
        
        printf {$self->out} (
            "Got it in %d guesses!\n",
            $self->guess_count,
        );
    }
    
    sub make_guess
    {
        my $self = shift;
        state $toggle = 0;
        
        my $guess;
        if ($self->guess_technique =~ /good/)
        {
            my $diff = $self->upper_bound - $self->lower_bound;
            $guess = floor(
                +    ($self->upper_bound / 2)
                +    ($self->lower_bound / 2)
                +    ($diff / 10)
                -rand($diff / 5)
            );
        }
        elsif ($self->guess_technique =~ /halves/)
        {
            $guess = floor(
                +    ($self->upper_bound / 2)
                +    ($self->lower_bound / 2)
            );
        }
        elsif ($self->guess_technique =~ /thirds/)
        {
            my $upper_or_lower = (++$toggle % 2)
                ? $self->upper_bound
                : $self->lower_bound;
            $guess = floor(
                +    ($self->upper_bound / 3)
                +    ($self->lower_bound / 3)
                +    ($upper_or_lower / 3)
            );
        }
        else  # random number in the range
        {
            $guess = floor(
                +    $self->lower_bound
                +    rand($self->upper_bound - $self->lower_bound)
            );
        }
        
        $guess++ while $guess < $self->lower_bound;
        $guess-- while $guess > $self->upper_bound;
        
        $self->guess_count( $self->guess_count + 1 );
        
        return $guess;
    }
    
    sub analyse_guess
    {
        my ($self, $guess) = @_;

        printf {$self->out} (
            "My guess is %d. Am I 'too high', 'too low' or 'right'?  "
+,
            $guess,
        );

        ANSWER: {
            my $in     = $self->in;
            my $answer = <$in>;
            
            return  0 if $answer =~ m{ (right) | (correct) }x;
            return  1 if $answer =~ m{ (too \s* high) | (lower) }x;
            return -1 if $answer =~ m{ (too \s* low) | (higher) }x;
            
            print {$self->out} "Sorry... what was that?  ";
            redo ANSWER;
        }
    }
}

TheGame->play(lower_bound => 1, upper_bound => 1000, guess_technique =
+> 'good');
[download]

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