#!/usr/bin/perl

$|=1;

use Term::ReadKey;
ReadMode 3;
($w, $h) = GetTerminalSize; #get size of the screen

$x1 = 0; $y1 = 0; #ball start coordinates
$dx = 0.05; $dy = 0.05; #increments to the ball coordinates

$x = 0; #start position of the pad

while (1) {

$key = ReadKey -1;

if ($key eq "d") {$x++; $x = $w-10 if $x > $w-10} #moving the pad to the right
if ($key eq "a") {$x--; $x = 0     if $x < 0} #moving the pad to the left

print "\e[H"; print "\n" x ($h-2); print "\r\e[K"; print " " x $x; print "##########\r\e[H"; #drawing the pad at the bottom of the screen

for (0..($h-3)) {print " " x ($w); print "\n"} #cleaning the screen above the pad
print "\e[H\n\n\n"; print "\n" x $y1; print " " x $x1; print "O\r"; #drawing the ball

$x1 += $dx; #update coordinates of the ball
$y1 += $dy;

$dx *= -1 if $x1 >= $w-1 || $x1 <= 0; #if the ball hits the left or right wall
$dy *= -1 if $y1 <= 0 || ( $y1 >= $h-5 && $x1 > $x && $x1 < $x+10 ); #if the ball hits the top wall or the pad

if ($y1 > $h-4) {ReadMode 0; die "\nyou lose!\n"} #if the ball doesn't hit the pad

}

ReadMode 0;