#!/usr/bin/perl

my $theight = shift || 25;
my $twidth  = shift || 80;

my @lm = ( ' o ', '/ \\' );

my $play = 'y';

while( $play =~ /y/i )
{
   my $x  = 20;
   my $y  = 5;
   my $dx = 0;
   my $dy = -0.01;

   # forever!
   {
      &draw( $x, $dx, $y, $dy );

      $dy += 0.005;
      $dx *= 0.98;

      $x += $dx unless $x > $twidth - 5;
      $y += $dy;

      $dy = -0.1 if $dy < -0.1;
      $y  = 1 if $y < 1;

      $pids = `ps -e`;

      $dx -= 0.05 if  $pids =~ /\bh\b/;
      $dx += 0.05 if  $pids =~ /\bl\b/;
      $dy -= 0.05 if  $pids =~ /\bk\b/;

      redo unless $theight - $y < 4;
   }

   print "\nVelocity: ", $dy * 100, " m/s\n";

   if ( $dy > 0.1 )
   {
      print "I'm sorry, you have crashed!\n";
   }
   else
   {
      print "Congratulations, you are an ace Lunar pilot!\n";
   }

   print "Play Again?";
   $play = <STDIN>;
}

sub draw
{
   my ($x, $dx, $y, $dy ) = @_;

   `clear`;
   print "x: ", int($x*100),
        " dx: ", int($dx*100),
        "  y: ", int(($theight-$y-4)*100),
        " m dy: ", int($dy*100),
        " m/s\n";

   if ( $y > 1 )
   {
      print "\n" x $y;
      print " "  x $x;
      print $lm[0], "\n";
      print " "  x $x;
      print $lm[1];
      print "\n" x ($theight - $y - 2);
   }
   else
   {
      print "\n" x ($theight-2);
   }
}