#!/usr/bin/perl
use strict;
use warnings;
use Term::ANSIScreen qw/:color :cursor :screen/;
use Term::ReadKey;

my $rows = 50;

ReadMode('noecho');
cls;
setscroll (1, $rows);
locate 1, 1;

my @screenRows;

# Create the initial screen
push @screenRows, newRow() for 1 .. $rows;
print join "\n", @screenRows, '';

my $wait   = 1;
my $skierx = 40;

while (1) {
    if (defined(my $key = ReadKey(-1))) {
        if ($key eq "j") {
            --$skierx;
        } elsif ($key eq "k") {
            ++$skierx;
        } elsif ($key eq "x") {
            exit;
        }
    }

    # Generate and show a new line    
    shift @screenRows;
    push @screenRows, newRow();
    print $screenRows[-1];
    
    # Collision detection
    if (' ' ne substr $screenRows[$rows / 2], $skierx - 1, 1) {
        locate $rows, 1;
        print "Crash!\n";
        exit;
    }
    
    # Show skier's updated position
    locate $rows / 2, $skierx;
    print "V";

    # wait
    select(undef, undef, undef, $wait);    #pauses here
    $wait -= 0.003;
}


sub newRow {
    my $col = int(rand(80));
    return ' ' x $col . 'T' . (' ' x (78 - $col));
}