use POSIX       qw( strftime       );
use Time::Local qw( timegm_nocheck );

my ($day, $mon, $year, $wday)
   = (localtime())[3..6];  # Defaults to now.

$year += 1900;
$day  += (7 - $wday + 4) % 7;

$next_th = timegm_nocheck(0,0,0,$day,$mon,$year);

print(strftime('%Y-%m-%d', gmtime($next_th)), "\n");