use strict;
use Tie::File;
use Benchmark::Timer;

our $N ||= 100000;

sub shuffle {
	my $shuffled = ();
	my $numlines = scalar @{$_[0]};
	while ($numlines > 0) {
		my $randomLineNum = int rand $numlines;
		push(@$shuffled, $randomLineNum);
		splice(@{$_[0]}, $randomLineNum, 1);
		$numlines--;
	}
	return $shuffled;
}

open OUT, '>', 'junk.dat' or die $!;
printf OUT "%030d\n", $_ for 0 .. $N;
close OUT;

my @lines;
tie @lines, 'Tie::File', 'junk.dat';
my @indexList = (0..scalar @lines);
my $T = new Benchmark::Timer;

$T->start( "shuffling $N lines" );
my $newOrder = shuffle scalar \@indexList;
$T->stop( "shuffling $N lines" );

$T->start( "Writing New ordered File" );
open NEW, ">sortedJunk.dat";
foreach my $lineNum(@$newOrder){
	print NEW $lines[$lineNum],"\n";
}
$T->stop( "Writing New ordered File" );

$T->report();