use strict;
use warnings;
use 5.010;

use Benchmark qw(:all);

my @dir_skip = ( '$RECYCLE.BIN', 'System Volume Information', 'Config.Msi' );
my $dir_skip = join '|', map { quotemeta } @dir_skip;
my $dir_skip_regexp = qr {$dir_skip\$};

sub FS_sweep {
    my $start_nod_arr_ref = shift;
    my $sub_ref           = shift;    # callback

    my @to_do = @$start_nod_arr_ref;
    my $cnt   = 0;
    my $t0    = Benchmark->new;

    my $sub_log = sub {
        warn '!! ', shift, "\n", ' ' x 12, "cnt: $cnt\n";
    };

    while ( my $nod = shift @to_do ) {
        if (1) { $sub_log->($nod) if not $cnt % 10000; }
        $cnt++;

        my $f_rv = -f $nod;
        if ( !defined $f_rv ) {
            $sub_log->("ERROR <$nod> No such file or directory $!");
            next;
        }
        if ($f_rv) {
            my @rv;

            # using the special filehandle consisting of a solitary underline
            if ( not( @rv = stat( (_) ) ) ) {
                $sub_log->("ERROR Can't stat <$nod> $!");
            }
            else {
                my $stat_ref = \@rv;
                $sub_ref->( $nod, $stat_ref );    # call callback
            }
        }
        elsif ( -d (_) ) {
            if ( $nod =~ m{$dir_skip_regexp} ) {
                $sub_log->("SKIPING DIR $nod");
                next;
            }
            my @nod = (
                grep { !m{[/][.][.]?$} } glob( '"' . $nod . '/.*"' ),
                glob( '"' . $nod . '/*"' )
            );
            unshift @to_do, @nod;
        }
        else { $sub_log->("ERROR? $nod"); }
    }
    if (1) {
        my $td = timediff( Benchmark->new, $t0 );
        my $node_per_second = $td->cpu_p > 0 ? $cnt / $td->cpu_p : -1;
        warn sprintf "\n!! FS_sweep DONE nodes: %d  1/s: %d\n",
          $cnt, $node_per_second;
    }
}

my @output;

sub FS_file_path {
    my $file_path    = shift;
    my $stat_arr_ref = shift;
    push @output, "$file_path";
}

sub FS_file_big {
    my $file_path    = shift;
    my $stat_arr_ref = shift;
    my $size         = $stat_arr_ref->[7];
    push @output, "BIG $file_path size: $size\n" if $size > 100000000;
}

warn "\n!! FS_file_path START";
FS_sweep( ['C:\Program Files\WindowsPowerShell'], \&FS_file_path );
warn "\n!! FS_file_path:\n", join "\n", @output[ 0 .. 10 ];
@output = ();

warn "\n!! FS_file_big START";
foreach my $dev (qw{ C D P Q R S }) {
    my $t0 = Benchmark->new;
    FS_sweep( ["$dev:"], \&FS_file_big );
    my $td = timediff( Benchmark->new, $t0 );
    warn sprintf "!!     Device %s:  %s \n\n", $dev, timestr($td);
}
warn "\n!! FS_file_big:\n", join "\n", @output;
@output = ();