use strict;
use IO::File;

my %du1; recursetree(\%du1, readdu(shift), "");
my %du2; recursetree(\%du2, readdu(shift), "");

my $changed= diffdu(\%du1, \%du2);

# du1 now contains the entries only in du1, etc.

print "only in first\n";
my $n=0;
for my $d (sort {$du1{$b} <=> $du1{$a} } keys %du1) {
    printf("<%8d %s\n", $du1{$d}, $d);
    last if $n++ ==10 && $du1{$d}<10000;
}
print "only in second\n";
$n=0;
for my $d (sort {$du2{$b} <=> $du2{$a} } keys %du2) {
    printf(">%8d %s\n", $du2{$d}, $d);
    last if $n++ ==10 && $du2{$d}<10000;
}
print "changes\n";
my @changeddirs= sort {$changed->{$b} <=> $changed->{$a}} keys %$changed;
my $di=1 ;
while ($di<=10 && $changed->{$di}<10000) {
    my $d= $changeddirs[$di++];
    printf("%s%8d %s\n", ($changed->{$d}<0)?("-", -$changed->{$d}):("+", $changed->{$d}), $d);
}
my $di=-2;
while ($di>=-11 && $changed->{$di}>-10000) {
    my $d= $changeddirs[$di--];
    printf("%s%8d %s\n", ($changed->{$d}<0)?("-", -$changed->{$d}):("+", $changed->{$d}), $d);
}

sub readdu {
    my $fn=shift;
    my $fh= IO::File->new($fn, "r") or die "$fn: $!\n";
    my $root= { subdirs=>{}, dutotal=>0, subtotal=>0, };
    while (<$fh>) {
        if (/(\d+)\s+(.*?)\s*$/) {
            my ($total, $path)= ($1, $2);
            my @path= split /\//, $path;
            my $p= $root;
            my $q= undef;
            for my $dir (@path) {
                if (!exists $p->{subdirs}{$dir}) {
                    $p->{subdirs}{$dir}= {
                        subdirs=>{},
                        dutotal=>0,
                        subtotal=>0,
                    };
                }
                ($p,$q)= ($p->{subdirs}{$dir}, $p);
            }
            $p->{dutotal}= $total;
            $q->{subtotal}+=$total if ($q);

        }
    }
    $fh->close();
    return $root;
}
sub recursetree {
	my ($du, $dir, $path)= @_;
        $du->{$path}= ($dir->{dutotal}-$dir->{subtotal})/2;
        #$dir->{dutotal}/2

	recursetree($du, $dir->{subdirs}{$_}, $path.'/'.$_) for keys %{$dir->{subdirs}};
}
sub diffdu {
    my ($du1, $du2)= @_;
    my %changed;
    for my $d (keys %$du1) {
        if (exists $du2->{$d}) {
            my $diff= $du2->{$d}-$du1->{$d};
            delete $du2->{$d};
            delete $du1->{$d};
            $changed{$d}= $diff if ($diff);
        }
    }
    return \%changed;
}