use warnings;
use strict;
use XML::Rules;
use Text::CSV;

my $parser = XML::Rules->new(
	stripspaces => 3|4,
	rules => [ 'products|downloads|group|group_items' => 'pass',
		product => 'by sku', 'sku|name|url' => 'content',
		item => sub { $_[1]->{name} => $_[1]->{url} },
		_default => sub { die "Unknown tag $_[0]" } ],
);
my $itms = $parser->parse_file('example.xml');

my @columns = sort keys %{{map {$_=>1} map {keys %$_} values %$itms}};

my $csv = Text::CSV->new({binary=>1, auto_diag=>2, eol=>$/,
	always_quote=>1 });
$csv->print(select, ["sku", @columns]);
for my $sku (sort keys %$itms) {
	$csv->print(select, [$sku, map { $itms->{$sku}{$_} } @columns ]);
}