my $CACHE_DIR = '/tmp/xmlcache';
use File::Path qw/make_path/;
make_path($CACHE_DIR, {verbose=>1});

use URI;
use HTTP::Tiny;
use Text::CleanFragment qw/clean_fragment/;
use File::Spec::Functions qw/catfile/;
my $http = HTTP::Tiny->new;
XML::LibXML::externalEntityLoader(sub {
	my ($url, $id) = @_;
	die "Can't handle ID '$id'" if length $id;
	my $uri = URI->new($url);
	my $file;
	if (!$uri->scheme) { $file = $url }
	elsif ($uri->scheme eq 'file') { $file = $uri->path }
	elsif ($uri->scheme=~/\Ahttps?\z/i) {
		# Note there is a (tiny) chance of filename collisions here!
		$file = catfile($CACHE_DIR, clean_fragment("$uri"));
		if (!-e $file) {
			warn "'$uri' => Mirroring to '$file'...\n"; #Debug
			my $resp = $http->mirror($uri, "$file");
			die "$uri: $resp->{status} $resp->{reason}\n"
				unless $resp->{success};
		}
	}
	else { die "Can't handle URL scheme: ".$uri->scheme }
	warn "'$uri' => Loading '$file' from disk\n"; #Debug
	open my $fh, '<', $file or die "$file: $!";
	my $data = do { local $/; <$fh> };
	close $fh;
	return $data;
});