#!/usr/bin/perl
use strict;
use warnings;
use XML::Twig;

my $xmlParser = XML::Twig->new();

# Fetch the new books to add to the catalog
my $new_items = fetch_xml('new_items.xml');
my @add;
for my $book ($new_items->root->children('book')) {
    push @add, $book->copy();
}
print scalar(@add), " new books to add to the catalog!\n";

# Add the books to the catalog
my $cur_catalog = fetch_xml('current_catalog.xml');
for my $book (@add) {
    # Each book will be added after the last book in the catalog
    $book->paste(last_child => $cur_catalog->root);
}

# Now dump our current catalog
$cur_catalog->flush( \*STDERR, pretty_print=>'indented' );

sub fetch_xml {
    my $fname = shift;
    my $txt = do {
        open my $FH, '<', $fname or die "$fname: $!";
        local $/;
        <$FH>;
    };
    $xmlParser->parse($txt);
    return $xmlParser;
}