use strict;
use List::Util 'sum';

local $\ = "\n";
local $, = "\n";

my $STRUCTURE;
my @FEEDS = sort { $a <=> $b } keys %{{map { map { $_ => 1 } map { keys %{$_->{'feeds'}} } values %$_ } @$STRUCTURE}};

print
    map {
        my $d=$_;

        map {
            my $a=$_;

            T('stat', {'date' => $d},
                T('feeds', undef,
                    map {
                        my $f=$_;
                        T('feed', {'id' => $f},
                            map { my $t=$_; T($t, undef, sum map { $_->{$t} } map { $_->{$f} } map { $_->{'feeds'} } @$a) } 'request', 'click', 'error'
                        )
                    } @FEEDS
                ),

                T('total', undef,
                    map { my $t=$_; T($t, undef, sum map { $_->{$t} } map { $_->{'total'} } @$a) } 'request', 'click'
                ),
            )
        } [
            map { $_->{$d} || () } @$STRUCTURE
        ]
    }
    sort keys %{{map { map { $_ => 1 } keys %$_ } @$STRUCTURE}};

sub T {
    my ($name, $attr) = (shift, shift);
    map { @_ ? ("<$_>", @_, "") : "<$_/>" }
    join ' ', $name, map { qq{$_="$attr->{$_}"} } keys %$attr;
}