sub calculate_invoice_dates {
my ($self, %params) = @_;
sub calculate_invoice_dates {
my ($self, %params) = @_;
$start_date = max($start_date, $params{start_date}) if $params{start_date};
$end_date = min($end_date, $params{end_date}) if $params{end_date};
my @dates;
$start_date = max($start_date, $params{start_date}) if $params{start_date};
$end_date = min($end_date, $params{end_date}) if $params{end_date};
my @dates;
push @dates, $cur_date->clone if $cur_date > $start_date;
$cur_date->add(months => $period_len);
push @dates, $cur_date->clone if $cur_date > $start_date;
$cur_date->add(months => $period_len);