projekt kivitendo

use List::Util qw(max min);

sub calculate_invoice_dates {

  my ($self, %params) = @_;

  my $cur_date   = $self->first_billing_date        || $self->start_date;

  my $start_date = $self->get_previous_invoice_date || DateTime->new(year => 1970, month => 1, day => 1);

  my $end_date   = $self->end_date                  || DateTime->today_local->add(years => 10);

  my $period_len = $self->get_period_length;

  $start_date    = max($start_date, $params{start_date}) if $params{start_date};

  $end_date      = min($end_date,   $params{end_date})   if $params{end_date};

  my @dates;

  while ($cur_date < $end_date) {

    push @dates, $cur_date->clone if $cur_date > $start_date;

    $cur_date->add(months => $period_len);

  }

  return @dates;

}