+sub last_used_ar_chart {
+ my ($self) = @_;
+
+ my $query = <<EOSQL;
+ SELECT c.id
+ FROM chart c
+ JOIN acc_trans ac ON (ac.chart_id = c.id)
+ JOIN ar a ON (a.id = ac.trans_id)
+ WHERE (a.customer_id = ?)
+ AND (c.category = 'I')
+ AND (c.link !~ '_(paid|tax)')
+ AND (a.id IN (SELECT max(a2.id) FROM ar a2 WHERE a2.customer_id = ?))
+ ORDER BY ac.acc_trans_id ASC
+ LIMIT 1
+EOSQL
+
+ my ($chart_id) = SL::DBUtils::selectfirst_array_query($::form, $self->db->dbh, $query, ($self->id) x 2);
+
+ return if !$chart_id;
+ return SL::DB::Chart->load_cached($chart_id);
+}
+
+sub is_customer { 1 };
+sub is_vendor { 0 };
+sub payment_terms { goto &payment }
+sub number { goto &customernumber }
+
+sub create_zugferd_invoices_for_this_customer {
+ my ($self) = @_;
+
+ no warnings 'once';
+ return $::instance_conf->get_create_zugferd_invoices if $self->create_zugferd_invoices == -1;
+ return $self->create_zugferd_invoices;
+}
+
+sub default_billing_address {
+ my $self = shift;
+
+ die 'not an accessor' if @_ > 1;
+ return first { $_->default_address } @{ $self->additional_billing_addresses };
+}
+