+package SL::DB::Helper::AccountingPeriod;
+
+use strict;
+
+use parent qw(Exporter);
+use SL::DBUtils;
+our @EXPORT = qw(get_balance_starting_date);
+
+use Carp;
+
+sub get_balance_starting_date {
+ my ($self,$asofdate) = @_;
+
+ $asofdate ||= DateTime->today_local;
+
+ unless ( ref $asofdate eq 'DateTime' ) {
+ $asofdate = $::locale->parse_date_to_object($asofdate);
+ };
+
+ my $dbh = $::form->get_standard_dbh;
+
+ my $startdate_method = $::instance_conf->get_balance_startdate_method;
+
+ # We could use the following objects to determine the starting date for
+ # calculating the balance from asofdate (the reference date for the balance):
+ # * start_of_year - 1.1., no deviating fiscal year supported
+ # * closed_to - all transactions since the books were last closed
+ # * last_ob - all transactions since last opening balance transaction (usually 1.1.)
+ # * mindate - all transactions in database
+
+ my $start_of_year = $asofdate->clone();
+ $start_of_year->set_day(1);
+ $start_of_year->set_month(1);
+
+ # closedto assumes that we only close the books at the end of a fiscal year,
+ # never during the fiscal year. If this assumption is valid closedto should
+ # also work for deviating fiscal years. But as the trial balance (SuSa)
+ # doesn't yet deal with deviating fiscal years, and it is useful to also close
+ # the books after a month has been exported via DATEV, this method of
+ # determining the starting date isn't recommended and is not the default.
+
+ my $closedto = $::instance_conf->get_closedto;
+ if ($closedto) {
+ $closedto = $::locale->parse_date_to_object($closedto);
+ $closedto->subtract(years => 1) while ($asofdate - $closedto)->is_negative;
+ $closedto->add(days => 1);
+ };
+
+ my ($query, $startdate, $last_ob, $mindate);
+ $query = qq|select max(transdate) from acc_trans where ob_transaction is true and transdate <= ?|;
+ ($last_ob) = selectrow_query($::form, $dbh, $query, $::locale->format_date(\%::myconfig, $asofdate));
+ $last_ob = $::locale->parse_date_to_object($last_ob) if $last_ob;
+
+ $query = qq|select min(transdate) from acc_trans|;
+ ($mindate) = selectrow_query($::form, $dbh, $query);
+ $mindate = $::locale->parse_date_to_object($mindate);
+
+ # the default method is to use all transactions ($mindate)
+
+ if ( $startdate_method eq 'closed_to' and $closedto ) {
+ # if no closedto is configured use default
+ return $::locale->format_date(\%::myconfig, $closedto);
+
+ } elsif ( $startdate_method eq 'start_of_year' ) {
+
+ return $::locale->format_date(\%::myconfig, $start_of_year);
+
+ } elsif ( $startdate_method eq 'all_transactions' ) {
+
+ return $::locale->format_date(\%::myconfig, $mindate);
+
+ } elsif ( $startdate_method eq 'last_ob_or_all_transactions' and $last_ob ) {
+ # use default if there are no ob transactions
+
+ return $::locale->format_date(\%::myconfig, $last_ob);
+
+ } elsif ( $startdate_method eq 'last_ob_or_start_of_year' ) {
+
+ if ( $last_ob ) {
+ return $::locale->format_date(\%::myconfig, $last_ob);
+ } else {
+ return $::locale->format_date(\%::myconfig, $start_of_year);
+ };
+
+ } else {
+ # default action, also used for closedto and last_ob_or_all_transactions if
+ # there are no valid dates
+
+ return $::locale->format_date(\%::myconfig, $mindate);
+ };
+
+};
+
+1;
+__END__
+
+=pod
+
+=encoding utf8
+
+=head1 NAME
+
+SL::DB::Helper::AccountingPeriod - Helper functions for calculating dates relative to the financial year
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item C<get_balance_starting_date $date>
+
+Given a date this method calculates and returns the starting date of the
+financial period relative to that date, according to the configured
+balance_startdate_method in the client configuration. The returned date is
+locale-formatted and can be used for SQL queries.
+
+If $date isn't a DateTime object a date string is assumed, which then gets
+date-parsed.
+
+If no argument is passed the current day is assumed as default.
+
+=back
+
+=head1 BUGS
+
+Nothing here yet.
+
+=head1 AUTHOR
+
+G. Richardson E<lt>information@kivitendo-premium.deE<gt>
+
+=cut