--- /dev/null
+package SL::DB::Helper::CustomVariables;
+
+use strict;
+use Carp;
+use Data::Dumper;
+use List::Util qw(first);
+use SL::DB::CustomVariableConfig;
+
+use constant META_CVARS => 'cvars_config';
+
+sub import {
+ my ($class, %params) = @_;
+ my $caller_package = caller;
+
+ # TODO: if module is empty, module overloading needs to take effect
+ # certain stuff may have more than one overload, odr even more than one type
+ defined $caller_package or croak 'need to be included from a caller reference';
+
+ $params{module} ||= _calc_modules_from_overloads(%params) if $params{overloads};
+ $params{sub_module} ||= '';
+ $params{id} ||= 'id';
+
+ $params{module} || $params{sub_module} or croak 'need param module or sub_module';
+
+ save_meta_info($caller_package, %params);
+ make_cvar_accessor($caller_package, %params);
+ make_cvar_alias($caller_package, %params) if $params{cvars_alias};
+ make_cvar_by_configs($caller_package, %params);
+ make_cvar_by_name($caller_package, %params);
+}
+
+sub save_meta_info {
+ my ($caller_package, %params) = @_;
+
+ my $meta = $caller_package->meta;
+ return 0 if $meta->{META_CVARS()};
+
+ $meta->{META_CVARS()} = \%params;
+}
+
+sub make_cvar_accessor {
+ my ($caller_package, %params) = @_;
+
+ my @module_filter = $params{module} ?
+ ("config.module" => $params{module}) :
+ ();
+
+ $caller_package->meta->add_relationships(
+ custom_variables => {
+ type => 'one to many',
+ class => 'SL::DB::CustomVariable',
+ column_map => { ($params{id} || 'id') => 'trans_id' },
+ manager_args => { with_objects => 'config' },
+ query_args => [ sub_module => $params{sub_module}, @module_filter ],
+ }
+ );
+}
+
+sub make_cvar_alias {
+ my ($caller_package) = @_;
+ no strict 'refs';
+ *{ $caller_package . '::cvars' } = sub {
+ goto &{ $caller_package . '::custom_variables' };
+ }
+}
+
+# this is used for templates where you need to list every applicable config
+# auto vivifies non existant cvar objects as necessary.
+sub make_cvar_by_configs {
+ my ($caller_package, %params) = @_;
+
+ no strict 'refs';
+ *{ $caller_package . '::cvars_by_config' } = sub {
+ my ($self) = @_;
+ @_ > 1 and croak "not an accessor";
+
+ my $configs = _all_configs(%params);
+ my $cvars = $self->custom_variables;
+ my %cvars_by_config = map { $_->config_id => $_ } @$cvars;
+
+ my @return = map { $cvars_by_config{$_->id} || _new_cvar($self, %params, config => $_) } @$configs;
+
+ return \@return;
+ }
+}
+
+# this is used for print templates where you need to refer to a variable by name
+# TODO typically these were referred as prefix_'cvar'_name
+sub make_cvar_by_name {
+ my ($caller_package, %params) = @_;
+
+ no strict 'refs';
+ *{ $caller_package . '::cvar_by_name' } = sub {
+ my ($self, $name) = @_;
+
+ my $configs = _all_configs(%params);
+ my $cvars = $self->custom_variables;
+ my $config = first { $_->name eq $name } @$configs;
+
+ croak "unknown cvar name $name" unless $config;
+
+ my $cvar = first { $_->config_id eq $config->id } @$cvars;
+
+ if (!$cvar) {
+ $cvar = _new_cvar($self, %params, config => $config);
+ $self->add_custom_variables($cvar);
+ }
+
+ return $cvar;
+ }
+}
+
+sub _all_configs {
+ my (%params) = @_;
+ $params{module}
+ ? SL::DB::Manager::CustomVariableConfig->get_all(query => [ module => $params{module} ])
+ : SL::DB::Manager::CustomVariableConfig->get_all;
+}
+
+sub _overload_by_module {
+ my ($module, %params) = @_;
+
+ while (my ($fk, $class) = each %{ $params{overloads} }) {
+ return ($fk, $class) if $class->meta->{META_CVARS()}->{module} eq $module;
+ }
+
+ croak "unknown overload, cannot resolve module $module";
+}
+
+sub _new_cvar {
+ my ($self, %params) = @_;
+ my $inherited_value;
+ # check overloading first
+ if ($params{sub_module}) {
+ my ($fk, $class) = _overload_by_module($params{config}->module, %params);
+ my $base_cvar = $class->new(id => $self->$fk)->load->cvar_by_name($params{config}->name);
+ $inherited_value = $base_cvar->value;
+ }
+
+ my $cvar = SL::DB::CustomVariable->new(
+ config => $params{config},
+ trans_id => $self->${ \ $params{id} },
+ sub_module => $params{sub_module},
+ );
+ # value needs config
+ $inherited_value
+ ? $cvar->value($inherited_value)
+ : $cvar->value($params{config}->default_value);
+ return $cvar;
+}
+
+sub _calc_modules_from_overloads {
+ my (%params) = @_;
+ my %modules;
+
+ while (my ($fk, $class) = each %{ $params{overloads} }) {
+ eval "require $class"; # make sure the class is loaded
+ my $module = $class->meta->{META_CVARS()}->{module};
+ next if ref $module;
+ $modules{$module} = 1;
+ }
+
+ return [ keys %modules ];
+}
+
+
+1;
+
+__END__
+
+=encoding utf-8
+
+=head1 NAME
+
+SL::DB::Helper::CustomVariables - Mixin to provide custom variables relations
+
+=head1 SYNOPSIS
+
+ # use in a primary class
+ use SL::DB::Helper::CustomVariables (
+ module => 'IC',
+ cvars_alias => 1,
+ );
+
+ # use overloading in a secondary class
+ use SL::DB::Helper::CustomVariables (
+ sub_module => 'orderitems',
+ cvars_alias => 1,
+ overloads => {
+ parts_id => 'SL::DB::Part',
+ }
+ );
+
+=head1 DESCRIPTION
+
+This module provides methods to deal with named custom variables. Two concepts are understood.
+
+=head2 Primary CVar Classes
+
+Primary classes are those that feature cvars for themselves. Currently those
+are Part, Contact, Customer and Vendor. cvars for these will get saved directly
+for the object.
+
+=head2 Secondary CVar Classes
+
+Secondary classes inherit their cvars from member relationships. This is built
+so that orders can save a copy of the cvars of their parts, customers and the
+like to be immutable later on.
+
+Secondary classes may currently not have cvars of their own.
+
+=head1 INSTALLED METHODS
+
+=over 4
+
+=item C<custom_variables [ CUSTOM_VARIABLES ]>
+
+This is a Rose::DB::Object::Relationship accessor, generated for cvars. Use it
+like any other OneToMany relationship.
+
+=item C<cvars [ CUSTOM_VARIABLES ]>
+
+Alias to C<custom_variables>. Will only be installed if C<cvars_alias> was
+passed to import.
+
+=item C<cvars_by_config>
+
+Thi will return a list of CVars with the following changes over the standard accessor:
+
+=over 4
+
+=item *
+
+The list will be returned in the sorted order of the configs.
+
+=item *
+
+For every config exactly one CVar will be returned.
+
+=item *
+
+If no cvar was found for a config, a new one will be vivified, set to the
+correct config, module etc, and registered into the object.
+
+=item *
+
+Vivified cvars for secondary classes will first try to find their base object
+and use that value. If no such value or cvar is found the default value from
+configs applies.
+
+=back
+
+This is useful if you need to list every possible CVar, like in CRUD masks.
+
+=item C<cvar_by_name NAME [ VALUE ]>
+
+Returns the CVar object for this object which matches the given internal name.
+Useful for print templates. If the requested cvar is not present, it will be
+vivified with the same rules as in C<cvars_by_config>.
+
+=back
+
+=head1 AUTHOR
+
+Sven Schöling E<lt>s.schoeling@linet-services.deE<gt>
+
+=cut