package SL::DB::Helper::PriceTaxCalculator;

use strict;

use parent qw(Exporter);
our @EXPORT = qw(calculate_prices_and_taxes);

use Carp;
use List::Util qw(sum);
use SL::DB::PriceFactor;
use SL::DB::Unit;

sub calculate_prices_and_taxes {
  my ($self) = @_;

  my $is_sales            = $self->can('customer') && $self->customer;

  my %units_by_name       = map { ( $_->name => $_ ) } @{ SL::DB::Manager::Unit->get_all        };
  my %price_factors_by_id = map { ( $_->id   => $_ ) } @{ SL::DB::Manager::PriceFactor->get_all };
  my %taxes_by_chart_id   = ();

  $self->netamount(  0);
  $self->marge_total(0);
  my $lastcost_total = 0;

  my $idx = 0;

  foreach my $item ($self->items) {
    $idx++;

    my $part_unit  = $units_by_name{ $item->part->unit };
    my $item_unit  = $units_by_name{ $item->unit       };

    croak("Undefined unit " . $item->part->unit) if !$part_unit;
    croak("Undefined unit " . $item->unit)       if !$item_unit;

    $item->base_qty($item_unit->convert_to($item->qty, $part_unit));

    my $num_dec   = num_decimal_places($item->sellprice);
    my $discount  = round($item->sellprice * ($item->discount || 0), $num_dec);
    my $sellprice = round($item->sellprice - $discount,              $num_dec);

    $item->price_factor(      ! $item->price_factor_obj   ? 1 : ($item->price_factor_obj->factor   || 1));
    $item->marge_price_factor(! $item->part->price_factor ? 1 : ($item->part->price_factor->factor || 1));
    my $linetotal = round($sellprice * $item->qty / $item->price_factor, 2);

    if (!$linetotal) {
      $item->marge_total(  0);
      $item->marge_percent(0);

    } else {
      my $lastcost = ! ($item->lastcost * 1) ? ($item->part->lastcost || 0) : $item->lastcost;

      $item->marge_total(  $linetotal - $lastcost / $item->marge_price_factor);
      $item->marge_percent($item->marge_total * 100 / $linetotal);

      $self->marge_total(  $self->marge_total + $item->marge_total);
      $lastcost_total += $lastcost;
    }

    my $taxkey     = $item->part->get_taxkey(date => $self->transdate, is_sales => $is_sales, taxzone => $self->taxzone_id);
    my $tax_rate   = $taxkey->tax->rate;
    my $tax_amount = undef;

    if ($self->taxincluded) {
      $tax_amount = $linetotal * $tax_rate / ($tax_rate + 1);
      $sellprice  = $sellprice             / ($tax_rate + 1);

    } else {
      $tax_amount = $linetotal * $tax_rate;
    }

    $taxes_by_chart_id{ $taxkey->chart_id } ||= 0;
    $taxes_by_chart_id{ $taxkey->chart_id }  += $tax_amount;

    $self->netamount($self->netamount + $sellprice * $item->qty / $item->price_factor);

    $::lxdebug->message(0, "CALCULATE! ${idx} i.qty " . $item->qty . " i.sellprice " . $item->sellprice . " sellprice $sellprice taxamount $tax_amount " .
                        "i.linetotal $linetotal netamount " . $self->netamount . " marge_total " . $item->marge_total . " marge_percent " . $item->marge_percent);
  }

  my $tax_sum = sum map { round($_, 2) } values %taxes_by_chart_id;

  $self->amount(       round($self->netamount + $tax_sum, 2));
  $self->netamount(    round($self->netamount,            2));
  $self->marge_percent($self->netamount ? ($self->netamount - $lastcost_total) * 100 / $self->netamount : 0);

  return $self unless wantarray;
  return ( self  => $self,
           taxes => \%taxes_by_chart_id,
         );
}

sub round {
  return $::form->round_amount(@_);
}

sub num_decimal_places {
  return length( (split(/\./, '' . shift, 2))[1] || '' );
}

1;
__END__

=pod

=encoding utf8

=head1 NAME

SL::DB::Helper::PriceTaxCalculator - Mixin for calculating the prices,
amounts and taxes of orders, quotations, invoices

=head1 FUNCTIONS

=over 4

=item C<calculate_prices_and_taxes %params>

Calculates the prices, amounts and taxes for an order, a quotation or
an invoice. The function assumes that the mixing package has a certain
layout and provides certain functions:

=over 2

=item C<transdate>

The record's date.

=item C<customer> or C<vendor>

Determines if the record is a sales or purchase record.

=item C<items>

Accessor returning all line items for this record. The line items
themselves must again have a certain layout. Instances of
L<SL::DB::OrderItem> and L<SL::DB::InvoiceItem> are supported.

=back

The following values are calculated and set for C<$self>: C<amount>,
C<netamount>, C<marge_percent>, C<marge_total>.

The following values are calculated and set for each line item:
C<base_qty>, C<price_factor>, C<marge_price_factor>, C<marge_total>,
C<marge_percent>.

The objects are not saved.

Returns C<$self> in scalar context.

In array context a hash with the following keys is returned:

=over 2

=item C<self>

The object itself.

=item C<taxes>

A hash reference with the calculated taxes. The keys are chart IDs,
the values the calculated taxes.

=back

=back

=head1 BUGS

Nothing here yet.

=head1 AUTHOR

Moritz Bunkus E<lt>m.bunkus@linet-services.deE<gt>

=cut