path: root/LedgerSMB/Tax.pm

#=====================================================================
#
# Tax support module for LedgerSMB
# LedgerSMB::Tax
#  Default simple tax application
#
# LedgerSMB 
# Small Medium Business Accounting software
# http://www.ledgersmb.org/
# 
#
# Copyright (C) 2006
# This work contains copyrighted information from a number of sources all used
# with permission.  It is released under the GNU General Public License 
# Version 2 or, at your option, any later version.  See COPYRIGHT file for 
# details.
#
#
#======================================================================
# This package contains tax related functions:
#
# apply_taxes - applies taxes to the given subtotal
# extract_taxes - extracts taxes from the given total
# initialize_taxes - loads taxes from the database
# calculate_taxes - calculates taxes
#
#====================================================================
package Tax;

use Math::BigFloat;

sub init_taxes {
    my ($form, $taxaccounts) = @_;
    my $dbh = $form->{dbh};
    @taxes = ();
    my @accounts = split / /, $taxaccounts;
    my $query = qq|SELECT t.taxnumber, c.description,
            t.rate, t.chart_id, t.pass, m.taxmodulename
            FROM tax t INNER JOIN chart c ON (t.chart_id = c.id)
            INNER JOIN taxmodule m ON (t.taxmodule_id = m.taxmodule_id)
            WHERE c.accno = ?|;
    my $sth = $dbh->prepare($query);
    foreach $taxaccount (@accounts) {
        $sth->execute($taxaccount) || $form->dberror($query);
        my $ref = $sth->fetchrow_hashref;

        my $module = $ref->{'taxmodulename'};
        require "LedgerSMB/Taxes/${module}.pm";
        $module =~ s/\//::/g;
        my $tax = (eval 'Taxes::'.$module)->new();

        $tax->pass($ref->{'pass'});
        $tax->account($taxaccount);
        $tax->rate(Math::BigFloat->new($ref->{'rate'}));
        $tax->taxnumber($ref->{'taxnumber'});
        $tax->chart($ref->{'chart'});
        $tax->description($ref->{'description'});
        $tax->value(Math::BigFloat->bzero());

        push @taxes, $tax;
        $sth->finish;
    }
    return @taxes;
}

sub calculate_taxes {
    my ($taxes, $form, $subtotal, $extract) = @_;
    my $total = Math::BigFloat->bzero();
    my %passes;
    foreach my $tax (@taxes) {
        push @{$passes{$tax->pass}}, $tax;
    }
    my @passkeys = sort keys %passes;
    @passkeys = reverse @passkeys if $extract;
    foreach my $pass (@passkeys) {
        my $passrate = Math::BigFloat->bzero();
        my $passtotal = Math::BigFloat->bzero();
        foreach my $tax (@{$passes{$pass}}) {
            $passrate += $tax->rate;
        }
        foreach my $tax (@{$passes{$pass}}) {
            $passtotal += $tax->apply_tax($form, $subtotal + $total) if not $extract;
            $passtotal += $tax->extract_tax($form, $subtotal - $total, $passrate) if $extract;
        }
        $total += $passtotal;
    }
    return $total;
}

sub apply_taxes {
    my ($taxes, $form, $subtotal) = @_;
    return $subtotal + calculate_taxes($taxes, $form, $subtotal, 0);
}

sub extract_taxes {
    my ($taxes, $form, $subtotal) = @_;
    return $subtotal - calculate_taxes($taxes, $form, $subtotal, 1);
}

1;