First round of tax code replacement, adds cumulative tax support

git-svn-id: https://ledger-smb.svn.sourceforge.net/svnroot/ledger-smb/trunk@195 4979c152-3d1c-0410-bac9-87ea11338e46

1 files changed, 100 insertions, 0 deletions

diff --git a/LedgerSMB/Tax.pm b/LedgerSMB/Tax.pm
new file mode 100755
index 00000000..4c7bd121
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+++ b/LedgerSMB/Tax.pm
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+#=====================================================================
+#
+# 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) {
+		$sth->execute(int($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;