#! /usr/bin/perl 
 
use CGI::Carp qw(fatalsToBrowser warningsToBrowser); 
use POSIX qw(ceil); 
 
use strict; 
use warnings; 
 
print "Content-Type: text/plain\n\n"; 
warningsToBrowser(1); 
 
########################################################### 
 
my $weight = 800; 
 
my %postage = Postage($weight); 
 
while (my ($location, $cost_ref) = each %postage) { 
	print "$location\n"; 
	print "\t@$_\n" for @$cost_ref; 
} 
 
########################################################### 
 
our %POSTAGE; 
INIT { 
	local $/ = "\n\n"; # Paragraph mode 
	 
	while (<DATA>) { 
		chomp; 
 
		# Comments begin with # 
		my ($service, @rates) = grep {!/^#/} split "\n"; 
		 
		# Eval rates 
		for (@rates) { 
			$_ = [split "\t"]; 
			$_->[1] = eval $_->[1]; 
			die "$service - $@" if $@; 
		} 
		 
		$POSTAGE{$service} = \@rates; 
	} 
} 
 
sub Postage { 
	my $weight = shift; 
	die "Invalid weight" unless $weight < 1_000_000_000; 
 
	my %postage; 
 
	for my $service (sort keys %POSTAGE) { 
		# The Last Max 
		my $max = $POSTAGE{$service}[-1][0]; 
		 
		# Subdivide Package according to max weight 
		my @weights = $weight; 
		while ($max && $weights[-1] > $max) { 
			unshift @weights, $max; 
			$weights[-1] -= $max; 
		} 
		 
		for my $w (@weights) { 
			for my $rate (@{$POSTAGE{$service}}) { 
				next if $rate->[0] && $w > $rate->[0]; 
				push @{$postage{$service}}, [$w, sprintf "%.2f", $rate->[1]($w)]; 
				last; 
			} 
		} 
	} 
	 
	return %postage; 
} 
 
########################################################### 
 
# Each section is __DATA__ is labelled by a destination 
# and then by max weight and the sub that determines the cost. 
# If no max weight is specified, then treat as infinate. 
 
__DATA__ 
UK & Europe 
	sub { 0.00 } 
 
USA 
200	sub { 2.00 } 
	sub { my $w = shift; 2.00 + 1.00 * ceil(($w-200)/100) } 
 
Australia & New Zealand 
200	sub { 2.00 } 
2200	sub { my $w = shift; 2.00 * (1 + 1 / 1.1) ** ceil(($w - 200) / 200) } 
 
Other 
200	sub { 2.00 } 
	sub { my $w = shift; 2.00 + 1.00 * ceil(($w - 200) / 200) } 
 
Test 
100	sub { 1.00 } 
200	sub { 1.00 + 0.99 } 
300	sub { 1.00 + 0.99 + 0.80 }