#! /usr/bin/perl

use strict;
use warnings;
use CGI;

my @sizes = (0,500,750,1200);
my @prices = (10,9.5,8.75);
my $per_units = 50;
my $total = '0.00';

my $q = CGI->new();
print $q->header;
print $q->start_html(-style => 'this.css');


if ($q->param('feet') and $q->param('feet') =~ /^\d+$/) {
  if ($q->param('feet') > $sizes[$#sizes]) {
    query_us();
  }
  else {
    calc_total($q->param('feet'));
    total_form($q->param('feet'));
  }
}
else {
  if ($q->param('feet') and $q->param('feet') =~ /^\d+\.\d+$/) {
    calc_total(int $q->param('feet'));
    total_form(int $q->param('feet'));
  }
  else {
    total_form();
  }
}

print $q->end_html;

sub calc_total {
  my ($feet) = @_;
  for my $i (0..$#sizes-1) {
    if ($feet > $sizes[$i] and $feet <= $sizes[$i+1]) {
      $total = ($feet / $per_units) * $prices[$i];
    }
  }
}

sub total_form {
  my ($feet) = @_;
  $feet = 0 if !$feet;
  print $q->start_form;
  print '<table border="0" cellspacing="0" cellpadding="0"><tr>',
    '<th class="headers" rowspan="2">Total Amount Of Footage</th>',
    '<th> <span class="feet">ft</span></th>',
    '<th><span class="total_title">Total Cost</span></th>',
    '</tr><tr>',
    '<td><input type="text" name="feet" value="'.$feet.'">',
    '<input type="submit" name="submit" class="submit" value="" />',
    '</td>',
    '<td id="total_cost">£'.$total.'</td>',
    '</tr><tr class="other">',
    '<th>extra copies</th>',
    '<td colspan="2">£10 each</td>',
    '</tr><tr class="other">',
    '<th>minimum charge</th>',
    '<td colspan="2">£50</td>',
    '</tr></table>';

  print $q->end_form;
}

sub query_us {
  print "over 1200";
}