Perl: Dice roll "fix" to translate 2-8, 5-8, to 2d4, 1d4+3 - perl

Question

I am trying to do some importing of data that uses different dice roll text. For example you'll have 2-4, 2-12, 5-8, 2-5. I am trying to write a translator that will convert them to proper dice rolls. What I have so far will translate it but I end up with some odd rolls. For example on the 5-8 it comes up with 5d1+3. With other things like 2-8 it will give me a reasonable 2d4. I'm trying to figure out how to make it ALWAYS use "real" dice.
Currently I am using this perl script. You simply pass it the dice string you want to fix and it returns what it thinks is the right roll. My problem is I can't think of how to limit the dice "sides" to only these 2,3,4,6,8,12,20 sides.
# turn 2-7 into 1d6+1 or 2-8 into 2d4
sub fix_DiceRolls {
my($diceRoll) = #_;
use POSIX;
if ($diceRoll =~ /^(\d+)(\-)(\d+)\b/i) {
# 2-5
#Group 1. 0-1 `2`
#Group 2. 1-2 `-`
#Group 3. 2-3 `5`
my($count) = $1;
my($size) = $3;
if ($count == 1) {
$diceRoll = "$1d$3";
} else {
my ($newSize) = $size/$count;
my ($remainder) = $size % $count;
my ($round_remainder) = ceil($remainder);
my ($round_newSize) = floor($newSize);
if ($remainder == 0) {
$diceRoll = $count."d".$newSize;
} else {
$diceRoll = $count."d".$round_newSize."+".$round_remainder;
}
}
}
return $diceRoll;
}

Answer 1

The following might help you. It doesn't know how to do 1d6/2, but it correctly translates 4-19 to 3d6+1 | 5d4-1.
#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
my #valid_dice = (4, 6, 8, 10, 12, 20);
sub fix_dice_roll {
my ($dice_roll) = #_;
my ($from, $to) = split /-/, $dice_roll;
my $range = $to - $from + 1;
my #translations;
for my $dice (#valid_dice) {
if (0 == ($range - 1) % ($dice - 1)) {
my $times = ($range - 1) / ($dice - 1);
my $plus = sprintf '%+d', $to - $times * $dice;
$plus = q() if '+0' eq $plus;
push #translations, [ $dice, $times, $plus ];
}
}
#translations = sort { $a->[1] <=> $b->[1] } #translations;
return map "$_->[1]d$_->[0]$_->[2]", #translations;
}
say join ' | ', fix_dice_roll($_) while <>;