#!/usr/bin/perl

use v5.20;
use strict;
use warnings;

my $Num = Prepare_Num( q'51 824 753 556' );

my $verified = check_calc($Num);

if( $verified == 1){
 say "Valid ABN"
}else{
 say "ABN check has been unsuccessful"
}

sub check_calc{

 my $Numset = shift;
 my $woset = weighting_oset();
 
 --$Numset->[0][0];
 print_oset($Numset);   

 my $sum;
 for my $index( 0 .. 10 ){

 $sum += $Numset->[$index][0] *= $woset->[$index][0]; 

 }

 print_oset($Numset);

 $sum %89 == 0;
 
}

sub Prepare_Num{

my $NumString = shift;
say "arg Num: $NumString";

$NumString =~ s/[^0-9]//g;
say "s Num: $NumString";

my $count = $NumString =~ tr/0-9/0-9/;
say "count: $count";
$count == 11 or die "non-conforming ABN. Please check.";

say "tr Num: $NumString";

my $Numset = [];
while( $NumString =~ m/([0-9])/g ){
  push @$Numset, [$1]; 
}

print_oset( $Numset, 1 );

return( $Numset );

}

sub weighting_oset{

 #my $woset = [[[0],[1]],[10]];
 my $woset = [[10]];
 push @$woset, map { $_ %2 == 1 ? [$_] : () } ( 1..19 );
 print_oset( $woset );
 return $woset;

}


sub print_oset{

 my $Numset = shift;
 say "oset: ",@$Numset if @_; # $_[0] == 1;
 say "oset: \[", map("[@$_],", @$Numset), "\]";

}

##### From OP #######
sub Check_ABN {
	my $number = shift ;
	my $abn_invalid = 0 ;
	my $sum = 0 ;
	$number =~ s/\ //g ;
	unless (length($number) eq 11) {
		$abn_invalid = 1 ;
		return $abn_invalid ;
	}
	
	$sum += (substr($number,0,1)-1)*10 ;
	$sum += substr($number,1,1)*1 ;
	$sum += substr($number,2,1)*3 ;
	$sum += substr($number,3,1)*5 ;
	$sum += substr($number,4,1)*7 ;
	$sum += substr($number,5,1)*9 ;
	$sum += substr($number,6,1)*11 ;
	$sum += substr($number,7,1)*13 ;
	$sum += substr($number,8,1)*15 ;
	$sum += substr($number,9,1)*17 ;
	$sum += substr($number,10,1)*19 ;
	if ($sum % 89 eq 0) {
		return $abn_invalid ;
	} else {
#		$abn_error = 1 ;
		return $abn_invalid ;
	}
	# see https://abr.business.gov.au/Help/AbnFormat
}