#! perl -slw
use strict;

package GenURLs; #! Generals:)
use Carp;
use Data::Dumper;

my $re =  qr/^(.*?)([[{])([^]}]+)([]}])(.*?)$/;
my ($base, @ranges);

sub new {
	my ($class, $template) = (@_);
	croak "Usage: my \$obj = new GenURLs 'template[1-10]/{a,b,c}[-1-+1]'"
		unless $template and $template =~ $re;

	my $i = 0;
	while( $template =~ s/$re/$1\cA$i\cA$5/g ) {
		croak "Bad template: '$template' $1, $2, $3, $4, $5"
			unless defined $4
			and 1+index( '[]{}', "$2$4");

		if ( $2 eq '[' ) {
			my $range = $3;
			my ($start, $stop) = $range =~ /(\d+)-(\d+)/;
			croak "Bad range: [$start-$stop]" unless $start < $stop;

			push @ranges, {type=>'RANGE', start=>$start, stop=>$stop};
		}
		else {
			my @list= split',', $3;
			push @ranges, {type=>'LIST', last=>,0, values=>\@list };
		}
		$i++;
	}
	$base = $template;
#	print "$base\n", Dumper( \@ranges);
	return bless [], $class;
}

sub getIterator {
	my ($self, $nBatch) = @_;
	my $state = {last=>$base, batch=>$nBatch, nextIdx=>$#ranges, ranges=>$#ranges };
	return
		sub {
			my ($count, @list) = ($state->{nBatch}, ());
			my $range = $state->{nextRange} || $state->{ranges};

			do {
				incrRange( $state, $range );
				(my $item = $state->{last}) =~ tr/\cA//d;
				print "Pushing : '$item'";
				push(@list, $item);
			} while (--$count and $range >=0);
			$state->{nextRange} = $range if $range >=0;
			return @list;
		};
}

sub incrRange {
	my ($state, $range) = @_;
	my $carry = 0;

	if ($ranges[$range]{type} eq 'RANGE') {
		$state->{last} =~
			s[((?:\cA(?:[^\cA]+)\cA){$range})(?:\cA([^\cA]+)\cA)]
			 [
				my $val = $2 + 1;
				if ($val >= $ranges[$range]{stop}) {
					$val = $ranges[$range]{start};
					$carry = 1;
				}
				"$1\cA$val\cA";
			 ]e;
	}
	else {
		$state->{last} =~
			s[((?:\cA(?:[^\cA]+)\cA){$range})(?:\cA([^\cA]+)\cA)]
			 [
				my $iVal = $ranges[$range]{last}++;
				if ($iVal > $#{$ranges[$range]{values}}) {
					$iVal = $ranges[$range]{last} = 0;
					$carry = 1;
				}
				"$1\cA@{$ranges[$range]{values}}[$iVal]\cA";
			 ]e;
	}
	incrRange($state, $range - 1) if $carry and $range >= 0;
	#print $state->{last};
}

package main;

my $genUrl = new GenURLs( 'test[1-10]{a,b,c}' );

my $iterator = $genUrl->getIterator(100);

print $iterator->();
__END__