#! 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, range
+s=>$#ranges };
    return
        sub {
            my ($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__
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