package BinaryGap;
use Modern::Perl;
# use List::MoreUtils qw(first_index); # codility does not have
use List::Util qw(max first);

use Data::Dumper;


sub solution {
   # N is an integer within the range [1..2,147,483,647]
   my ($N) = @_;
   my $max_gap = 0;
   # Make sure number is in acceptable range, if not return 0
   if (($N < 1) || ($N > '2147483647')) {
      return $max_gap;
   }
   # convert integer to binary
   my $bin_num = unpack("B*", pack("N", $N));

   # convert to array
   my @bin_array = split('',$bin_num);

   # find first 1. If there is not one, return for performance
   my $first_index;
   for (0 .. $#bin_array) {
      if ($bin_array[$_] == 1) {
         $first_index = $_;
         last;
      }
   }
   return $max_gap unless $first_index;

   # If there are less than two 1s in the array, return 0
   my $ones_total_count = grep { $_ == 1  } @bin_array;
   if ($ones_total_count < 2) {
      return $max_gap;
   }

   # If there is just one 0 in the array, return 0
   my $zeros_total_count = grep { $_ == 0  } @bin_array;
   if ($zeros_total_count < 2) {
      return $max_gap;
   }

   # Get all 1 indexes
   my @i = grep { $bin_array[$_] == 1 } 0 .. $#bin_array;
   my $last_index = $i[$#i];

   my $zero_count = 0;
   for my $index ($first_index .. $last_index) {
      my $num = $bin_array[$index];
      if ($num == 1) {
         $zero_count = 0;
      }
      else {
         $zero_count++;
         $max_gap = max($zero_count, $max_gap);
      }
   }

   return $max_gap;
}

1;

__END__

=pod

=encoding utf8

=head1 NAME

BinaryGap - Find longest sequence of zeros in binary representation of an integer. If there is none, this returns 0.