use strict;
use warnings;

package incdec;

sub incdec {
	my ($line, $point_position, $is_backward) = @_;

	$point_position ||= 0;
	$is_backward ||= 0;

	my $original_point_position = $point_position;

	# If point is within a number, move it to ensure we match the whole number
	# rather than only part of its digits.
	my $line_start = '';
	my $line_part = $line;
	while ($point_position < length($line_part)) {
		$line_part =~ /(\d+)/;

		# If `$point_position` is within the matched number, we can stop.
		if ($-[0] <= $point_position && $point_position < $+[0]) {
			last;
		}

		# Continue the loop if point is further right than the end of the match.
		if ($point_position >= $+[0]) {
			# Store the line part that we don't increment so we can include it at the end.
			$line_start .= substr($line_part, 0, $+[0]);

			# Match starting in the next part of the string next iteration.
			$line_part = substr($line_part, $+[0]);

			# Adjust point position according to the new line part.
			$point_position -= $+[0];

			next;
		}
		else {
			last;
		}
	}

	# Idea: Loop through @- and @+ to find @- <= point < @+
	$point_position = $original_point_position;
	my @matches = $line =~ /(\d+)/g;
	print "[[@matches]]";
	# for (my $i = 0; $i < scalar @+ - 1; $i++) {
	# 	print "..$-[$i]:$+[$i]..$point_position..";
	# 	if ($point_position < $+[$i + 1]) {
	# 		print "x[$matches[$i]]x";
	# 	}
	# }
	for (my $i = 0; $i < scalar @- - 1; $i++) {
		print "..$-[$i + 1]:$+[$i]..$point_position..";
		if ($point_position > $+[$i] && $point_position <= $-[$i + 1]) {
			print "x[$matches[$i]]x";
		}
	}

	# Final match, final match before point

	$line_part =~ s/(\d+)/$1+1/e;

	my $line_excluded = substr $line_start, 0, $original_point_position;

	$line = $line_excluded . $line_part;

	return $line;
}

1;