#! /usr/bin/env perl
# moderately tested script to untrack files that are listed in .gitignore

use strict;
use warnings;
use Getopt::Long;

my $dry_run   = 0;
my $help_me   = 0;
GetOptions(
	'dry-run!'    => \$dry_run,
	'h|help|?'    => \$help_me,
);

if ($help_me) {
	print "$0: runs 'git rm --cached' for all the files in your .gitignore\n";
	print "(This makes them untracked but not deleted)\n";
	print "Options: --dry-run: just print out which files we would remove\n";
	exit;
}

open my $fh, '<', '.gitignore' or die "Couldn't find/open .gitignore: $!";
my @patterns = <$fh>;
close $fh;
chomp @patterns;

apply_patterns('.', @patterns);

sub apply_patterns {
	my $dir = shift;
	#print "at $dir\n";
	my @patterns = @_;

	for my $pattern (@patterns) {
		if ($pattern =~ /^\s*#/ || $pattern =~ /^\s*$/) {
			next;
		} elsif ($pattern =~ /^\s*!/) {
			print "ignoring negating pattern\n";
		}

		my @files = glob($pattern);

		for my $file (grep {-e $_} map {"$dir/$_"} @files) {
			if ($dry_run) {
				print "unstage $file\n";
			} else {
				system('git', 'rm', '-q', '--ignore-unmatch', '--cached', $file);
			}
		}
	}

	apply_patterns($_, @patterns) for grep {-d} glob($dir . '/*');
}