use v6.d;
unit module MaildirIndexer::ScanDir;

sub scan-dir(IO() $path --> Supply) is export {
    supply {
        my %watched-dirs;

        sub add-dir(IO::Path $dir, :$initial) {
            %watched-dirs{$dir} = True;

            CATCH { when X::IO::Dir { }; default { warn $_ } }
            
            whenever $dir.watch {
                my $path-io = .path.IO;
                emit $path-io;
                when $path-io.e && $path-io.d {
                    add-dir($path-io) unless %watched-dirs{$path-io};
                }
                when !$path-io.e {
                    %watched-dirs{$path-io}:delete
                }
            }

            for $dir.dir {
                emit $_;
                when .e && .d {
                    add-dir($_);
                }
            }
        }

        add-dir($path);
    }
}