my %Times=(
           1  		    => 'sec|second',
           60 		    => 'min|minute',
           60*60	    => 'hour',
           60*60*24     => 'day',
           60*60*24*365 => 'year'
          );

sub _dstr{
	my ($mult,$mode,$unit)=@_;
	my $str=$mult;
	if ($mode!~/^[h#]/) {
		my @names=split /\|/,$Times{$unit};
		$str.=($mode eq 'l' ? " $names[-1]" : " $names[0]");
		$str.="s" if $mult!=1;
	} elsif ($mode eq 'h') {
		$str.=substr($Times{$unit},0,1);
	}
	return $str
}

sub _duration {
	my $mode=lc(shift); #
	my $dur=shift;
	$mode=~/^[hml#]$/ or $mode="m";
	my $negative=$dur<0 ? ($mode eq "l" ? "negative " : $mode eq "m" ? "neg " : "-")
	                    : "";
	my @units;
	foreach my $unit (sort {$b <=> $a} keys %Times) {
		next unless $unit>1;
		if ($dur>=$unit) {
			my $mult=int($dur/$unit);
			$dur-=$mult*$unit;
			push @units,_dstr $mult,$mode,$unit;
		} elsif ($mode eq "#" and @units) {
			push @units,0;
		}
	}
	if ($dur or $mode eq "#" or not @units) {
		push @units,_dstr $dur,$mode,1;
	}
	$units[-2].=" and ".pop @units
		if @units>1 and $mode eq 'l';
	return $mode ne "#" ? $negative.join( ", ",@units)
	                    : $negative.sprintf(join(":",("%02d") x @units),@units);
}