#!/bin/bash
usefile="/etc/portage/package.use/$1"
touch /tmp/usefile

function addflag
{
	if ! cat $usefile| tr ' ' '\n' |grep -e "^$1" ; then
		if [[ $(echo $1 | cut -c 1) == '-' ]]; then
			cat $usefile | sed -e 's/ '$(echo $1 | cut -c 2-)'//g' > /tmp/usefile
			printf " $1" >> /tmp/usefile
		else
			cat $usefile | sed -e 's/ -'$1'//g' > /tmp/usefile
			printf " $1" >> /tmp/usefile
		fi
	fi
}

if [[ -z $1 ]]; then
	echo "specify a package atom."
	exit
elif [[ -z $2 ]]; then
	echo "specify some flags."
	exit
elif [[ ! -f $usefile ]]; then
	if [[ ! -d $(dirname $usefile) ]]; then
		mkdir $(dirname $usefile)
	fi
	touch $usefile 
fi

printf "$1" > $usefile
for i in $(echo ${BASH_ARGV[*]} | cut -f -$(( $BASH_ARGC -1 )) -d ' ')
do
	addflag $i
	cat /tmp/usefile > $usefile
done

rm /tmp/usefile
exit