#!/bin/bash
################################
# Copyright 2003 Gentoo Linux
# Written by John Mylchreest <johnm@gentoo.org>
# Jul 22, 2003.

PACKAGE_DIR="/var/db/pkg/"
PORTAGE_DIR="/usr/portage"
PACKAGE_USE_FILE="/etc/portage/package.use"

CURRENT_FLAGS="$(emerge info | grep USE | sed 's:"::g' | sed 's:USE=::g')"
PORTDIR_OVERLAY="$(emerge info | grep PORTDIR_OVERLAY | sed 's:"::g' | sed 's:PORTDIR_OVERLAY=::g')"

get_packageflags() {
	echo GETFLAGS
}

if [ ! "$(whoami)" == "root" ] ; then
	echo "This script must be ran as root"
	exit 0
fi

if [ -f "${PACKAGE_USE_FILE}" ] ; then
	echo "Moving ${PACKAGE_USE_FILE} to ${PACKAGE_USE_FILE}.orig"
	mv ${PACKAGE_USE_FILE} ${PACKAGE_USE_FILE}.orig
fi

echo "Searching packages currently installed for variation on USE flags, This will take a LONG time..."

for PKG in $(grep -F -R "" ${PACKAGE_DIR}/*/*/USE | sed "s:\n: :g" | cut -f1 -d:) ; do
	PKG_CAT=${PKG/*\/\//}
	PKG_CAT=${PKG_CAT/\/*/}
	PKG_NAME=$(echo ${PKG} | sed "s:-[0-9].*::g" | sed "s:.*${PKG_CAT}/::g")
	PKG_VER=$(echo ${PKG} | sed "s:/USE::g" | sed "s:.*${PKG_CAT}/${PKG_NAME}-::g")			
	PKG_USE="$(cat ${PACKAGE_DIR}/${PKG_CAT}/${PKG_NAME}-${PKG_VER}/USE | sed "s:\n: :g")"
	
	echo "Checking: ${PKG_CAT}/${PKG_NAME}-${PKG_VER}"
	
	if [ -f "${PORTDIR_OVERLAY}/${PKG_CAT}/${PKG_NAME}/${PKG_NAME}-${PKG_VER}.ebuild" ] ; then
		echo "	Ebuild found in overlay"
		FILE="${PORTDIR_OVERLAY}/${PKG_CAT}/${PKG_NAME}/${PKG_NAME}-${PKG_VER}.ebuild"
	else
		FILE="${PORTAGE_DIR}/${PKG_CAT}/${PKG_NAME}/${PKG_NAME}-${PKG_VER}.ebuild"
	fi

	PKG_USEOFFSET=""
	for i in ${PKG_USE} ; do
		X=${i/-/}

		[ -z "$(echo " ${CURRENT_FLAGS}" | grep " ${i}")" ] && \
		[ -n "$(cat ${FILE}| grep "IUSE=.*${X}.*")" ] && \
			PKG_USEOFFSET="${PKG_USEOFFSET} ${i}"
	done
	
	if [ -n "${PKG_USEOFFSET}" ] ; then
		PKG_USEOFFSET=$(echo ${PKG_USEOFFSET} | sed 's: ::')
		
		echo "	Found->'${PKG_USEOFFSET}'"
		echo "${PKG_CAT}/${PKG_NAME} ${PKG_USEOFFSET}" >> ${PACKAGE_USE_FILE}
	fi
done