#!/bin/sh

set -e

UPDATE_TO="${UPDATE_TO:-no}"
TIMESTAMP_SAVE="$(date -u +%Y%m%dT%H%M%SZ)"
TEMP_DIR="/dev/shm/temp-livegui-save-changes"

mkdir -p ${TEMP_DIR}/root.dir

if [ "${UPDATE_TO}" != "no" ] && [ -f "${UPDATE_TO}" ] && [[ "$(file -b ${UPDATE_TO})" =~ "ISO 9660 CD-ROM filesystem data" ]]; then
	echo "Updating/saving persistent image against file \"${UPDATE_TO}\"..."
	mkdir -p ${TEMP_DIR}/{iso,livecd}
	mount -o loop "${UPDATE_TO}" ${TEMP_DIR}/iso
	mount -t squashfs ${TEMP_DIR}/iso/image.squashfs ${TEMP_DIR}/livecd
	TIMESTAMP_ORIG="$(ls -v ${TEMP_DIR}/iso/snapshots | tail -n 1 | sed -e 's/gentoo-//' -e 's/.tar.bz2.DIGESTS//')"
else
	if [ "${UPDATE_TO}" != "no" ]; then
		UPDATE_TO="no"
	fi
	echo "Saving persistent image against current environment..."
	TIMESTAMP_ORIG="$(ls -v /mnt/cdrom/snapshots | tail -n 1 | sed -e 's/gentoo-//' -e 's/.tar.bz2.DIGESTS//')"
fi

mount -o bind / ${TEMP_DIR}/root.dir

rsync -XxAaHm --exclude /tmp/ --exclude /var/tmp/ --exclude /dev/ \
$(mountpoint -q /home && echo -n '--exclude /home/') \
$([ "${UPDATE_TO}" != "no" ] && \
echo -n '--exclude /bin/ --exclude /lib/ --exclude /lib64/ --exclude /opt/ --exclude /sbin/ --exclude /usr/ --exclude /var/db/pkg/') \
--compare-dest=/mnt/livecd ${TEMP_DIR}/root.dir/ ${TEMP_DIR}/new.dir

umount ${TEMP_DIR}/root.dir

cd ${TEMP_DIR}/new.dir

#TODO: find a safer line to replace this
for i in `find . -type d | sort -r`; do if [ -z "$(ls -A ${i})" ]; then rmdir "${i}"; fi; done;

if [ "${UPDATE_TO}" != "no" ]; then
	cd etc
	for i in `find . -type f`; do
		if [ -f "${TEMP_DIR}/livecd/etc/${i}" ] && ! [[ "$(md5sum ${TEMP_DIR}/livecd/etc/${i})" =~ "$(md5sum ${i} | sed -e 's/ .*//')" ]]; then
			cp -a "${TEMP_DIR}/livecd/etc/${i}" $(echo -n "${i}" | sed -E "s@($(dirname ${i}))(\/)([^\/]*$)@\1/._cfg0001_\3@")
		fi
	done
	mkdir -p ${TEMP_DIR}/overlay/{work,upper,merge}
	mount -t overlay overlay -olowerdir=${TEMP_DIR}/new.dir:${TEMP_DIR}/livecd,workdir=${TEMP_DIR}/overlay/work,upperdir=${TEMP_DIR}/overlay/upper ${TEMP_DIR}/overlay/merge
	mount -t proc /proc ${TEMP_DIR}/overlay/merge/proc
	mount --rbind /sys ${TEMP_DIR}/overlay/merge/sys
	mount --bind /dev ${TEMP_DIR}/overlay/merge/dev
	mount --bind /dev/pts ${TEMP_DIR}/overlay/merge/dev/pts
	mount --bind /dev/mqueue ${TEMP_DIR}/overlay/merge/dev/mqueue
	mount -t tmpfs tmpfs ${TEMP_DIR}/overlay/merge/dev/shm
	mount --bind /run ${TEMP_DIR}/overlay/merge/run

	for i in `grep -Eh "^(DISTDIR|PKGDIR|location)" /etc/portage/make.conf /etc/portage/repos.conf/* | sed -e 's/.*=//' -e 's/[" ]//g'`; do
		[ -d "${i}" ] && mkdir -p ${TEMP_DIR}/overlay/merge${i} && mount -o bind ${i} ${TEMP_DIR}/overlay/merge${i}
	done

	cd ${TEMP_DIR}/overlay/merge/var
	rm db && ln -s ../usr/livecd/db db

	CHROOT_EMERGE=''
	if [ -f "${TEMP_DIR}/overlay/merge/usr/bin/emerge" ]; then
		CHROOT_EMERGE="${CHROOT_EMERGE} && source /etc/profile && emerge --sync && emerge -vquakND @world"
		CHROOT_EMERGE="${CHROOT_EMERGE} && (([ -L '/usr/bin/smart-live-rebuild' ] && smart-live-rebuild -- -aq) || true)"
		CHROOT_EMERGE="${CHROOT_EMERGE} && etc-update"
	fi

	until chroot ${TEMP_DIR}/overlay/merge /bin/bash -c "etc-update${CHROOT_EMERGE}"; do
		echo "chroot, etc-update, or package update did not exit cleanly... fix what failed in this chroot shell, exit 0, then try again."
		chroot ${TEMP_DIR}/overlay/merge /bin/bash
	done

	mkdir -p ${TEMP_DIR}/final.dir
	cd ${TEMP_DIR}/final.dir

	rsync -XxAaHm --exclude /tmp/ --exclude /var/tmp/ --exclude /dev/ \
	$(mountpoint -q /home && echo -n '--exclude /home/') \
	--compare-dest=${TEMP_DIR}/livecd ${TEMP_DIR}/overlay/merge/ ${TEMP_DIR}/final.dir

	umount -R ${TEMP_DIR}/{overlay/merge,livecd,iso}

	#TODO: find a safer line to replace this
	for i in `find . -type d | sort -r`; do if [ -z "$(ls -A ${i})" ]; then rmdir "${i}"; fi; done;
fi

mksquashfs . ../persist-${TIMESTAMP_ORIG}-${TIMESTAMP_SAVE}.squashfs -comp gzip -b 131072

echo "Persistent image saved as ${TEMP_DIR}/persist-${TIMESTAMP_ORIG}-${TIMESTAMP_SAVE}.squashfs ... Copy it to your boot medium."