#!/bin/sh
set -e

# This script only supports GPT partitions for the lx-trainer image.
ROOTPT=3
HOMEPT=4

usage_exit()
{
	echo
	echo "usage: sudo $0 src [--layer=tarball]... dest [dest]..."
	echo
	echo "example: copying image to devices: sde, sdf, sdg"
	echo "$0 lx-trainer.img /dev/sde /dev/sdf /dev/sdg"
	echo
	exit 1
}

# minimum 2 arguments
if [ $# -lt 2 ]; then
	echo "error: invalid arguments"
	usage_exit
fi

if [ `id -u` -ne 0 ]; then
	echo "error: sorry, this script must be run as root"
	exit 1
fi

# gather arguments
SRC=""
LAYERS=""
DESTS=""

for arg in $@; do
	case $arg in
	--layer=*)
		LAYERS="$LAYERS `echo $arg | sed -e 's/^--layer=//'`"
		;;
	--*)
		echo "error: unknown option: $arg"
		usage_exit
		;;
	*)
		if [ -z "$SRC" ]; then
			SRC="$arg"
		else
			DESTS="$DESTS $arg"
		fi
		;;
	esac
done

# source must be file or block device
if [ ! -f "$SRC" -a ! -b "$SRC" ]; then
	echo "error: invalid src"
	usage_exit
fi

# destination must be block device
for dest in $DESTS; do
	if [ ! -b $dest ]; then
		echo "error: invalid dest: $dest"
		usage_exit
	fi
done

# detect partion type of source
if [ "`env - /sbin/parted --script $SRC print | \
	grep 'Partition Table' | awk '{print $3}'`" != "gpt" ]; then
	echo "error: only gpt partition tables supported"
	usage_exit
fi

# delete mbr's
dd if=/dev/zero bs=10M count=1 2> /dev/null | tee $DESTS > /dev/null

# efficiently copy source to all destinations and rescan devices
echo 'monitor copy status with: sudo kill -s USR1 `pidof dd`'
dd if=$SRC bs=64M | tee $DESTS > /dev/null

echo 'setting up /home partition'

# fix partition table and add extra /home partition
for dest in $DESTS; do
	parted $dest print fix > /dev/null 2>&1
	parted --script --align optimal -- $dest mkpart /home 17GB -1MB
done

# rescan devices
while ! partprobe $DESTS 2> /dev/null; do
	echo "waiting for partprobe..."
	sleep 1
done

# wait for partitions to appear
for dest in $DESTS; do
	while [ ! -b ${dest}${ROOTPT} ]; do
		echo "waiting for ${dest}${ROOTPT}..."
		sleep 1
	done
	while [ ! -b ${dest}${HOMEPT} ]; do
		echo "waiting for ${dest}${HOMEPT}..."
		sleep 1
	done
done

# create ext4 on home partition
for dest in $DESTS; do
	mkfs.ext4 -L lxhome ${dest}${HOMEPT} > /dev/null 2>&1 &
done
wait

# setup temp directory for mountpoints
TMP_ROOT="/tmp/dd-multi-`date +%s`.$$"
rm -rf $TMP_ROOT
mkdir -p $TMP_ROOT
echo "using directory $TMP_ROOT for mount points"

for dest in $DESTS; do
	# create mountpoints
	mkdir -p ${TMP_ROOT}${dest}${ROOTPT}
	mkdir -p ${TMP_ROOT}${dest}${HOMEPT}

	# mount partitions
	mount ${dest}${ROOTPT} ${TMP_ROOT}${dest}${ROOTPT}
	mount ${dest}${HOMEPT} ${TMP_ROOT}${dest}${HOMEPT}

	# move home directories to home partition
	echo "moving /home/* to ${dest}${HOMEPT}"
	mv ${TMP_ROOT}${dest}${ROOTPT}/home/* ${TMP_ROOT}${dest}${HOMEPT}/

	# setup home partition to be mounted as /home
	echo 'LABEL=lxhome /home ext4 defaults 0 0' | \
		tee -a ${TMP_ROOT}${dest}${ROOTPT}/etc/fstab > /dev/null

	# remount home to /home
	umount ${TMP_ROOT}${dest}${HOMEPT}
	mount ${dest}${HOMEPT} ${TMP_ROOT}${dest}${ROOTPT}/home

	# unpack layers
	for tarball in $LAYERS; do
		echo "unpacking $tarball to $dest"
		tar -x -f $tarball --numeric-owner \
			-C ${TMP_ROOT}${dest}${ROOTPT}
	done

	# unmount partitions
	umount ${TMP_ROOT}${dest}${ROOTPT}/home
	umount ${TMP_ROOT}${dest}${ROOTPT}
done

# cleanup temp directory
rm -rf $TMP_ROOT

echo "done, no errors"