#!/bin/sh


usage() {
	echo "usage: ${0##*/} [options] name [stage_tarball [custom_script]]"
}


usage_full() {
	usage
	printf '
Create a libvirt virtual machine running Gentoo Linux

positional arguments:
  name                  The libvirt domain name for the VM
  stage_tarball         Path to the Gentoo stage tarball to extract to the
                        virtual machine filesystem
  custom_script         Path to a script to run in the virtual machine chroot
                        before powering it on

optional arguments:
  -h, --help            show this help message and exit
  --hostname, -H        The hostname of the VM  (defaults to the libvirt
                        domain name, in all lower case)
  --kernel-pkg, -K      Path to a tarball containing a kernel and modules
  --pool, -p            The libvirt storage pool in which to create the
                        virtual disk
  --disk-size           The size of virtual disk to create (default 6 GB)
  --disk-format         The image format of the virtual disk (default qcow2)
  --vram, -r            The amount of RAM to allocate to the VM
  --vcpus, -c           The number of virtual CPUs to allocate to the VM
  --vnet, -n            The network adapter on the host to connect to the VM
  --timezone, -Z        The timezone to set in the VM
'
}

invalid_arg() {
	usage >&2
	echo "${0##*/}: Unrecognized argument: $1" >&2
	exit 2;
}


while [ $# -gt 0 ]; do
	case $1 in
	--hostname|-H)
		shift
		VHOSTNAME=$1
		shift
		;;
	--kernel-pkg|-K)
		shift
		KERNEL_PKG=$1
		shift
		;;
	--pool|-p)
		shift
		POOL=$1
		shift
		;;
	--disk-size|-s)
		shift
		VDISKSIZE=$1
		shift
		;;
	--disk-format|-f)
		shift
		VDISKFORMAT=$1
		shift
		;;
	--vram|-r)
		shift
		VRAM=$1
		shift
		;;
	--vcpus|-c)
		shift
		VCPUS=$1
		shift
		;;
	--vnet|-n)
		shift
		VNET=$1
		shift
		;;
	--timezone|-Z)
		shift
		TIMEZONE=$1
		shift
		;;
	--help|-h)
		usage_full
		exit 0
		;;
	-*)
		invalid_arg $1
		;;
	*)
		if [ -z "${DOMNAME}" ]; then
			DOMNAME=$1
			shift
		elif [ -z "${STAGE_TBZ}" ]; then
			STAGE_TBZ=$1
			shift
		elif [ -z "${CUSTOMIZE}" ]; then
			CUSTOMIZE=$1
			shift
		else
			invalid_arg $1
		fi
		;;
	esac
done


set -e


if [ -z "${DOMNAME}" ]; then
	usage >&2
	exit 2
fi

: ${VHOSTNAME:=$(printf "${DOMNAME}" | tr '[A-Z]' '[a-z]')}
: ${POOL:=default}
: ${TIMEZONE:=America/Chicago}

unset $(env | awk -F= '/^LC_/{print $1}')
export LC_ALL=C

mountpoint=${TMPDIR:-/tmp}/${VHOSTNAME}
mkdir ${mountpoint}


virsh vol-create-as ${POOL} ${DOMNAME}.img \
	--capacity ${VDISKSIZE:-6G} \
	--format ${VDISKFORMAT:-qcow2}
vol_path=$(virsh vol-path ${DOMNAME}.img ${POOL})

echo 'Creating logical volumes and filesystems ...'
i=$(pgrep -fa ^nbd | sort -k2r | sed -rn '1s/[0-9]+\s+nbd//p')
blkdev=/dev/nbd$((${i:--1} + 1))
unset i

sudo /bin/sh -e <<EOS
qemu-nbd -c ${blkdev} ${vol_path}

sgdisk -a 4096 -Z -g \
	-n 1::+1M \
	-t 1:EF02 \
	-c 1:'BIOS boot partition' \
	-n 2::+32M \
	-c 2:'Linux filesystem' \
	-n 3:: \
	-t 3:8E00 \
	-c 3:'Linux LVM' \
	${blkdev}

pvscan > /dev/null

pvcreate ${blkdev}p3
vgcreate ${VHOSTNAME} ${blkdev}p3
lvcreate -nswap -L1G ${VHOSTNAME}
lvcreate -nroot -L300M ${VHOSTNAME}
lvcreate -nusr -L1200M ${VHOSTNAME}
lvcreate -nvar -L600M ${VHOSTNAME}
lvcreate -nopt -L100M ${VHOSTNAME}
lvcreate -nhome -L100M ${VHOSTNAME}
mkswap -Lswap /dev/${VHOSTNAME}/swap
mkfs.ext4 -q -Lboot ${blkdev}p2
for v in root usr var opt home; do
	mkfs.xfs -q -L\$v /dev/${VHOSTNAME}/\$v
done
EOS

[ -z "${STAGE_TBZ}" ] && exit 0

echo 'Mounting filesystems ...'
sudo /bin/sh -e <<EOS
mount /dev/${VHOSTNAME}/root ${mountpoint}

install -d ${mountpoint}/boot
mount ${blkdev}p2 ${mountpoint}/boot

for v in usr var opt home; do
	install -d ${mountpoint}/\$v
	mount /dev/${VHOSTNAME}/\$v ${mountpoint}/\$v
done
EOS

echo 'Extracting stage tarball ...'
sudo tar -xaf "${STAGE_TBZ}" -C ${mountpoint}

echo 'Configuring system ...'
sudo /bin/sh -e <<EOS
mount -t proc proc ${mountpoint}/proc
mount -t sysfs sysfs ${mountpoint}/sys
mount -obind /dev ${mountpoint}/dev
chroot ${mountpoint} grub2-install ${blkdev}
cat > ${mountpoint}/boot/grub/grub.cfg <<EOF
timeout=1

menuentry 'Gentoo Linux' {
	root=hd0,gpt2
	linux /vmlinuz root=/dev/${VHOSTNAME}/root dolvm net.ifnames=0 quiet
	initrd /initramfs
}
EOF

sed -i s/localhost/${VHOSTNAME}/ ${mountpoint}/etc/conf.d/hostname

cat > ${mountpoint}/etc/fstab <<EOF
LABEL=swap	none	swap	sw	0 0
LABEL=boot	/boot	ext4	noauto,noatime	1 2
/dev/${VHOSTNAME}/root	/	xfs	ro,noatime	0 1
/dev/${VHOSTNAME}/usr	/usr	xfs	ro,noatime	0 2
/dev/${VHOSTNAME}/var	/var	xfs	noatime	0 2
/dev/${VHOSTNAME}/opt	/opt	xfs	ro,noatime	0 2
/dev/${VHOSTNAME}/home	/home	xfs	noatime	0 2
tmpfs	/tmp	tmpfs	defaults	0 0
EOF

rm -rf ${mountpoint}/run/openrc
ln -snf /proc/self/mounts ${mountpoint}/etc/mtab
ln -snf /run/resolv.conf ${mountpoint}/etc/resolv.conf
ln -snf /run/ntp.conf ${mountpoint}/etc/ntp.conf

ln -snf /usr/share/zoneinfo/${TIMEZONE} ${mountpoint}/etc/localtime
echo ${TIMEZONE} > ${mountpoint}/etc/timezone

passwd -R ${mountpoint} -d root
EOS


if [ -n "${KERNEL_PKG}" ]; then
	echo 'Extracting kernel package ...'
	sudo tar --no-same-owner --no-same-permissions --strip-components=1 \
		--dereference -xaf "${KERNEL_PKG}" -C ${mountpoint}
fi


if [ -f "${CUSTOMIZE}" ]; then
	echo 'Customizing ...'
	sudo /bin/sh "${CUSTOMIZE}"
fi


echo 'Cleaning up ...'
awk '$5~/'${VHOSTNAME}'/{print $5}' /proc/self/mountinfo | tac \
	| xargs sudo umount
sudo vgchange -an ${VHOSTNAME}
sudo qemu-nbd -d ${blkdev}

virt-install --name ${DOMNAME} \
	--ram ${VRAM:-1024} \
	--vcpus ${VCPUS:-2} \
	--os-type linux \
	--os-variant rhel7 \
	--boot hd \
	--disk ${vol_path} \
	--network bridge=${VNET:-br0} \
	--graphics vnc \
	--video cirrus \
	--memballoon model=virtio \
	--noautoconsole

rmdir ${mountpoint}