#!/bin/bash
set -euo pipefail

(
	set -euo pipefail
	flock -x -w 10 200 || exit 1

	export LVM_SUPPRESS_FD_WARNINGS=1
	DOMAIN=${1:?VM name musst be passed!}
	DOMAIN_MOUNTBASE="/var/backup-client/vm-mountpoint"

	function unfreeze_vm {
		virsh resume "$DOMAIN" > /dev/null || true
	}

	function delete_snapshots {
		cleanup_vmmount > /dev/null 2>&1
		for i in $DISKS; do
			extract_lvm
			SNAPSHOT="/dev/$VG/backup-$DEVICE"
			lvremove -f "$SNAPSHOT" > /dev/null 2>&1 || true
		done
		for i in $DISKS_QCOW2; do
			extract_lvm_qcow2
			SNAPSHOT="/dev/$VG/backup-$DEVICE"
			lvremove -f "$SNAPSHOT" > /dev/null 2>&1 || true
		done
	}

	function cleanup_vmmount {
		umount -l $DOMAIN_MOUNTBASE/* || true
		rmdir ${DOMAIN_MOUNTBASE:?}/* || true
		rm "$DOMAIN_MOUNTBASE/config.xml" || true
	}

	function extract_lvm {
		DISK=`echo $i | awk -F, '{print $1}'`
		DEVICE=`echo $i | awk -F, '{print $2}'`
		VG=`lvs --noheadings -o vg_name "$DISK" | tr -d ' '`
		LV=`lvs --noheadings -o lv_name "$DISK" | tr -d ' '`
	}

	function extract_lvm_qcow2 {
		DISK=`echo $i | awk -F, '{print $1}'`
		DEVICE=`echo $i | awk -F, '{print $2}'`
		DEVICEPATH=`df "$DISK" | awk '{print $1}' | tail -n1`
		MOUNTPOINT=`df "$DISK" | awk '{print $6}' | tail -n1`
		RELIMAGEPATH="${DISK#$MOUNTPOINT}"
		VG=`lvs --noheadings -o vg_name "$DEVICEPATH" | tr -d ' '`
		LV=`lvs --noheadings -o lv_name "$DEVICEPATH" | tr -d ' '`
	}

	function backup_vm {
		# get a list of disks
		DISKS=`virsh domblklist "$DOMAIN" --details \
			| sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' \
			| grep ^block \
			| grep -v swap \
			| awk '{printf "%s,%s ",$4, $3}'`
		DISKS_QCOW2=`virsh domblklist "$DOMAIN" --details \
			| sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//' \
			| grep ^file \
			| grep -v swap \
			| grep '.qcow2' \
			| awk '{printf "%s,%s ",$4, $3}'`
		echo "backing up $DOMAIN:  $DISKS $DISKS_QCOW2"

		trap "unfreeze_vm || true; delete_snapshots" INT TERM EXIT

		# in case an earlier script crashed we have to clear snapshots
		delete_snapshots

		# freez vm
		virsh suspend "$DOMAIN" > /dev/null || true

		# create disk snapshots
		for i in $DISKS; do
			extract_lvm
			lvcreate -L16G -s -n "backup-$DEVICE" "$DISK" > /dev/null
		done

		# create snapshots of all volumes containing qcow2 images
		for i in $DISKS_QCOW2; do
			extract_lvm_qcow2
			lvcreate -L16G -s -n "backup-$DEVICE" "$DEVICEPATH" > /dev/null
		done

		# dump vm config
		virsh dumpxml "$DOMAIN" > "$DOMAIN_MOUNTBASE/config.xml"

		unfreeze_vm
		trap "delete_snapshots" INT TERM EXIT

		# mount disks snapshots
		for i in $DISKS; do
			extract_lvm
			SNAPSHOT="/dev/$VG/backup-$DEVICE"
			fsck -y "$SNAPSHOT" > /dev/null 2> /dev/null

			(
				mkdir "$DOMAIN_MOUNTBASE/$DEVICE"
				mount -o ro "$SNAPSHOT" "$DOMAIN_MOUNTBASE/$DEVICE"
			) 2> /dev/null
		done

		# mount qcow2 disk images backing storage
		for i in $DISKS_QCOW2; do
			extract_lvm_qcow2
			SNAPSHOT="/dev/$VG/backup-$DEVICE"
			fsck -y "$SNAPSHOT" > /dev/null 2> /dev/null
			(
				mkdir "$DOMAIN_MOUNTBASE/IMAGECONTAINER_$DEVICE"
				# to be able to run fsck inside the vm we have to mount the containers r/w
				mount -o rw "$SNAPSHOT" "$DOMAIN_MOUNTBASE/IMAGECONTAINER_$DEVICE"

				mkdir "$DOMAIN_MOUNTBASE/$DEVICE"
				guestmount -m /dev/sda -a "$DOMAIN_MOUNTBASE/IMAGECONTAINER_$DEVICE/$RELIMAGEPATH" "$DOMAIN_MOUNTBASE/$DEVICE"
			) 2> /dev/null
		done

{% if backup_backend == 'restic' %}
		# restic backend
		source /etc/backup-client/restic.env
		restic backup \
			--cleanup-cache {% if not backup_restic_cache %} --no-cache{% endif %} \
			--verbose \
			--host "$DOMAIN" \
			--exclude-file "/etc/backup-client/vms/$DOMAIN/exclude_files" \
			--exclude="$DOMAIN_MOUNTBASE/IMAGECONTAINER_*" \
			"$DOMAIN_MOUNTBASE"
{% endif %}

		# delete snapshot
		delete_snapshots;
		trap - INT TERM EXIT
	}

	test -f "/etc/backup-client/vms/$DOMAIN/enabled" && backup_vm || echo "Backup for $DOMAIN is disabled"
) 200>/var/lock/backup-vm.lock