#!/bin/bash

helpFunction()
{
   echo ""
   echo "Usage: $0 -v VmName -t TargetHost -d TargetDataset"
   echo -e "\t-v Name of the vm to backup"
   echo -e "\t-t Backup target host name"
   echo -e "\t-s VM source zfs dataset"
   echo -e "\t-d Backup target zfs dataset"
   exit 1 # Exit script after printing help
}

while getopts "v:t:s:d:" opt
do
   case "$opt" in
      v ) VM="$OPTARG" ;;
      t ) DESTHOST="$OPTARG" ;;
      s ) SRCZFS="$OPTARG" ;;
      d ) DESTZFS="$OPTARG" ;;
      ? ) helpFunction ;; # Print helpFunction in case parameter is non-existent
   esac
done

# Print helpFunction in case parameters are empty
if [ -z "$VM" ] || [ -z "$DESTHOST" ] || [ -z "$DESTZFS" ] || [ -z "$SRCZFS" ]
then
   echo "Some or all of the parameters are empty";
   helpFunction
fi

DATE=$(date "+%Y%m%d%H%M")
DATE30=$(date -d "-30day" "+%Y%m%d")
SNAPNAME="backup_$DATE"

VMDISKS=$(virsh domblklist $VM | egrep -o vd.)
DISKSPEC=""
for disk in $VMDISKS
do
    DISKSPEC+="--diskspec $disk,file=/srv/snapshots/$VM/$VM-$disk-$SNAPNAME.qcow2,snapshot=external "
done

# create snapshot dataset
zfs create tank/snapshots/$VM

virsh snapshot-create-as --domain $VM --name $SNAPNAME --quiesce --atomic --disk-only $DISKSPEC >/dev/null 2>&1
if [ $? -ne 0 ]
then
    virsh snapshot-create-as --domain $VM --name $SNAPNAME --disk-only $DISKSPEC >/dev/null 2>&1
    if [ $? -ne 0 ]
    then
        echo "VM snapshot creation failed" >&2
        exit 1
    else
	echo "Snapshot created without --quiesce"
    fi
fi

zfs snapshot "$SRCZFS"@"$SNAPNAME"
if [ $? -ne 0 ]
then
    echo "ZFS snapshot creation failed" >&2
    exit 1
fi

for disk in $VMDISKS
do
    virsh blockcommit $VM $disk --pivot --active >/dev/null
done

VMDISKS=$(virsh domblklist $VM | egrep vd.)
for disk in $VMDISKS
do
    if [[ $disk == *"snapshot"* ]]
    then
	echo "Snapshot deletion failed for $disk" >&2
    fi
done

virsh snapshot-delete $VM $SNAPNAME --metadata

SUCCESS=$(zfs get backup:success -H -o value $SRCZFS)
if [[ $SUCCESS == "true" ]]
then
    LASTBACKUP=$(zfs get backup:date -H -o value $SRCZFS)
    LASTSNAP="backup_$LASTBACKUP"
    zfs send -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L 500M | ssh $DESTHOST sudo zfs recv -F $DESTZFS
else
    zfs send "$SRCZFS"@"$SNAPNAME" | pv -L 500M | ssh $DESTHOST sudo zfs recv -F $DESTZFS
fi
if [ $? -eq 0 ]
then
    zfs set backup:success="true" $SRCZFS
    zfs set backup:date="$DATE" $SRCZFS
else
    zfs set backup:success="false" $SRCZFS
    zfs set backup:failed="$DATE" $SRCZFS
fi


zfs destroy tank/snapshots/$VM