#!/bin/bash

helpFunction()
{
   echo ""
   echo "Usage: $0 -v VmName -t TargetHost -d TargetDataset -l LIMIT"
   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"
   echo -e "\t-l Limit Bandwith"
   exit 1 # Exit script after printing help
}

while getopts "v:t:s:d:l:" opt
do
   case "$opt" in
      v ) VM="$OPTARG" ;;
      t ) DESTHOST="$OPTARG" ;;
      s ) SRCZFS="$OPTARG" ;;
      d ) DESTZFS="$OPTARG" ;;
      l ) LIMIT="$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" ] || [ -z "$LIMIT" ]
then
   echo "Some or all of the parameters are empty";
   helpFunction
fi

echo "$(date +%Y-%m-%d_%H:%M:%S): Starting Backup of $VM"

DAYS=$(zfs get backup:days -H -o value $SRCZFS)
if [[ $DAYS == "-" ]]
then
    DAYS=7
fi
echo "$(date +%Y-%m-%d_%H:%M:%S): Keeping backups for $DAYS days"
DAYS=$(($DAYS + 1))
DATE=$(date "+%Y%m%d%H%M")
DATEOLD=$(date -d -"$DAYS"day "+%Y%m%d")
SNAPNAME="backup_$DATE"


abortFunction()
{
    zfs set backup:success="false" $SRCZFS
    zfs set backup:failed="$DATE" $SRCZFS
    exit 1
}

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

# create virsh xml-dump of vm
virsh dumpxml $VM > /srv/vms/$VM/vm-$VM.xml

echo "$(date +%Y-%m-%d_%H:%M:%S): Create VM snapshot of $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 [ $? -ne 0 ]
    then
        echo "VM snapshot creation failed" >&2
        abortFunction
    else
	echo "$(date +%Y-%m-%d_%H:%M:%S): Snapshot created without --quiesce"
    fi
fi

echo "$(date +%Y-%m-%d_%H:%M:%S): Creating ZFS snapshot $SRCZFS@$SNAPNAME"
zfs snapshot "$SRCZFS"@"$SNAPNAME"
if [ $? -ne 0 ]
then
    echo "ZFS snapshot creation failed" >&2
    abortFunction
fi

echo "$(date +%Y-%m-%d_%H:%M:%S): Deleting vm disk snapshots"
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
	abortFunction
    fi
done

virsh snapshot-delete $VM $SNAPNAME --metadata > /dev/null

SUCCESS=$(zfs get backup:success -H -o value $SRCZFS)
LASTBACKUP=$(zfs get backup:date -H -o value $SRCZFS)
if [[ $SUCCESS == "true" ]]
then
    LASTSNAP="backup_$LASTBACKUP"
    echo "$(date +%Y-%m-%d_%H:%M:%S): Sending incremental snapshot from $LASTSNAP"
    ssh $DESTHOST sudo zfs rollback "$DESTZFS"@"$LASTSNAP"
    zfs send -R -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv $DESTZFS
else
    if [[ $LASTBACKUP != "-" ]]
    then
        LASTSNAP="backup_$LASTBACKUP"
	echo "$(date +%Y-%m-%d_%H:%M:%S): Trying to send incremental snapshot from $LASTSNAP"
	ssh $DESTHOST sudo zfs rollback "$DESTZFS"@"$LASTSNAP"
	zfs send -R -i "$SRCZFS"@"$LASTSNAP" "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv $DESTZFS
    else 
        echo "$(date +%Y-%m-%d_%H:%M:%S): Sending full snapshot"
        zfs send -R "$SRCZFS"@"$SNAPNAME" | pv -L $LIMIT | ssh $DESTHOST sudo zfs recv -F $DESTZFS
    fi
fi
if [ $? -eq 0 ]
then
    zfs set backup:success="true" $SRCZFS
    zfs set backup:date="$DATE" $SRCZFS
    zfs set backup:failed="-" $SRCZFS
    if [ -n $LASTSNAP ]
    then
	echo "$(date +%Y-%m-%d_%H:%M:%S): Deleting old ZFS snapshot $LASTSNAP"
        zfs destroy "$SRCZFS"@"$LASTSNAP"
    fi
else
    abortFunction
fi

zfs destroy tank/snapshots/$VM

# cleanup old backups

OLDSNAPS=$(ssh $DESTHOST zfs list -r -t snapshot -o name $DESTZFS 2>/dev/null | grep $DATEOLD)
if [ ${#OLDSNAPS} -gt 0 ]
then
    for oldsnap in $OLDSNAPS
    do
	echo "$(date +%Y-%m-%d_%H:%M:%S): Deleting old snapshots on target"
	ssh $DESTHOST sudo zfs destroy $oldsnap
    done
else
    echo "$(date +%Y-%m-%d_%H:%M:%S): No old snapshots to cleanup on target"
fi

echo "$(date +%Y-%m-%d_%H:%M:%S): Backup Completed"