# vim syntax=sh
if type zfs > /dev/null 2>&1; then
  SNAP_METHOD="zfs"
  STATE_PATH="/vms/state"
else
  SNAP_METHOD="lvm"
  STATE_PATH="/var/lib/libvirt/qemu/save"
fi

lvm_snapshot() {
  local volume=$1 snapname=$2
  sudo lvcreate -sn $volume-$snapname -l 100%ORIGIN vms/$volume
}

lvm_revert() {
  local volume=$1 snapname=$2
  sudo lvconvert --merge vms/$volume-$snapname -i 5
  sudo lvcreate -sn $volume-$snapname -l 100%ORIGIN vms/$volume  # keep snapshot around
}

lvm_discard() {
  local volume=$1 snapname=$2
  sudo lvremove -f vms/$volume-$snapname
}

zfs_snapshot() {
  local volume=$1 snapname=$2
  sudo zfs snapshot vms/$volume@$snapname
  sudo zfs clone vms/$volume@$snapname vms/$volume-$snapname
  sudo zfs promote vms/$volume-$snapname
}

zfs_revert() {
  local volume=$1 snapname=$2
  sudo zfs destroy vms/$volume
  sudo zfs clone vms/$volume-$snapname@$snapname vms/$volume
}

zfs_discard() {
  local volume=$1 snapname=$2
  clones="$(sudo zfs get -H clones vms/$volume-$snapname@$snapname | cut -f3)"
  case $clones in
  "" )
    sudo zfs destroy vms/$volume-$snapname@$snapname
    sudo zfs destroy vms/$volume-$snapname
    ;;
  vms/$volume )
    sudo zfs promote vms/$volume
    sudo zfs destroy vms/$volume-$snapname
    sudo zfs destroy vms/$volume@$snapname
    ;;
  * )
    echo "Can't remove snapshot vms/$volume-$snapname@$snapname since it has clones: $clones"
  esac
}

virsh_all() {
  local action=$1
  shift
  echo "$@" | xargs -P0 -n1 virsh $action | sed -n '/./p'
}

snapshot_vms() {
  local snapname=$1 domain snap_arg
  shift
  sudo mkdir -p "$STATE_PATH"
  sudo chown libvirt-qemu:kvm "$STATE_PATH"
  virsh_all suspend "$@"
  for domain; do
    ${SNAP_METHOD}_snapshot $domain $snapname
    snap_arg=""
    case $domain in
    fuel )
      snap_arg="--diskspec hdb,snapshot=no"
      ;;
    compute-* )
      snap_arg="--diskspec hdb,snapshot=no"
      ${SNAP_METHOD}_snapshot $domain-ceph $snapname
      ;;
    esac
    virsh snapshot-create-as $domain $domain-$snapname --atomic --memspec "$STATE_PATH/$domain-$snapname" --diskspec hda,snapshot=no $snap_arg
  done
  virsh_all resume "$@"
}

revert_vms() {
  local snapname=$1 domain
  shift
  virsh_all destroy "$@"
  for domain; do
    ${SNAP_METHOD}_revert $domain $snapname
    case $domain in
    compute-* )
      ${SNAP_METHOD}_revert $domain-ceph $snapname
      ;;
    esac
    virsh restore "$STATE_PATH/$domain-$snapname" --paused
  done
  virsh_all resume "$@"
}

discard_snapshots() {
  local snapname=$1 domain
  shift
  for domain; do
    ${SNAP_METHOD}_discard $domain $snapname
    case $domain in
    compute-* )
      ${SNAP_METHOD}_discard $domain-ceph $snapname
      ;;
    esac
	virsh snapshot-delete $domain $domain-$snapname --metadata
    sudo rm -f "$STATE_PATH/$domain-$snapname"
  done
}

zfs_transfer() {
  local volume=$1 snapname=$2 target=$3
  local dataset="vms/$volume-$snapname@$snapname"
  sudo zfs send "$dataset" | pv -cN $domain -s "$(sudo zfs list -Hp "$dataset" | cut -f4)" | ssh $target sudo zfs recv -vd vms
}

transfer_snapshots() {
  local snapname=$1 target=$2 domain
  shift; shift
  if [ "$SNAP_METHOD" != "zfs" ]; then
    echo "Can transfer only ZFS snapshots"
    return 1
  fi
  if ! type pv > /dev/null 2>&1; then
    sudo apt-get install -y pv
  fi
  if ! ssh -o KbdInteractiveAuthentication=no $target true; then
    echo "Please set up passwordless SSH to node $target"
    return 1
  fi
  if ! ssh $target sudo -nv 2> /dev/null; then
    echo "Please set up passwordless sudo on node $target"
    return 1
  fi
  ssh $target sudo mkdir -p "$STATE_PATH"
  for domain; do
    ${SNAP_METHOD}_transfer $domain $snapname $target
    case $domain in
    compute-* )
      ${SNAP_METHOD}_transfer $domain-ceph $snapname $target
      ;;
    esac
    local state_file="$STATE_PATH/$domain-$snapname"
    sudo pv "$state_file" | ssh $target sudo "sh -c \"cat > \\\"$state_file\\\"\""
  done
}