#!/usr/bin/bash
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set -eo pipefail

# CloudStack B&R NAS Backup and Recovery Tool for KVM

# TODO: do libvirt/logging etc checks

### Declare variables ###

OP=""
VM=""
NAS_TYPE=""
NAS_ADDRESS=""
MOUNT_OPTS=""
BACKUP_DIR=""
DISK_PATHS=""
QUIESCE=""
logFile="/var/log/cloudstack/agent/agent.log"

EXIT_CLEANUP_FAILED=20

log() {
  [[ "$verb" -eq 1 ]] && builtin echo "$@"
  if [[ "$1" == "-ne"  || "$1" == "-e" || "$1" == "-n" ]]; then
    builtin echo -e "$(date '+%Y-%m-%d %H-%M-%S>')" "${@: 2}" >> "$logFile"
  else
    builtin echo "$(date '+%Y-%m-%d %H-%M-%S>')" "$@" >> "$logFile"
  fi
}

vercomp() {
  local IFS=.
  local i ver1=($1) ver2=($3)

  # Compare each segment of the version numbers
  for ((i=0; i<${#ver1[@]}; i++)); do
      if [[ -z ${ver2[i]} ]]; then
          ver2[i]=0
      fi

      if ((10#${ver1[i]} > 10#${ver2[i]})); then
          return  0 # Version 1 is greater
      elif ((10#${ver1[i]} < 10#${ver2[i]})); then
          return 2  # Version 2 is greater
      fi
  done
  return 0  # Versions are equal
}

sanity_checks() {
  hvVersion=$(virsh version | grep hypervisor | awk '{print $(NF)}')
  libvVersion=$(virsh version | grep libvirt | awk '{print $(NF)}' | tail -n 1)
  apiVersion=$(virsh version | grep API | awk '{print $(NF)}')

  # Compare qemu version (hvVersion >= 4.2.0)
  vercomp "$hvVersion" ">=" "4.2.0"
  hvStatus=$?

  # Compare libvirt version (libvVersion >= 7.2.0)
  vercomp "$libvVersion" ">=" "7.2.0"
  libvStatus=$?

  if [[ $hvStatus -eq 0 && $libvStatus -eq 0 ]]; then
    log -ne "Success... [ QEMU: $hvVersion Libvirt: $libvVersion apiVersion: $apiVersion ]"
  else
    echo "Failure... Your QEMU version $hvVersion or libvirt version $libvVersion is unsupported. Consider upgrading to the required minimum version of QEMU: 4.2.0 and Libvirt: 7.2.0"
    exit 1
  fi

  log -ne "Environment Sanity Checks successfully passed"
}

### Operation methods ###

backup_running_vm() {
  mount_operation
  mkdir -p "$dest" || { echo "Failed to create backup directory $dest"; exit 1; }

  name="root"
  echo "<domainbackup mode='push'><disks>" > $dest/backup.xml
  for disk in $(virsh -c qemu:///system domblklist $VM --details 2>/dev/null | awk '/disk/{print$3}'); do
    volpath=$(virsh -c qemu:///system domblklist $VM --details | awk "/$disk/{print $4}" | sed 's/.*\///')
    echo "<disk name='$disk' backup='yes' type='file' backupmode='full'><driver type='qcow2'/><target file='$dest/$name.$volpath.qcow2' /></disk>" >> $dest/backup.xml
    name="datadisk"
  done
  echo "</disks></domainbackup>" >> $dest/backup.xml

  local thaw=0
  if [[ ${QUIESCE} == "true" ]]; then
    if virsh -c qemu:///system qemu-agent-command "$VM" '{"execute":"guest-fsfreeze-freeze"}' > /dev/null 2>/dev/null; then
      thaw=1
    fi
  fi

  # Start push backup
  local backup_begin=0
  if virsh -c qemu:///system backup-begin --domain $VM --backupxml $dest/backup.xml 2>&1 > /dev/null; then
    backup_begin=1;
  fi

  if [[ $thaw -eq 1 ]]; then
    if ! response=$(virsh -c qemu:///system qemu-agent-command "$VM" '{"execute":"guest-fsfreeze-thaw"}' 2>&1 > /dev/null); then
      echo "Failed to thaw the filesystem for vm $VM: $response"
      cleanup
      exit 1
    fi
  fi

  if [[ $backup_begin -ne 1 ]]; then
    cleanup
    exit 1
  fi

  # Backup domain information
  virsh -c qemu:///system dumpxml $VM > $dest/domain-config.xml 2>/dev/null
  virsh -c qemu:///system dominfo $VM > $dest/dominfo.xml 2>/dev/null
  virsh -c qemu:///system domiflist $VM > $dest/domiflist.xml 2>/dev/null
  virsh -c qemu:///system domblklist $VM > $dest/domblklist.xml 2>/dev/null

  while true; do
    status=$(virsh -c qemu:///system domjobinfo $VM --completed --keep-completed | awk '/Job type:/ {print $3}')
    case "$status" in
      Completed)
        break ;;
      Failed)
        echo "Virsh backup job failed"
        cleanup ;;
    esac
    sleep 5
  done

  rm -f $dest/backup.xml
  sync

  # Print statistics
  virsh -c qemu:///system domjobinfo $VM --completed
  du -sb $dest | cut -f1

  umount $mount_point
  rmdir $mount_point
}

backup_stopped_vm() {
  mount_operation
  mkdir -p "$dest" || { echo "Failed to create backup directory $dest"; exit 1; }

  IFS=","

  name="root"
  for disk in $DISK_PATHS; do
    volUuid="${disk##*/}"
    output="$dest/$name.$volUuid.qcow2"
    if ! qemu-img convert -O qcow2 "$disk" "$output" > "$logFile" 2> >(cat >&2); then
      echo "qemu-img convert failed for $disk $output"
      cleanup
    fi
    name="datadisk"
  done
  sync

  ls -l --numeric-uid-gid $dest | awk '{print $5}'
}

delete_backup() {
  mount_operation

  rm -frv $dest
  sync
  umount $mount_point
  rmdir $mount_point
}

get_backup_stats() {
  mount_operation

  echo $mount_point
  df -P $mount_point 2>/dev/null | awk 'NR==2 {print $2, $3}'
  umount $mount_point
  rmdir $mount_point
}

mount_operation() {
  mount_point=$(mktemp -d -t csbackup.XXXXX)
  dest="$mount_point/${BACKUP_DIR}"
  if [ ${NAS_TYPE} == "cifs" ]; then
    MOUNT_OPTS="${MOUNT_OPTS},nobrl"
  fi
  mount -t ${NAS_TYPE} ${NAS_ADDRESS} ${mount_point} $([[ ! -z "${MOUNT_OPTS}" ]] && echo -o ${MOUNT_OPTS}) 2>&1 | tee -a "$logFile"
  if [ $? -eq 0 ]; then
      log -ne "Successfully mounted ${NAS_TYPE} store"
  else
      echo "Failed to mount ${NAS_TYPE} store"
      exit 1
  fi
}

cleanup() {
  local status=0

  rm -rf "$dest" || { echo "Failed to delete $dest"; status=1; }
  umount "$mount_point" || { echo "Failed to unmount $mount_point"; status=1; }
  rmdir "$mount_point" || { echo "Failed to remove mount point $mount_point"; status=1; }

  if [[ $status -ne 0 ]]; then
    echo "Backup cleanup failed"
    exit $EXIT_CLEANUP_FAILED
  fi
}

function usage {
  echo ""
  echo "Usage: $0 -o <operation> -v|--vm <domain name> -t <storage type> -s <storage address> -m <mount options> -p <backup path> -d <disks path> -q|--quiesce <true|false>"
  echo ""
  exit 1
}

while [[ $# -gt 0 ]]; do
  case $1 in
    -o|--operation)
      OP="$2"
      shift
      shift
      ;;
    -v|--vm)
      VM="$2"
      shift
      shift
      ;;
    -t|--type)
      NAS_TYPE="$2"
      shift
      shift
      ;;
    -s|--storage)
      NAS_ADDRESS="$2"
      shift
      shift
      ;;
    -m|--mount)
      MOUNT_OPTS="$2"
      shift
      shift
      ;;
    -p|--path)
      BACKUP_DIR="$2"
      shift
      shift
      ;;
    -q|--quiesce)
      QUIESCE="$2"
      shift
      shift
      ;;
    -d|--diskpaths)
      DISK_PATHS="$2"
      shift
      shift
      ;;
    -h|--help)
      usage
      shift
      ;;
    *)
      echo "Invalid option: $1"
      usage
      ;;
  esac
done

# Perform Initial sanity checks
sanity_checks

if [ "$OP" = "backup" ]; then
  STATE=$(virsh -c qemu:///system list | awk -v vm="$VM" '$2 == vm {print $3}')
  if [ -n "$STATE" ] && [ "$STATE" = "running" ]; then
    backup_running_vm
  else
    backup_stopped_vm
  fi
elif [ "$OP" = "delete" ]; then
  delete_backup
elif [ "$OP" = "stats" ]; then
  get_backup_stats
fi