#!/usr/bin/env bash
set -eu

BOOT="$STORAGE/$BASE.boot.img"
SYSTEM="$STORAGE/$BASE.system.img"

[ ! -f "$BOOT" ] && echo "ERROR: Virtual DSM boot-image does not exist ($BOOT)" && exit 81
[ ! -f "$SYSTEM" ] && echo "ERROR: Virtual DSM system-image does not exist ($SYSTEM)" && exit 82

DATA="${STORAGE}/data.img"

if [[ ! -f "${DATA}" ]] && [[ -f "$STORAGE/data$DISK_SIZE.img" ]]; then
  # Fallback for legacy installs
  DATA="$STORAGE/data$DISK_SIZE.img"
fi

DISK_SIZE=$(echo "${DISK_SIZE}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
DATA_SIZE=$(numfmt --from=iec "${DISK_SIZE}")

if (( DATA_SIZE < 6442450944 )); then
  echo "ERROR: Please increase DISK_SIZE to at least 6 GB." && exit 83
fi

if [ -f "${DATA}" ]; then

  OLD_SIZE=$(stat -c%s "${DATA}")

  if [ "$DATA_SIZE" -gt "$OLD_SIZE" ]; then

    echo "INFO: Resizing data disk from $OLD_SIZE to $DATA_SIZE bytes.."
           
    REQ=$((DATA_SIZE-OLD_SIZE))
      
    # Check free diskspace    
    SPACE=$(df --output=avail -B 1 "${STORAGE}" | tail -n 1)
      
    if (( REQ > SPACE )); then
      echo "ERROR: Not enough free space to resize virtual disk." && exit 84
    fi

    if ! fallocate -l "${DATA_SIZE}" "${DATA}"; then
      echo "ERROR: Could not allocate file for virtual disk." && exit 85
    fi
      
  fi

  if [ "$DATA_SIZE" -lt "$OLD_SIZE" ]; then

    echo "INFO: Shrinking existing disks is not supported yet!"
    echo "INFO: Creating backup of old drive in storage folder..."

    mv -f "${DATA}" "${DATA}.bak"

  fi
  
fi

if [ ! -f "${DATA}" ]; then

  # Check free diskspace
  SPACE=$(df --output=avail -B 1 "${STORAGE}" | tail -n 1)

  if (( DATA_SIZE > SPACE )); then
    echo "ERROR: Not enough free space to create virtual disk." && exit 86
  fi

  # Create an empty file
  if ! fallocate -l "${DATA_SIZE}" "${DATA}"; then
    rm -f "${DATA}"
    echo "ERROR: Could not allocate file for virtual disk." && exit 87
  fi

  # Check if file exists
  if [ ! -f "${DATA}" ]; then
    echo "ERROR: Virtual DSM data disk does not exist ($DATA)" && exit 88
  fi

  # Format as BTRFS filesystem
  mkfs.btrfs -q -L data -d single -m dup "${DATA}" > /dev/null

fi

AGENT="${STORAGE}/${BASE}.agent"
[ ! -f "$AGENT" ] && echo "1" > "$AGENT"
AGENT_VERSION=$(cat "${AGENT}")

if ((AGENT_VERSION < 3)); then
  echo "INFO: The installed Guest Agent is outdated, please consider updating it or do a clean install."
fi

KVM_DISK_OPTS="\
    -device virtio-scsi-pci,id=hw-synoboot,bus=pcie.0,addr=0xa \
    -drive file=${BOOT},if=none,id=drive-synoboot,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
    -device scsi-hd,bus=hw-synoboot.0,channel=0,scsi-id=0,lun=0,drive=drive-synoboot,id=synoboot0,rotation_rate=1,bootindex=1 \
    -device virtio-scsi-pci,id=hw-synosys,bus=pcie.0,addr=0xb \
    -drive file=${SYSTEM},if=none,id=drive-synosys,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
    -device scsi-hd,bus=hw-synosys.0,channel=0,scsi-id=0,lun=0,drive=drive-synosys,id=synosys0,rotation_rate=1,bootindex=2 \
    -device virtio-scsi-pci,id=hw-userdata,bus=pcie.0,addr=0xc \
    -drive file=${DATA},if=none,id=drive-userdata,format=raw,cache=none,aio=native,discard=on,detect-zeroes=on \
    -device scsi-hd,bus=hw-userdata.0,channel=0,scsi-id=0,lun=0,drive=drive-userdata,id=userdata0,rotation_rate=1,bootindex=3"