#!/usr/bin/env bash
export LC_ALL=C

function disk_delete() {
  if [ -e "${disk_img}" ]; then
    rm "${disk_img}"
    echo "SUCCESS! Deleted ${disk_img}"
  else
    echo "NOTE! ${disk_img} not found. Doing nothing."
  fi
}

function snapshot_apply() {
  local TAG="${1}"
  if [ -z "${TAG}" ]; then
    echo "ERROR! No snapshot tag provided."
    exit
  fi

  if [ -e "${disk_img}" ]; then
    ${QEMU_IMG} snapshot -q -a "${TAG}" "${disk_img}"
    if [ $? -eq 0 ]; then
      echo "SUCCESS! Applied snapshot ${TAG} to ${disk_img}"
    else
      echo "ERROR! Failed to apply snapshot ${TAG} to ${disk_img}"
    fi
  else
    echo "NOTE! ${disk_img} not found. Doing nothing."
  fi
}

function snapshot_create() {
  local TAG="${1}"
  if [ -z "${TAG}" ]; then
    echo "ERROR! No snapshot tag provided."
    exit
  fi

  if [ -e "${disk_img}" ]; then
    ${QEMU_IMG} snapshot -q -c "${TAG}" "${disk_img}"
    if [ $? -eq 0 ]; then
      echo "SUCCESS! Created snapshot ${TAG} of ${disk_img}"
    else
      echo "ERROR! Failed to create snapshot ${TAG} of ${disk_img}"
    fi
  else
    echo "NOTE! ${disk_img} not found. Doing nothing."
  fi
}

function snapshot_delete() {
  local TAG="${1}"
  if [ -z "${TAG}" ]; then
    echo "ERROR! No snapshot tag provided."
    exit
  fi

  if [ -e "${disk_img}" ]; then
    ${QEMU_IMG} snapshot -q -d "${TAG}" "${disk_img}"
    if [ $? -eq 0 ]; then
      echo "SUCCESS! Deleted snapshot ${TAG} of ${disk_img}"
    else
      echo "ERROR! Failed to delete snapshot ${TAG} of ${disk_img}"
    fi
  else
    echo "NOTE! ${disk_img} not found. Doing nothing."
  fi
}

function snapshot_info() {
  if [ -e "${disk_img}" ]; then
    ${QEMU_IMG} info "${disk_img}"
  fi
}

function get_port() {
    local PORT_START=22220
    local PORT_RANGE=9
    while true; do
        local CANDIDATE=$[${PORT_START} + (${RANDOM} % ${PORT_RANGE})]
        (echo "" >/dev/tcp/127.0.0.1/${CANDIDATE}) >/dev/null 2>&1
        if [ $? -ne 0 ]; then
            echo "${CANDIDATE}"
            break
        fi
    done
}

function vm_boot() {
  local VMNAME=$(basename ${VM} .conf)
  local VMDIR=$(dirname ${disk_img})
  local BIOS=""
  local VIDEO_DRV=""
  local GL="on"
  local VIRGL="on"
  local OUTPUT="sdl"
  local QEMU_VER=$(${QEMU} -version | head -n1 | cut -d' ' -f4 | cut -d'(' -f1)
  echo "Starting ${VM}"
  echo " - QEMU:     ${QEMU} v${QEMU_VER}"

  if [ ${ENABLE_EFI} -eq 1 ]; then
    if [ -e "${VIRGIL_PATH}/usr/share/qemu/edk2-x86_64-code.fd" ] ; then
      if [ ! -e "${VMDIR}/${VMNAME}-vars.fd" ]; then
        cp "${VIRGIL_PATH}/usr/share/qemu/edk2-i386-vars.fd" "${VMDIR}/${VMNAME}-vars.fd"
      fi
      BIOS="-drive if=pflash,format=raw,readonly,file=${VIRGIL_PATH}/usr/share/qemu/edk2-x86_64-code.fd -drive if=pflash,format=raw,file=${VMDIR}/${VMNAME}-vars.fd"
    else
      echo " - EFI:      Booting requested but no EFI firmware found."
      echo "             Booting from Legacy BIOS."
    fi
    echo " - BIOS:     EFI"
  else
    echo " - BIOS:     Legacy"
  fi

  # Force to lowercase.
  guest_os=$(echo ${guest_os,,})
  # Make any OS specific adjustments
  case ${guest_os} in
    linux)
      VIDEO_DRV="virtio-vga"
      ;;
    windows)
      VIDEO_DRV="qxl"
      ;;
    *)
      echo "ERROR! Unrecognised guest OS: ${guest_os}"
      exit
      ;;
  esac
  echo " - Guest:    ${guest_os^} optimised."

  echo " - Disk:     ${disk_img} (${disk})"
  if [ ! -f "${disk_img}" ]; then
      # If there is no disk image, create a new image.
      ${QEMU_IMG} create -q -f qcow2 "${disk_img}" "${disk}"
      if [ -z "${iso}" ]; then
        echo "ERROR! You haven't specified a .iso image to boot from."
        exit 1
      fi
      echo "             Just created, booting from ${iso}"
    if [ $? -ne 0 ]; then
      echo "ERROR! Failed to create ${disk_img} of ${disk}. Stopping here."
      exit 1
    fi
  elif [ -e ${disk_img} ]; then
    # Check there isn't already a process attached to the disk image.
    QEMU_LOCK_TEST=$(${QEMU_IMG} info ${disk_img} 2>/dev/null)
    if [ $? -ne 0 ]; then
      echo "             Failed to get "write" lock. Is another process using the disk?"
      exit 1
    else
      DISK_CURR_SIZE=$(stat -c%s "${disk_img}")
      if [ ${DISK_CURR_SIZE} -le ${DISK_MIN_SIZE} ]; then
        echo "             Looks unused, booting from ${iso}"
        if [ -z "${iso}" ]; then
          echo "ERROR! You haven't specified a .iso image to boot from."
          exit 1
        fi
      else
        # If there is a disk image, that appears to have an install
        # then do not boot from the iso
        iso=""
      fi
    fi
  fi

  # Has the status quo been requested?
  if [ "${STATUS_QUO}" == "-snapshot" ] &&  [ -z "${iso}" ]; then
    echo "             Existing disk state will be preserved, no writes will be committed."
  fi

  if [ -n "${iso}" ] && [ -e "${iso}" ]; then
    local ISO_BOOT="-drive media=cdrom,file="${iso}",index=2"
    echo " - Boot:     ${iso}"
  fi

  if [ -n "${driver_iso}" ] && [ -e "${driver_iso}" ]; then
    local ISO_DRIVER="-drive media=cdrom,file="${driver_iso}",index=3"
    echo " - Drivers:  ${driver_iso}"
  fi

  local CORES_VM="1"
  local CORES_HOST=$(nproc --all)
  if [ ${CORES_HOST} -ge 8 ]; then
    CORES_VM="4"
  elif [ ${CORES_HOST} -ge 4 ]; then
    CORES_VM="2"
  fi
  echo " - CPU:      ${CORES_VM} Core(s)"

  local RAM_VM="2G"
  local RAM_HOST=$(free --mega -h | grep Mem | cut -d':' -f2 | cut -d'G' -f1 | sed 's/ //g')
  if [ ${RAM_HOST} -ge 64 ]; then
    RAM_VM="4G"
  elif [ ${RAM_HOST} -ge 16 ]; then
    RAM_VM="3G"
  fi
  echo " - RAM:      ${RAM_VM}"

  local X_RES=1152
  local Y_RES=648
  if [ "${XDG_SESSION_TYPE}" == "x11" ]; then
    local LOWEST_WIDTH=$(xrandr --listmonitors | grep -v Monitors | cut -d' ' -f4 | cut -d'/' -f1 | sort | head -n1)
    if [ ${LOWEST_WIDTH} -ge 3840 ]; then
      X_RES=3200
      Y_RES=1800
    elif [ ${LOWEST_WIDTH} -ge 2560 ]; then
      X_RES=2048
      Y_RES=1152
    elif [ ${LOWEST_WIDTH} -ge 1920 ]; then
      X_RES=1664
      Y_RES=936
    elif [ ${LOWEST_WIDTH} -ge 1280 ]; then
      X_RES=1152
      Y_RES=648
    fi
  fi

  # GL is not working with GTK currently
  if [ "${OUTPUT}" == "gtk" ]; then
    GL="off"
  else
    echo " - Screen:   ${X_RES}x${Y_RES}"
  fi
  
  if [ "${VIDEO_DRV}" == "qxl" ]; then
    echo " - Video:    ${VIDEO_DRV^^}"
    local VIDEO_DEV=" -vga ${VIDEO_DRV}"
    VIRGL="off"
  else
    echo " - Video:    ${VIDEO_DRV^^[v,g,a]}"
    local VIDEO_DEV="-device ${VIDEO_DRV},virgl=${VIRGL},xres=${X_RES},yres=${Y_RES}"
  fi
  echo " - GL:       ${GL^^}"
  echo " - Virgil3D: ${VIRGL^^}"
  echo " - Display:  ${OUTPUT^^}"

  # Set the hostname of the VM
  local NET="user,hostname=${VMNAME}"

  # If smbd is available, export $HOME to the guest via samba
  if [ -e "${VIRGIL_PATH}/usr/sbin/smbd" ]; then
      NET="${NET},smb=${HOME}"
  fi

  if [[ ${NET} == *"smb"* ]]; then
    echo " - smbd:     ${HOME} will be exported to the guest via smb://10.0.2.4/qemu"
  else
    echo " - smbd:     ${HOME} will not be exported to the guest. 'smbd' not found."
  fi

  # Find a free port to expose ssh to the guest
  local PORT=$(get_port)
  if [ -n "${PORT}" ]; then
    NET="${NET},hostfwd=tcp::${PORT}-:22"
    echo " - ssh:      ${PORT}/tcp is connected. Login via 'ssh user@localhost -p ${PORT}'"
  else
    echo " - ssh:      All ports for exposing ssh have been exhausted."
  fi

  # Boot the iso image
  ${QEMU} -name ${VMNAME},process=${VMNAME} \
    ${BIOS} \
    -drive id=disk,file=${disk_img},format=qcow2,if=virtio,aio=native,cache.direct=on \
    ${ISO_BOOT} ${ISO_DRIVER} \
    -enable-kvm \
    -machine q35,accel=kvm \
    -cpu host,kvm=on \
    -smp ${CORES_VM} \
    -m ${RAM_VM} \
    -device virtio-balloon \
    -netdev ${NET},id=nic \
    -device virtio-net,netdev=nic \
    -rtc base=localtime,clock=host \
    -serial mon:stdio \
    -audiodev pa,id=pa,server=unix:${XDG_RUNTIME_DIR}/pulse/native,out.stream-name=${LAUNCHER}-${VMNAME},in.stream-name=${LAUNCHER}-${VMNAME} \
    -device intel-hda -device hda-duplex,audiodev=pa \
    -device qemu-xhci,id=xhci,p2=8,p3=8 -device usb-kbd -device usb-tablet \
    -object rng-random,id=rng0,filename=/dev/urandom \
    -device virtio-rng-pci,rng=rng0 \
    ${VIDEO_DEV} \
    -display ${OUTPUT},gl=${GL} \
    ${STATUS_QUO} \
    "$@"
}

function usage() {
  echo
  echo "Usage"
  echo "  ${LAUNCHER} --vm ubuntu.conf"
  echo
  echo "You can also pass optional parameters"
  echo "  --delete                : Delete the disk image."
  echo "  --efi                   : Enable EFI BIOS."
  echo "  --snapshot apply <tag>  : Apply/restore a snapshot."
  echo "  --snapshot create <tag> : Create a snapshot."
  echo "  --snapshot delete <tag> : Delete a snapshot."
  echo "  --snapshot info         : Show disk/snapshot info."
  echo "  --status-quo            : Do not commit any changes to disk/snapshot."
  exit 1
}

# Lowercase variables are used in the VM config file only
guest_os="linux"
iso=""
driver_iso=""
disk_img=""
disk="64G"

DELETE=0
ENABLE_EFI=0
SNAPSHOT_ACTION=""
SNAPSHOT_TAG=""
STATUS_QUO=""
VM=""

readonly LAUNCHER=$(basename $0)
readonly DISK_MIN_SIZE=$((197632 * 8))
readonly QEMU="/snap/bin/qemu-virgil"
readonly QEMU_IMG="/snap/bin/qemu-virgil.qemu-img"
readonly VIRGIL_PATH="/snap/qemu-virgil/current"

while [ $# -gt 0 ]; do
  case "${1}" in
    -efi|--efi)
      ENABLE_EFI=1
      shift;;
    -delete|--delete)
      DELETE=1
      shift;;
    -snapshot|--snapshot)
      SNAPSHOT_ACTION="${2}"
      if [ -z "${SNAPSHOT_ACTION}" ]; then
        echo "ERROR! No snapshot action provided."
        exit 1
      fi
      shift
      SNAPSHOT_TAG="${2}"
      if [ -z "${SNAPSHOT_TAG}" ] && [ "${SNAPSHOT_ACTION}" != "info" ]; then
        echo "ERROR! No snapshot tag provided."
        exit 1
      fi
      shift
      shift;;
    -status-quo|--status-quo)
      STATUS_QUO="-snapshot"
      shift;;
    -vm|--vm)
      VM="$2"
      shift
      shift;;
    -h|--h|-help|--help)
      usage;;
    *)
      echo "ERROR! \"${1}\" is not a supported parameter."
      usage;;
  esac
done

# Check we have qemu-virgil available
if [ ! -e "${QEMU}" ] && [ ! -e "${QEMU_IMG}" ]; then
  echo "ERROR! qemu-virgil not found. Please install the qemu-virgil snap."
  echo "       https://snapcraft.io/qemu-virgil"
  exit 1
fi

if [ -n "${VM}" ] && [ -e "${VM}" ]; then
  source "${VM}"
  if [ -z "${disk_img}" ]; then
    echo "ERROR! No disk_img defined."
    exit 1
  fi
else
  echo "ERROR! Virtual machine configuration not found."
  usage
fi

if [ ${DELETE} -eq 1 ]; then
  disk_delete
  exit
fi

if [ -n "${SNAPSHOT_ACTION}" ]; then
  case ${SNAPSHOT_ACTION} in
    apply)
      snapshot_apply "${SNAPSHOT_TAG}"
      snapshot_info
      exit;;
    create)
      snapshot_create "${SNAPSHOT_TAG}"
      snapshot_info
      exit;;
    delete)
      snapshot_delete "${SNAPSHOT_TAG}"
      snapshot_info
      exit;;
    info)
      snapshot_info
      exit;;
    *)
      echo "ERROR! \"${SNAPSHOT_ACTION}\" is not a supported snapshot action."
      usage;;
  esac
fi

vm_boot