#!/usr/bin/env bash

# Update a Flatcar installation on VMWare to use the latest OEM content
#
# Copyright 2020, Neil Mayhew <neil@kerith.ca>
# LICENSE: MIT

set -ex
shopt -s extglob nullglob

OEMCONTENT=oem-vmware.tgz
KEEPCONTENT=

if [ -n "$1" ]
then
  OEMCONTENT=$1
  KEEPCONTENT=yes
fi

# Cache sudo credentials
sudo true

if [ ! -f "$OEMCONTENT" ]
then
  # Fetch the release-signing public key
  KEYID=F88CFEDEFF29A5B4D9523864E25D9AED0593B34A
  KEYSERVER=keyserver.ubuntu.com
  gpg --keyserver $KEYSERVER --recv-key $KEYID

  # Download the current stable VMWare Flatcar release
  IMGNAME=flatcar_production_vmware_raw_image.bin
  wget -N https://stable.release.flatcar-linux.net/amd64-usr/current/${IMGNAME}.bz2{,.sig}
  gpg --verify ${IMGNAME}.bz2{.sig,}
  bunzip2 -k ${IMGNAME}.bz2

  # Mount the OEM image partition via loopback
  MNT=$(mktemp -d) && trap 'rmdir "$MNT"' 0
  LOOPDEV=$(sudo losetup -f --show -P ${IMGNAME})
  sudo mount -r "${LOOPDEV}p6" "$MNT"

  # Save the content
  tar -cvzf "$OEMCONTENT" --exclude=lost+found -C "$MNT" .

  # Unmount the OEM image partition
  sudo umount "$MNT"
  sudo losetup -d "${LOOPDEV}"

  # Remove the downloaded image files
  rm -f ${IMGNAME}{,.bz2{.sig,}}
fi

# Stop existing services and remove them
if [ -d /usr/share/oem/units/ ]
then
  cd /usr/share/oem/units/
  UNITS=(*)
  cd "$OLDPWD"
  sudo systemctl stop -- "${UNITS[@]}" || true
  cd /etc/systemd/system/
  sudo rm -f "${UNITS[@]}"
  cd "$OLDPWD"
  sudo systemctl daemon-reload
fi

# Remove the exiting content
sudo rm -rf /usr/share/oem/!(lost+found)

# Install the new content
sudo tar -xf "$OEMCONTENT" -C /usr/share/oem
[ -n "$KEEPCONTENT" ] || rm -f "$OEMCONTENT"

# Install new services and start them
if [ -d /usr/share/oem/units/ ]
then
  cd /usr/share/oem/units/
  UNITS=(*)
  [ "${#UNITS[@]}" -gt 0 ] &&
    sudo cp -p -- "${UNITS[@]}" /etc/systemd/system/
  cd "$OLDPWD"
  sudo systemctl daemon-reload
  sudo systemctl start -- "${UNITS[@]}"
fi

# Inform the user
set +x
echo "New OEM content was installed and services were restarted"