post_install() {
  assert_user_and_group_exist

  chown -R neo4j.neo4j /var/lib/neo4j
  chown -R neo4j.neo4j /var/log/neo4j
  chown -R neo4j.neo4j /etc/neo4j

  /usr/bin/systemd-tmpfiles --create neo4j.conf

  warn_about_java_home
}

post_upgrade() {
  assert_user_and_group_exist
  warn_about_java_home
}

post_remove() {
  if getent passwd neo4j >/dev/null; then
    userdel neo4j
  fi
  if getent group neo4j >/dev/null; then
    groupdel neo4j
  fi
}

assert_user_and_group_exist() {
  if ! getent group neo4j >/dev/null; then
    groupadd --system neo4j
  fi
  if ! getent passwd neo4j >/dev/null; then
    useradd --system -g neo4j -d /var/lib/neo4j -s /bin/false neo4j
  fi
}

warn_about_java_home() {
  echo "------------------------------"
  echo "--- ACHTUNG ACHTUNG ALARM! ---"
  echo "------------------------------"
  echo "Before starting the Neo4j service, create this file"
  echo ""
  echo "/etc/systemd/system/neo4j.service.d/java_home.conf"
  echo ""
  echo "with the following content:"
  echo ""
  echo "[Service]"
  echo "Environment=JAVA_HOME=/your/java/home/path"
  echo ""
  echo "changing '/your/java/home/path' to your actual JAVA_HOME path."
}