Sindbad~EG File Manager

#!/bin/sh
# shellcheck disable=SC2028
# debian's sh echo handles escapes properly

set -e

if [ "$1" = "upgrade" ]; then
  # Remove older deprecated themes alternatives. Can be removed post 22.04
  if dpkg --compare-versions "$2" lt-nl 40.1-1ubuntu1; then
    new="gdm-theme.gresource"
    old="gdm3-theme.gresource"
    link=/usr/share/gnome-shell/$new
    current=$(update-alternatives --query "$old" | awk '$1 == "Value:" {print $2}')

    case "$current" in
      /usr/share/gnome-shell/gnome-shell-theme.gresource) allowed=1 ;;
      /usr/share/gnome-shell/theme/Yaru/gnome-shell-theme.gresource) allowed=1 ;;
    esac

    if [ -z "$allowed" ] ||
       update-alternatives --query "$old" | grep -qsF "Status: manual"; then
      priority=$(update-alternatives --query "$old" | awk -v curr="$current" \
      'link == "1" { print $2; link=""; }; $0 == "Alternative: " curr { link="1" }')

      >&2 echo "WARNING: $old alternative has been set to point to $current," \
        "but it's now renamed to $new."
      >&2 echo
      >&2 echo "To re-apply the previous customization (if it supports " \
        "current version) run:"
      >&2 echo "  update-alternatives --install \\\\\n" \
        "    $link \\\\\n" \
        "    $new \\\\\n" \
        "    $current \\\\\n" \
        "    $priority\n"
      >&2 echo "Otherwise, ensure that the package providing it is updated"
    fi

    update-alternatives --remove-all "$old" || true
  fi
fi