#!/bin/sh

set -eu
apt_opt=
if [ $# -eq 0 ]; then
	: # interactive
elif [ "${1:-}" = "-y" ]; then
	apt_opt="-y"
	shift
fi

obsolete_kernels() {
	local current= latest=
	local v= p=

	if [ $# -gt 2 ]; then
		current="$1" latest="$2"
		shift 2
		for v; do
			COLUMNS=500 dpkg -l "linux*$v*" | sed -n -e 's|^..  \(linux[^ \]\+\)[ \t].*|\1|p'
		done | while read p; do
			case "$p" in
			*-$current|*-$current-*|*-$latest|*-$latest-*)
				echo "$p: SKIP" >&2
				;;
			*)
				printf "$p "
				;;
			esac
		done

	fi
}

remove=$(obsolete_kernels \
		"$(uname -r | sed -e 's|-generic$||')" \
		$(ls -1 /boot/vmlinuz-* | \
			sed -e 's|^/boot/vmlinuz-||' -e 's|\.efi\.signed$||' -e 's|-generic$||' | \
			sort -urV))

aptget="apt-get${apt_opt:+ $apt_opt}"

cmd="$aptget update"
if [ -n "$remove" ]; then
	cmd="$cmd && dpkg -P $remove"
fi
cmd="$cmd && $aptget autoremove --purge"
cmd="$cmd && $aptget upgrade && $aptget dist-upgrade"
set -x
exec sudo sh -c "$cmd"