#!/bin/bash
# This file is part of Ian Kelling's automated-distro-installer
# Copyright (C) 2024 Ian Kelling

# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

set -eE -o pipefail
trap 'echo "$0:$LINENO:error: \"$BASH_COMMAND\" returned $?" >&2' ERR

[[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"

# default
kernel_ver='6\.6'
case $1 in
  stable)
    # note: update kernel_ver when we are ready to jump to a new stable kernel.
    # Stable kernels are listed here: https://www.kernel.org/category/releases.html
    kernel_ver='6\.6'
    ;;
  unstable)
    kernel_ver='[1-9]'
    ;;
esac


prereqs=()
for p in wget curl; do
  if ! type -p $p &>/dev/null; then
    prereqs+=($p)
  fi
done
if (( ${#prereqs[@]} >= 1 )); then
  apt-get -y install ${prereqs[@]}
fi


tmpdir=$($ROOTCMD mktemp -d) || exit
# shellcheck disable=SC2154 # defined by fai
outertmp=$target/$tmpdir
trap 'cd; rm -rf "$outertmp"' EXIT
cd $outertmp

# We get 10 versions cuz maybe the latest directory (or few) get created but not populated.
tmps=$(curl -s https://kernel.ubuntu.com/mainline/ | \
         sed -rn 's,.*alt="\[DIR\]".*href="([^/]+).*,\1,p' | \
         grep -v -- -rc | sed 's/^v//' | grep "^$kernel_ver" | sort -Vr | head -n10)
mapfile -t latest_versions <<<"$tmps"

for va in "${latest_versions[@]}"; do
  sleep .2 # be nice
  # note the wiki page about these says to install linux-headers.*generic.*amd64, but
  # as of 2024, they have a requirement of a very new glibc, and people report
  # that installing it is not needed.
  tmpstr=$(curl -s https://kernel.ubuntu.com/mainline/v$va/amd64/CHECKSUMS | awk '$2 ~ /^linux-/ { print $2 }' | sort -u | sed '/linux-headers.*generic.*amd64/d' )
  if [[ $tmpstr ]]; then
    mapfile -t pkgs <<<"$tmpstr"
    break
  fi
done

if (( ${#pkgs[@]} != 3 )); then
  echo "$0: error. expected to find 3 kernel packages, got: ${pkgs[*]}" >&2
  exit 1
fi

urls=()
for p in ${pkgs[@]}; do
  if ! $ROOTCMD dpkg -s -- "${p%%_*}"  2>&1 | grep -Fx "Status: install ok installed" &>/dev/null; then
    urls+=(https://kernel.ubuntu.com/mainline/v$va/amd64/$p)
  fi
done
if (( ${#urls[@]} >= 1 )); then
  wget -nv -- "${urls[@]}"
  $ROOTCMD dpkg -i ${pkgs[@]/#/$tmpdir/}
fi