#!/bin/bash
# I, Ian Kelling, follow the GNU license recommendations at
# https://www.gnu.org/licenses/license-recommendations.en.html. They
# recommend that small programs, < 300 lines, be licensed under the
# Apache License 2.0. This file contains or is part of one or more small
# programs. If a small program grows beyond 300 lines, I plan to switch
# its license to GPL.

# Copyright 2024 Ian Kelling

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

distro-name() {
  local x
  if [[ -f /etc/fedora-release ]]; then
    echo fedora
  elif [[ -e /etc/os-release ]]; then
    sed -rn 's/^ID=(.*)/\1/p' /etc/os-release
  elif type -p lsb_release &>/dev/null; then
    # well, this is more standard, but it's 2 ms vs 200 ms
    x=$(lsb_release -si); echo ${x,,}
  else
    echo "unknown distro"
    return 1
  fi
}

distro-name-compat() {
  local x
  x=$(distro-name)
  case $x in
    trisquel)
      echo ubuntu
      ;;
    *)
      printf "%s\n" "$x"
      ;;
  esac
}

distro-name-ver() {
  printf "%s\n" "$(distro-name)$(debian-archive)"
}

distro-num() {
  # Subshell keeps environment clean.
  ( . /etc/os-release
    # in ubuntu the .x matters, trisquel it doesnt
    if [[ $ID == ubuntu ]]; then
      echo $VERSION_ID
    else
      echo ${VERSION_ID%%.*}
    fi
  )
}

debian-archive() {
  isdeb || return 0
  local archive expression pri name highpri shortest
  local policy="${1:-$(apt-cache policy)}" || return $?
  # a = archive
  # n = codename
  # o = origin
  # c = component (licensing component)
  # l = label (Debian{,-Security,-Updates})
  local d
  d=$(distro-name)
  # goto b for archive lines we are interested in, a for lines we arent
  # print priority + archive name. priority is in
  # the previous line from the archive line.
  # case insensitive, because $d is lower and we are matching with first char upper
  read -rd '' expression <<EOF ||:
/o=$d/I!b a;/l=$d/I!b a;/c=main/!b a b b;
: a;s/^ *([-0-9]+).*/\1/;h;b;
: b;s/^.*a=([^,]+).*/ \1/;H;x;s/\n//;p
EOF
  while read -r pri name; do
    # in ubuntu, we get archives like flidas, flidas-updates, all the same pri,
    # so just pick the shortest one.
    if [[ ! $highpri ]]; then
      highpri=$pri;
      shortest=$name
      continue
    fi
    if [[ $pri != "$highpri" ]]; then
      break
    fi
    if (( ${#shortest} > ${#name} )); then
      shortest=$name
    fi
  done < <(echo "$policy" | sed -rn "$expression" | sort -rn || [[ $? == 141 ]])
  echo "$shortest"
}

# formatted for use in pfile() in package-manager-abstractions
positive-origins() {
  isdeb || return 0
  local archive expression pri name highpri shortest policy
  # In theory we might want a policy subset, we could alter this to pass
  # it in.
  policy="(apt-cache policy)"
  # a = archive
  # n = codename
  # o = origin
  # c = component (licensing component)
  # l = label (Debian{,-Security,-Updates})
  read -rd '' expression <<EOF ||:
/^ *([-0-9]+).*/{s/^ *([-0-9]+).*/\1/;h}
/^.*o=([^,]+).*/{s/^.*o=([^,]+).*/ \1/;H;x;s/\n//;p}
EOF
  origins=
  while read -r pri name; do
    if (( pri > 0 )); then
      if [[ ! $origins ]]; then
        origins=$name
      else
        origins+=,$name
      fi
    fi
  done < <(echo "$policy" | sed -rn "$expression" | sort -rn || [[ $? == 141 ]])
  echo $origins
}

isdebian-testing() {
  [[ $(debian-archive) == testing ]]
}
# I only do testing or stable.
isdebian-stable() {
  [[ $(debian-archive) == stable ]]
}

debian-codename() {
  isdeb || return 0
  local policy
  policy="$(apt-cache policy)"
  archive=$(debian-archive "$policy")
  printf "%s\n" "$policy" | sed -rn "s/^.*a=$archive,n=([a-z]+).*/\1/p;T;q" || [[ $? == 141 ]]
}
debian-codename-compat() {
  local n
  n=$(debian-codename)
  case $n in
    flidas)
      echo xenial
      ;;
    etiona)
      echo bionic
      ;;
    nabia)
      echo focal
      ;;
    aramo)
      echo jammy
      ;;
    *)
      echo $n
      ;;
  esac
}

isfedora() {
  [[ $(distro-name) == fedora ]]
}
isdebian() {
  [[ $(distro-name) == debian ]]
}
isarch() {
  [[ $(distro-name) == arch ]]
}
isubuntu() {
  [[ $(distro-name) == ubuntu ]]
}
istrisquel() {
  [[ $(distro-name) == trisquel ]]
}
# is debian/apt based
isdeb() { command -v apt-get &>/dev/null; }