#! /bin/bash

# Copyright 2021-2022 Alexandre Oliva <lxoliva@fsfla.org>
#
# This program is part of GNU Linux-libre, a GNU project that
# publishes scripts to clean up Linux so as to make it suitable for
# use in the GNU Project and in Free System Distributions.
#
# 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 3 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 St, Fifth Floor, Boston, MA 02110-1301
# USA

if test -d $reldir/$rel; then
  echo $reldir/$rel exists >&2
  continue
fi

rup=$(echo "$rel" | sed 's,-gnu[0-9]*$,,')
cbr=$(echo "$rup" | sed 's,\(\.\|-rc\)[0-9]*$,,')

if test -h $reldir/LATEST-$cbr.0; then
  prev0=$(readlink $reldir/LATEST-$cbr.0)
  prevn=$(readlink $reldir/LATEST-$cbr.N)
elif test -h $reldir/LATEST-$rup.N; then
  cbr=$rup
  prev0=$(readlink $reldir/LATEST-$cbr.0)
  prevn=$(readlink $reldir/LATEST-$cbr.N)
else
  case $rup in
  [3-9].0-rc* | [1-9][0-9].0-rc*)
    prevbase=$(echo "$cbr" | sed 's,\.[0-9]*$,,')
    if test -h $reldir/LATEST-$prevbase.N; then
      prev0=$(readlink $reldir/LATEST-$prevbase.N)
      prevn=$prev0
    elif pbase=$(expr "$prevbase" - 1) && test -h $reldir/LATEST-$pbase.N; then
      prevbase=$pbase
      prev0=$(readlink $reldir/LATEST-$prevbase.N)
      prevn=$prev0
    else
      echo neither $reldir/LATEST-$prevbase.N nor $reldir/LATEST-$pbase.N exist>&2
      exit 1
    fi
    ;;
  *-rc*)
    prevbase=$(echo "$cbr" | sed 's,\.[0-9]*$,,')
    if test -h $reldir/LATEST-$prevbase.N; then
      prev0=$(readlink $reldir/LATEST-$prevbase.N)
      prevn=$prev0
    else
      echo $reldir/LATEST-$prevbase.N does not exit >&2
      exit 1
    fi
    ;;
  *)
    echo Neither $reldir/LATEST-$cbr.0 nor $reldir/LATEST-$rup.N exist >&2
    exit 1
    ;;
  esac
fi