#!/bin/sh

# Tell apt which PostgreSQL versions have clusters present

set -eu

APTCONFDIR="/etc/apt/apt.conf.d"
[ -d "$APTCONFDIR" ] || exit 0 # skip generation on RPM systems
APTCONF="$APTCONFDIR/02autoremove-postgresql"
TMPCONF="$(mktemp --tmpdir pg_updateaptconfig.XXXXXX)"
trap "rm -f $TMPCONF" EXIT

cat > $TMPCONF <<EOF
// DO NOT EDIT!
// File maintained by /usr/share/postgresql-common/pg_updateaptconfig.
//
// Mark all PostgreSQL packages as NeverAutoRemove for which PostgreSQL
// clusters exist. This is especially important when the "postgresql" meta
// package changes its dependencies to a new version, which might otherwise
// trigger the old postgresql-NN package to be automatically removed, rendering
// the old database cluster inaccessible.

APT
{
  NeverAutoRemove
  {
EOF

pg_lsclusters -h | cut -d ' ' -f 1 | uniq | while read version; do
    echo "    \"^postgresql.*-$version\";" >> $TMPCONF
done

cat >> $TMPCONF <<EOF
  };
};
EOF

if ! cmp --silent $TMPCONF $APTCONF; then
    cp $TMPCONF $APTCONF
    chmod 444 $APTCONF
fi