#!/bin/bash
# simple helper, mainly for testing the provided Systemd units.

set -eu
export LC_ALL=C

: ${EXIM=exim}
: ${EXIM_LOGDIR=/var/log/exim}
: ${EXIM_SPOOLDIR=/var/spool/exim}

# Packagers should install to $(systemd-path systemd-system-unit)
# which mostly is something like /lib/systemd/system
dstdir=

usage="$0 [OPTIONS] variant...
  This simple script installs Systemd unit files to the desired destination, replacing
  the {{Placeholder}}s.

  VARIANT: one of daemon, inet, socket, maintainance, queuerunner

  OPTIONS:
  --help          print this help and exit cleanly
  --uninstall|-u  uninstall the installed files
  --dstdir|-d DIR the destination directory (mandatory, use 'DEFAULT'
                  to use Systemd's default location (`systemd-path systemd-system-conf`)

  Placeholders:
  {{exim}} from \$EXIM ($EXIM)
  {{logdir}} from \$EXIM_LOGDIR ($EXIM_LOGDIR)
  {{spooldir}} from \$EXIM_SPOOLDIR ($EXIM_SPOOLDIR)
"


tmp=$(getopt -n $0 -o d:n --long dstdir:,help,uninstall -- "$@")
eval set -- "$tmp"
while true
do
	o=$1; shift
	case $o in
                -d|--dstdir) dstdir=$1; shift;;
                --help) echo "$usage"; exit;;
		-n|--uninstall) uninstall=1;;
		--) break
	esac
done

if [[ -v uninstall ]]
then
	if ! [[ -r .installed ]]
	then
		echo "$0: noting to uninstall (.installed is empty or isn't readable)" >&2
		exit
	fi

	rm -vf $(<.installed)
	rm -f .installed
	exit
fi

case $dstdir in
        DEFAULT) dstdir=$(systemd-path systemd-system-conf);;
        "") echo "$0: --dstdir is mandatory" >&2; exit 1;;
        *) ;;
esac

if (( $# == 0 ))
then echo "$0: need variant" >&2; exit 1;
fi

function xform() {
        sed -e "s|{{exim}}|${EXIM:?}|g" \
            -e "s|{{logdir}}|${EXIM_LOGDIR:?}|g" \
            -e "s|{{spooldir}}|${EXIM_SPOOLDIR:?}|g"
}

for dir in ${@:?need source dir(s)}
do
		echo "# $dir"
		for src in "$dir"/*
		do
			dst="$dstdir/${src##*/}"
			echo "installing $dst"
			xform <"$src" >"$dst"
			echo $dst >> .installed
		done
done

if [[ $dstdir == $(systemd-path systemd-system-conf) ]]
then
        echo "# reloading systemd configuration"
        systemctl daemon-reload
fi