#!/bin/sh -e
#
# 2020 Dennis Camera (dennis.camera@ssrq-sds-fds.ch)
#
# This file is part of cdist.
#
# cdist 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.
#
# cdist 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 cdist. If not, see <http://www.gnu.org/licenses/>.
#

state_should=$(cat "${__object}/parameter/state")

case $state_should
in
	(present)
		if cmp -s "${__object}/explorer/aliases" "${__object}/parameter/alias"
		then
			# all good!
			exit 0
		fi

		if test -s "${__object}/explorer/aliases"
		then
			echo "update aliases" >>"$__messages_out"
		else
			echo "add aliases" >>"$__messages_out"
		fi

		mode=1
		;;
	(absent)
		# nothing to do if no aliases found.
		test -s "${__object}/explorer/aliases" || exit 0

		echo "delete aliases" >>"$__messages_out"

		mode=0
		;;
	(*)
		printf 'Invalid --state: %s.\n' "$state_should" >&2
		printf 'Acceptable values are: present, absent.\n' >&2
		exit 1
esac

aliases_file=$(cat "${__object}/explorer/aliases_file")

test -n "${aliases_file}" || {
	echo 'Could not determine aliases file path.' >&2
	exit 1
}

# "export" variables to remote
printf 'mode=%u\n' "${mode}"
printf "aliases_file='%s'\n" "${aliases_file}"

cat <<'EOF'
test -f "${aliases_file}" || touch "${aliases_file}"

awk -F ':[ \t]*' -v mode=$mode '
function sepafter(f, def,    _) {
	# finds the separator between field $f and $(f+1)
	_ = substr($0, length($f)+1, index(substr($0, length($f)+1), $(f+1))-1)
	return _ ? _ : def
}

function write_aliases() {
	if (aliases_written) return

	# print aliases line
	printf "%s%s", ENVIRON["__object_id"], sepafter(1, ": ")
	while ((getline < aliases_should_file) > 0) {
		if (aliases_written) printf ", "
		printf "%s", $0
		aliases_written = 1
	}
	printf "\n"
	close(aliases_should_file)
}

BEGIN {
	aliases_should_file = (ENVIRON["__object"] "/parameter/alias")
}

/^[ \t]*\#/ {
	# comment line (leave alone)
	select = 0; cont = 0  # comments terminate alias lists and continuations
	print
	next
}

{
	# is this line a continuation line?
	# (the prev. line ended in a backslash or the line starts with whitespace)
	is_cont = /^[ \t]/ || cont

	# detect if the line is a line to be continued (ends with a backslash)
	cont = ($0 ~ /\\$/)
	# if it is, we drop the backslash from the line.
	if (cont) sub(/[ \t]*\\$/, "", $0)
}

is_cont {
	# we ignore the line as it has been rewritten previously or is not
	# interesting
	next
}

$1 == ENVIRON["__object_id"] {
	# "target" user -> rewrite aliases list
	select = 1
	if (mode) write_aliases()
	next
}

{
	# other user
	select = 0
	print
}

END {
	# if the last line was an alias, the separator will be reused (looks better)
	if (mode && !aliases_written)
		write_aliases()
}
' <"${aliases_file}" >"${aliases_file}.tmp" || {
	rm -f "${aliases_file}.tmp"
	echo 'Generating new aliases file failed!' >&2
	exit 1
}

if ! cmp -s "${aliases_file}" "${aliases_file}.tmp"
then
	# aliases file was modified, replace and run `newaliases`.
	mv "${aliases_file}.tmp" "${aliases_file}"

	# run newaliases if present
	command -v newaliases >/dev/null 2>&1 && newaliases || true
else
	# no modifications were made, delete the temp file.
	rm "${aliases_file}.tmp"
fi
EOF