#!/bin/sh -e
#
# 2020 Dennis Camera (dennis.camera at 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/>.
#
# Determines the current state of the config option.
# Possible output:
#  - present: "should" option present in config file
#  - default: the "should" option is the default -> don’t know if present
#  - absent: no such option present in config file
#

joinlines() { sed -n -e H -e "\${x;s/^\\n//;s/\\n/${1:?}/g;p;}"; }
trlower() { tr '[:upper:]' '[:lower:]'; }
tolower() { printf '%s' "$*" | trlower; }

default_value() {
	sshd -T -f /dev/null -C "$(make_conn_spec)" \
	| sed -n -e 's/^'"$(tolower "${1:?}")"'[[:blank:]]\{1,\}//p'
}

make_conn_spec() {
	if test -s "${__object:?}/parameter/match"
	then
		_match_file="${__object:?}/parameter/match"
	else
		_match_file='/dev/null'
	fi

	for _kw in \
		addr=Address \
		user=User \
		host=Host \
		laddr=LocalAddress \
		lport=LocalPort \
		rdomain=RDomain
	do
		_specname=${_kw%%=*}
		_confname=$(tolower "${_kw#*=}")
		while read -r _k _v
		do
			if test "$(tolower "${_k}")" = "${_confname}"
			then
				printf '%s=%s\n' "${_specname}" "${_v}"
				continue 2
			fi
		done <"${_match_file}"

		# NOTE: Print test spec even for empty keys to suppress errors like:
		#  'Match User' in configuration but 'user' not in connection test specification.
		# except lport:
		#  Invalid port '' in test mode specification lport=
		test "${_specname}" = 'lport' || printf '%s=\n' "${_specname}"
	done \
	| joinlines ','
	unset _match_file
}

sshd_config_file=$(cat "${__object:?}/parameter/file")
state_should=$(cat "${__object:?}/parameter/state")

if test -s "${__object:?}/parameter/option"
then
	option_name=$(cat "${__object:?}/parameter/option")
else
	option_name=${__object_id:?}
fi

value_should=$(cat "${__object:?}/parameter/value" 2>/dev/null) \
|| test "${state_should}" = absent || exit 0  # param optional if --state absent

command -v sshd >/dev/null 2>&1 || {
	echo 'Cannot find sshd.' >&2
	exit 1
}

test -e "${sshd_config_file}" || {
	echo 'absent'
	exit 0
}

value_is=$(
	sshd -T -f "${sshd_config_file}" -C "$(make_conn_spec)" \
	| sed -n -e 's/^'"$(tolower "${option_name}")"'[[:blank:]]\{1,\}//p')

if printf '%s\n' "${value_is}" | {
		if test -n "${value_should}"
		then
			grep -q -x -F "${value_should}"
		else
			# if no value provided, assume "any" value
			grep -q -e .
		fi
	}
then
	if default_value "${option_name}" | grep -q -x -F "${value_is}"
	then
		# Might produce false positives for default values.
		# TODO: Manual checking should be done, but for simplicity, this case is
		#       currently ignored here.
		echo default
	else
		echo present
	fi
else
	echo absent
fi