#!/bin/sh -e
#
# 2020-2021 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/>.
#

INTERFACES_FILE=/etc/network/interfaces
INTERFACES_D_PATH=/etc/network/interfaces.d

os=$(cat "${__global}/explorer/os")

if test -s "${__object}/parameter/name"
then
	name=$(cat "${__object}/parameter/name")
else
	name=$__object_id
fi
onchange_action=$(cat "${__object}/parameter/onchange")
state=$(cat "${__object}/parameter/state")

# NOTE: No file ending is used not to break the source-directory stanza
#       (if used and at least for normal interface names)
iface_file="${INTERFACES_D_PATH}/${__object_id}"

onchange_action() {
	case $onchange_action
	in
		(refresh)
			printf "ifdown --force '%s' ; ifup '%s'\n" "${name}" "${name}"
			;;
		(up)
			printf "ifup '%s'\n" "${name}"
			;;
		(down)
			printf "ifdown --force '%s'\n" "${name}"
			;;
		(leave)
			# ignore
			;;
		(*)
			printf 'Invalid --onchange: %s\n' "${onchange_action}" >&2
			exit 1
			;;
	esac
}


case $os
in
	(debian)
		os_major=$(grep -o '^[0-9][0-9]*' "${__global}/explorer/os_version")
		if test "${os_major}" -lt 7
		then
			# Old versions do not support "source"
			printf 'Debian versions older than 7 (wheezy) are not supported by this type (%s)\n' "${__type##*/}" >&2
			exit 1
		fi

		if test "${state}" = 'present'
		then
			__package ifupdown --state present
			export require=__package/ifupdown
		fi
		;;
	(devuan)
		if test "${state}" = 'present'
		then
			__package ifupdown --state present
			export require=__package/ifupdown
		fi
		;;
	(*)
		printf 'Your operating system (%s) is currently not supported by this type (%s)\n' "$os" "${__type##*/}" >&2
		printf "Please contribute an implementation for it if you can.\n" >&2
		exit 1
		;;
esac

case $state
in
	(present)
		if test "${IFUPDOWND_LEAVE_EXISTING_CONFIG:-0}" -eq 0
		then
			# The /etc/network/interfaces file is overwritten with a basic example.
			__file "${INTERFACES_FILE}" --state present --owner root --mode 0644 \
				--source "${__type}/files/interfaces"
			export require="__file${INTERFACES_FILE}"
		else
			# If state is present and IFUPDOWND_LEAVE_EXISTING_CONFIG is set,
			# ensure that the interfaces.d directory is sourced in the main
			# interfaces file, being as minimally invasive as possible.
			__line "${INTERFACES_FILE}:source_interfaces.d" --state present \
				--file "${INTERFACES_FILE}" \
				--before '^#?[:blank:]*(auto|no-auto-down|no-scripts|allow-|iface|mapping|rename|source|source-directory)|^#[[:blank:]]*The .* interface$' \
				--line "source ${INTERFACES_D_PATH}/*"
			export require="__line${INTERFACES_FILE}:source_interfaces.d"
		fi

		__directory "${INTERFACES_D_PATH}" --state pre-exists \
			--owner root --mode 0755
		export require="__directory/${INTERFACES_D_PATH}"

		# Construct interface config file
		(
			cat <<-EOF
			# Managed by cdist (${__type##*/})
			# Do not change. Changes will be overwritten.

			EOF

			if test -s "${__object}/parameter/comment"
			then
				# Prefix lines with # and append trailing empty line.
				# shellcheck disable=SC2016
				{
					if test "$(cat "${__object}/parameter/comment")" = '-'
					then
						cat "${__object}/stdin"
					else
						cat "${__object}/parameter/comment"
					fi
				} | sed -e 's/^/# /;$G'
			fi

			# Put together rename line
			if test -s "${__object}/parameter/rename"
			then
				printf 'rename %s\n' "$(cat "${__object}/parameter/rename")"
			fi

			# Put together the "allow" lines (these are the line(s) usually
			# preceeding the iface line in the config).
			if test -f "${__object}/parameter/auto"
			then
				printf 'auto %s\n' "${name}"
			fi
			if test -f "${__object}/parameter/hotplug"
			then
				printf 'allow-hotplug %s\n' "${name}"
			fi
			if test -f "${__object}/parameter/no-auto-down"
			then
				printf 'no-auto-down %s\n' "${name}"
			fi
			if test -f "${__object}/parameter/no-scripts"
			then
				printf 'no-scripts %s\n' "${name}"
			fi

			addrfam=$(cat "${__object}/parameter/family")
			method=$(cat "${__object}/parameter/method")
			printf 'iface %s %s %s\n' "${name}" "${addrfam}" "${method}"

			while read -r _opt
			do
				printf '\t%s\n' "${_opt}"
			done <"${__object}/parameter/option"
			unset _opt
		) | __file "${iface_file}" --state present --owner root --mode 0644 \
			    --onchange "$(onchange_action)" --source -
		;;
	(absent)
		__file "${iface_file}" --state absent \
			--onchange "$(onchange_action)"
		;;
	(*)
		printf 'Invalid --state: %s\n' "${state}" >&2
		exit 1
		;;
esac