#!/bin/sh
#
# Purpose {{{
# This script will try to manage VPN with forticlient v6
#   1. Start a VPN will
#     a. Ensure forticlient-scheduler systemd unit is started.
#     b. Try to connect to VPN with profile name.
#   2. Stop a VPN will
#     a. Disconnect from the VPN.
#     b. Stop and disable forticlient-scheduler systemd unit.
#     c. Restart systemd-resolved to ensure to have correct DNS resolvers.
#
# 2023-01-24
# }}}
# Flags {{{
## Exit on error {{{
set -o errexit
## }}}
## Exit on unset var {{{
### Use "${VARNAME-}" to test a var that may not have been set
set -o nounset
## }}}
## Pipeline command is treated as failed {{{
### Not available in POSIX sh − https://github.com/koalaman/shellcheck/wiki/SC3040
#set -o pipefail
## }}}
## Help with debugging {{{
### Call the script by prefixing it with "TRACE=1 ./script.sh"
if [ "${TRACE-0}" -eq 1 ]; then set -o xtrace; fi
## }}}
# }}}
# Vars {{{
PROGNAME=$(basename "${0}"); readonly PROGNAME
PROGDIR=$(readlink --canonicalize-missing $(dirname "${0}")); readonly PROGDIR
ARGS="${*}"; readonly ARGS
readonly NBARGS="${#}"
[ -z "${DEBUG-}" ] && DEBUG=1
## Export DEBUG for sub-script
export DEBUG

## Default values for some vars
readonly REQUEST_STATUS_DEFAULT="start"
readonly VPN_PROFILE_NAME_DEFAULT="Universite Rennes 1"
VPN_USER_DEFAULT=$(whoami) ; readonly VPN_USER_DEFAULT
readonly FORTICLIENT_NEW_VERSION="7.0.0.0"

## Colors
readonly PURPLE='\033[1;35m'
readonly RED='\033[0;31m'
readonly RESET='\033[0m'
readonly COLOR_DEBUG="${PURPLE}"
# }}}
usage() {                                                       # {{{

	cat <<- HELP
usage: $PROGNAME [-d|-h|-p|-u]

Try to easily manage VPN with forticlient.

EXAMPLES :
    - Start VPN with default profife name and default user
        ${PROGNAME}

    - Stop the VPN
        ${PROGNAME} stop

    - Start VPN with specific VPN user
        ${PROGNAME} --user my_lambda_username start

    - Start VPN with specific VPN profile name
        ${PROGNAME} --profile "My University name" start

OPTIONS :
    -d,--debug
        Enable debug messages.

    -h,--help
        Print this help message.

    -p,--profile
        Define VPN profile name to use.
        Default : ${VPN_PROFILE_NAME_DEFAULT}

    -u,--user
        Define VPN user name to use.
        Default : ${VPN_USER_DEFAULT}

For a first connection, try to start \`forticlient gui\` first to configure EMS
and to check profile name.

HELP
}
# }}}
debug_message() {                                               # {{{

	local_debug_message="${1}"

	## Print message if DEBUG is enable (=0)
	[ "${DEBUG}" -eq "0" ] && printf '\e[1;35m%-6b\e[m\n' "DEBUG − ${PROGNAME} : ${local_debug_message}"

	unset local_debug_message

	return 0
}
# }}}
error_message() {                                               # {{{

	local_error_message="${1}"
	local_error_code="${2}"

	## Print message
	printf '%b\n' "ERROR − ${PROGNAME} : ${RED}${local_error_message}${RESET}" >&2

	unset local_error_message

	exit "${local_error_code:=66}"
}
# }}}

is_command_available() {                                        # {{{

	local_command_available_cmd="${1}"
	debug_prefix="${2:-}"

	## Return False by default
	return_command_available="1"

	if [ "$(command -v ${local_command_available_cmd})" ]; then
		debug_message "${debug_prefix}is_command_available − \
${RED}${local_command_available_cmd}${COLOR_DEBUG} seems present on this host."
		return_command_available="0"
	else
		debug_message "${debug_prefix}is_command_available − \
${RED}${local_command_available_cmd}${COLOR_DEBUG} is not available on this host."
		return_command_available="1"
	fi

	unset local_command_available_cmd
	unset debug_prefix

	return "${return_command_available}"
}
# }}}
is_version_greater_than() {                                     # {{{

	first_value="${1}"
	value_to_compare="${2}"

	## Return False by default
	return_is_version_greater_than="1"

	debug_message "is_version_greater_than − \
Is first value (${first_value}) greater than the second value (${value_to_compare})."

	if printf '%s\n' "${first_value}" "${value_to_compare}" | sort --check=quiet --version-sort; then
		debug_message "is_version_greater_than − ${first_value} <= ${value_to_compare} ."
		return_is_version_greater_than="1"
	else
		debug_message "is_version_greater_than − ${first_value} > ${value_to_compare} ."
		return_is_version_greater_than="0"
	fi

	unset first_value
	unset value_to_compare

	return "${return_is_version_greater_than}"
}
# }}}

define_vars() {                                                 # {{{

	## If request_status wasn't defined (argument) {{{
	if [ -z "${request_status-}" ]; then
		## Use default value
		readonly request_status="${REQUEST_STATUS_DEFAULT}"
	fi
	## }}}
	## If vpn_profile_name wasn't defined (argument) {{{
	if [ -z "${vpn_profile_name-}" ]; then
		## Use default value
		readonly vpn_profile_name="${VPN_PROFILE_NAME_DEFAULT}"
	fi
	## }}}
	## If vpn_user wasn't defined (argument) {{{
	if [ -z "${vpn_user-}" ]; then
		## Use default value
		readonly vpn_user="${VPN_USER_DEFAULT}"
	fi
	## }}}
	## Try to get forticlient version {{{
	is_command_available "dpkg" "| " \
		&& forticlient_current_version=$(dpkg --list -- forticlient | awk '/^ii *forticlient/ {print $3}' | sed 's/.:\(.*\)-.*/\1/')
	## }}}
}
# }}}

main() {                                                        # {{{

	debug_message "--- MAIN BEGIN"

	## If forticlient command is not available {{{
	### Exit with error
	is_command_available "forticlient" "| " \
		|| error_message "forticlient is not in PATH, ensure the package is installed." 01
	## }}}

	## Define all vars
	define_vars
	debug_message "| Define vars"

	## If forticlient version is 7 or above {{{
	### Exit with error
	is_version_greater_than "${forticlient_current_version}" "${FORTICLIENT_NEW_VERSION}" \
		&& error_message "Forticlient installed version (${forticlient_current_version}) seems newest than expected (<${FORTICLIENT_NEW_VERSION}). Please see fortinet.vpn.v7.sh script instead." 02
	## }}}

	## If the VPN must be stopped {{{
	if [ "${request_status}" = "stop" ]; then
		debug_message "-- Disconnect VPN BEGIN"

		### If the VPN is still connected {{{
		forticlient_status=$(/opt/forticlient/fortivpn status | head --lines=1 | sed 's/Status: \(.*\)/\1/' || error_message "Error while requesting current VPN status." 22)
		if [ "${forticlient_status}" = "Connected" ]; then
			debug_message "| VPN is ${RED}${forticlient_status}${COLOR_DEBUG}, try to disconnect it…"
			### Try to disconnect
			/opt/forticlient/fortivpn disconnect > /dev/null \
				|| error_message "Error when disconnecting VPN." 11
		fi
		### }}}

		### Stop the systemd service {{{
		debug_message "| Try to stop and disable forticlient-scheduler.service unit"
		sudo systemctl stop forticlient-scheduler.service \
			|| error_message "Error while stopping forticlient-scheduler.service unit" 12
		### Ensure to disable it
		sudo systemctl disable forticlient-scheduler.service \
			|| error_message "Error while disabling forticlient-scheduler.service unit" 13
		### }}}

		### Ensure to restart DNS resolver {{{
		debug_message "| Try to restart systemd-resolved.service unit to have correct DNS resolvers."
		sudo systemctl restart systemd-resolved.service \
			|| error_message "Error while restart systemd-resolved.service unit" 14
		### }}}

		debug_message "-- Disconnect VPN END"
	fi
	## }}}
	## If the VPN must be started {{{
	if [ "${request_status}" = "start" ]; then
		debug_message "-- Connect VPN BEGIN"
		### If forticlient-scheduler.service unit is not started {{{
		systemd_forticlient_status=$(systemctl show --property ActiveState --value forticlient-scheduler.service || error_message "Error while requesting forticlient-scheduler.service unit status." 21)
		if [ "${systemd_forticlient_status}" != "active" ]; then
			debug_message "| Try to start forticlient-scheduler.service unit."
			sudo systemctl restart forticlient-scheduler.service \
				|| error_message "Error while (re)starting forticlient-scheduler.service unit" 22
		fi
		### }}}
		### If forticlient-scheduler.service unit is started {{{
		systemd_forticlient_status=$(systemctl show --property ActiveState --value forticlient-scheduler.service || error_message "Error while requesting forticlient-scheduler.service unit status." 21)
		if [ "${systemd_forticlient_status}" = "active" ]; then
			debug_message "| forticlient-scheduler.service unit is ${RED}started${COLOR_DEBUG}."
		fi
		### }}}

		### If the VPN is not connected {{{
		forticlient_status=$(/opt/forticlient/fortivpn status | head --lines=1 | sed 's/Status: \(.*\)/\1/' || error_message "Error while requesting current VPN status." 22)

		if [ "${forticlient_status}" = "Not Running" ]; then
			### If script was started from a launcher {{{
			if [ -n "${DISPLAY-}" ] && [ "${TERM}" = "linux" ]; then
				### Try to launch a new TERM_EMULATOR to ask the password
				"${TERM_EMULATOR}" -e /opt/forticlient/fortivpn connect "${vpn_profile_name}" --password --user="${vpn_user}" \
					|| error_message "Error when connecting to VPN profile (${vpn_profile_name})." 24
			### }}}
			### Else we consider it was started from CLI  {{{
			else
				### Try to connect
				/opt/forticlient/fortivpn connect "${vpn_profile_name}" --password --user="${vpn_user}" \
					|| error_message "Error when connecting to VPN profile (${vpn_profile_name})." 25
			fi
			### }}}
		fi
		### }}}
		### If the VPN is connected {{{
		forticlient_status=$(/opt/forticlient/fortivpn status | head --lines=1 | sed 's/Status: \(.*\)/\1/' || error_message "Error while requesting current VPN status." 22)
		if [ "${forticlient_status}" = "Connected" ]; then
			debug_message "| VPN is ${RED}${forticlient_status}${COLOR_DEBUG}."
		fi
		### }}}

		debug_message "-- Connect VPN END"
	fi
	## }}}

	debug_message "--- MAIN END"
}
# }}}

# Manage arguments                                                # {{{
# This code can't be in a function due to argument management

if [ ! "${NBARGS}" -eq "0" ]; then

	manage_arg="0"

	## If the first argument ask for help (h|help|-h|-help|-*h|-*help)
	if printf -- '%s' "${1-}" | grep --quiet --extended-regexp -- "^-*h(elp)?$"; then
		usage
		exit 0
	fi

	# Parse all argument one by one
	while printf -- '%s' "${1-}" | grep --quiet -- "."; do

	case "${1}" in
		-d|--debug )                          ## debug
			DEBUG=0
			debug_message "--- Manage argument BEGIN"
			;;
		--start|start )                       ## Define request_status to start
			## Define var
			readonly request_status="start"
			;;
		--stop|stop )                         ## Define request_status to stop
			## Define var
			readonly request_status="stop"
			;;
		-p|--profile )                        ## Define vpn_profile_name with given arg
			## Move to the next argument
			shift
			## Define var
			readonly vpn_profile_name="${1}"
			;;
		-u|--user )                           ## Define vpn_user with given arg
			## Move to the next argument
			shift
			## Define var
			readonly vpn_user="${1}"
			;;
		* )                                   ## unknow option
			printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
			printf '%b\n' "---"
			usage
			exit 1
			;;
	esac

	debug_message "| ${RED}${1}${COLOR_DEBUG} option managed."

	## Move to the next argument
	shift
	manage_arg=$((manage_arg+1))

	done

	debug_message "| ${RED}${manage_arg}${COLOR_DEBUG} argument(s) successfully managed."
else
	debug_message "| No arguments/options to manage."
fi

	debug_message "--- Manage argument END"
# }}}

main

exit 0