#!/bin/zsh
use bastion --group remote
use config --group remote

DEPENDENCIES+=(timeout ssh)
#####################################################################

USAGE__options='
	-n, --name                session name to test
	-s, --connection-string   explicit session host / ssh connection string to test
	-t, --maximum-timeout     maximum connection timeout before failure (in seconds)
	-c, --command             testing command; performs echo by default

	--use-bastion   true / false override for bastion preference
	                (default: session.name.bastion.preferred or "false")
'

USAGE__description='
	Tests whether you can connect to a particular session or
	host string.
'

#####################################################################

MAIN() {
	local CONNECTION_STRING REMOTE_NAME
	local TIMEOUT_SECONDS=3
	local COMMAND='echo OK &>/dev/null'
	local USE_BASTION
	while [[ $# -gt 0 ]]
	do
		local _S=1
		case $1 in
			-n | --name )
				((_S+=1))
				REMOTE_NAME=$2
				CONNECTION_STRING=$(remote.config.get-connection-string $REMOTE_NAME)
				;;
			-s | --connection_string )
				((_S+=1))
				CONNECTION_STRING="$2"
				;;
			-t | --maximum-timout )
				((_S+=1))
				TIMEOUT_SECONDS=$2
				[[ $TIMEOUT_SECONDS -gt 0 ]] \
					|| echo.error "invalid timeout seconds '$TIMEOUT_SECONDS'"
				;;
			-c | --command )
				((_S+=1))
				COMMAND=$2
				;;
			--use-bastion )
				((_S+=1))
				USE_BASTION=$2
				case $USE_BASTION in
					true | false ) ;;
					* ) echo.error "invalid setting for '--use-bastion' (must be 'true' or 'false')" ;;
				esac
				;;
			* ) echo.error "unrecognized argument '$1'" ;;
		esac
		[[ $_S -le $# ]] \
			&& shift $_S \
			|| echo.error "missing argument for '$1'" \
			|| shift $#
	done

	[ $CONNECTION_STRING ] \
		|| echo.error "unable to determine connection string"


	[ $USE_BASTION ] || {
		USE_BASTION=$(\
			remote.config.query-connection-with-fallback \
				".sessions.$REMOTE_NAME.bastion.preferred" \
				'false' \
				;
			)
	}

	utils.check-errors --fail


	##########################################

	local BASTION_HOST
	[[ $USE_BASTION =~ true ]] && {
		BASTION_HOST=$(\
			remote.config.query-connection-with-fallback \
				".sessions.$REMOTE_NAME.bastion.session" \
			)
	}

	[[ $USE_BASTION =~ true ]] && {
		[ $BASTION_HOST ] \
			|| echo.error "cannot connect to $REMOTE_NAME; no configured bastion host" \
			|| return 1
	}

	case $CONNECTION_STRING in
		localhost | $USER@localhost )
			CONNECTION_TEST() { return 0; } # current user on local machine can always connect
			;;
		* )
			[[ $USE_BASTION =~ true ]] && {
				echo.debug "MAIN -n $BASTION_HOST -c \"$(remote.bastion.get-passthrough-prefix) remote test -- -n $REMOTE_NAME -c \"$COMMAND\"\""
				BASTION_TARGET="$REMOTE_NAME" MAIN -n $BASTION_HOST -c "$(remote.bastion.get-passthrough-prefix) remote test -- -n $REMOTE_NAME -c \"$COMMAND\""
				return $?
			}

			CONNECTION_TEST() {
				[ $REMOTE_NAME ] && {
					[[ $(remote.config.query-connection .sessions.$REMOTE_NAME.enabled) =~ false ]] && {
						return 1
					}
				}
				local REMOTE_ARGS=()
				REMOTE_ARGS+=($(remote.config.get-ssh-args --type ssh $REMOTE_NAME))
				REMOTE_ARGS+=(-o BatchMode=yes)
				echo.debug "attempting\ntimeout $TIMEOUT_SECONDS ssh $REMOTE_ARGS $CONNECTION_STRING "'\'"\"$COMMAND"'\'"\"" >&2
				timeout --foreground $TIMEOUT_SECONDS ssh ${REMOTE_ARGS[@]} "$CONNECTION_STRING" "$COMMAND" >&2
			}
			;;
	esac

	[ $REMOTE_NAME ] || REMOTE_NAME=explicit
	echo.status "testing connection $CONNECTION_STRING ($REMOTE_NAME$([ $BASTION_TARGET ] && echo " -> $BASTION_TARGET"))" \
		&& CONNECTION_TEST \
		&& echo.success "successfully connected to '$CONNECTION_STRING' ($REMOTE_NAME)" \
		|| echo.error "connection to '$CONNECTION_STRING ($REMOTE_NAME)' failed" \
}