###################################################################
#
#		This script is a part of the pam_script_auth script
#		and is not stand-alone!
#
#		It will try to mount the common shares specified in the
#		variables of the global slx config '/opt/openslx/config'.
#		An arbitrary number of shares may be given. Every share
#		requires following bundle of variables:
#
#
#		SLX_SHARE_<id>_AUTH_TYPE		[guest|user|pam]
#		SLX_SHARE_<id>_AUTH_USER		<username>
#		SLX_SHARE_<id>_AUTH_PASS		<password>
#		SLX_SHARE_<id>_PERM				[ro|rw]
#		SLX_SHARE_<id>_PATH				<path_to_share>
#
#		Note: <id> is the identifier of the share.
#
#		Example:
#			SLX_SHARE_0_PATH='//windows.server/sharename'
#			SLX_SHARE_0_AUTH_TYPE='user'
#			SLX_SHARE_0_AUTH_USER='shareuser'
#			SLX_SHARE_0_AUTH_PASS='sharepass'
#			SLX_SHARE_0_PERM='rw'
#
#		Note:	If AUTH_TYPE is set to 'pam' or 'guest', then
#				there is no need to specify AUTH_USER or AUTH_PASS
#				as it is obviously not needed.
#
###################################################################
#
# Internal helper function to mount a share
# usage: mount_share <auth_type> <auth_user> <auth_password> <permissions> <path> <share_number>
mount_share() {
	# since we are (hopefully) the only one using this function, we know we need excatly 6 args
	[ $# -ne 6 ] && { slxlog "pam-share-args" "Wrong number of arguments given! Need 6, $# given."; return; }

	# lets check if we have our variables
	local SHARE_AUTH_TYPE="$1"
	local SHARE_AUTH_USER="$2"
	local SHARE_AUTH_PASS="$3"
	local SHARE_PERM="$4"
	local SHARE_PATH="$5"
	local SHARE_NUM="$6"

	# unless specified otherwise, mount the share read-only
	[ "x${SHARE_PERM}" != "xrw" ] && SHARE_PERM='ro'

	# all good: now we can mount depending on the type
	# supports: cifs?/nfs?
	if [ "${SHARE_PATH:0:2}" = "//" ]; then
		# '//' prefixed, assume windows share
		# prepare common mount options for either authentication type
		MOUNT_OPTS="-t cifs -o nounix,uid=${USER_UID},gid=${USER_GID},forceuid,forcegid,nobrl,noacl,$SHARE_PERM"

		# now construct the mount options depending on the type of the share.
		if [ "${SHARE_AUTH_TYPE}" = "guest" ]; then
			MOUNT_OPTS="${MOUNT_OPTS},guest,file_mode=0777,dir_mode=0777"
		elif [ "${SHARE_AUTH_TYPE}" = "pam" ]; then
			export USER="${PAM_USER}"
			export PASSWD="${PAM_AUTHTOK}"
			MOUNT_OPTS="${MOUNT_OPTS},sec=ntlm,file_mode=0700,dir_mode=0700"
		elif [ "${SHARE_AUTH_TYPE}" = "user" ]; then
			# check if credentials are set
			[ ! -z "${SHARE_AUTH_USER}" ] || \
				{ slxlog "pam-share-noauthuser" "Share${SHARE_NUM}: No variable 'SLX_SHARE_${SHARE_NUM}_AUTH_USER' found in config!"; return; }
			# now export them to the env
			export USER="${SHARE_AUTH_USER}"
			export PASSWD="${SHARE_AUTH_PASS}"
			MOUNT_OPTS="${MOUNT_OPTS},sec=ntlm,file_mode=0700,dir_mode=0700"
		else
			slxlog "pam-share-auth" "Share${SHARE_NUM}: Auth type '${SHARE_AUTH_TYPE}' not supported."
			return;
		fi
	else
		# for now assume NFS-Share, start build options string with default options for all shares
		MOUNT_OPTS="-t nfs -o async,nolock"

		# TODO: here we will have to evaluate options of NFS-shares

		# unless specified otherwise, mount the share read-only
		[ "x${SHARE_PERM}" != "xrw" ] && SHARE_PERM='ro'
		MOUNT_OPTS="${MOUNT_OPTS},${SHARE_PERM}"
	fi

	############################################################################
	#
	#  Following code is independent of the type of share.
	#  The variable MOUNT_OPTS should have been set correctly
	#  up to this point.
	#
	############################################################################

	# we just mount it to the directory with the same name as the
	# last directory in the path name of the share
	# e.g. //windows.net/lehrpool -> ${COMMON_SHARE_MOUNT_POINT}/lehrpool
	local TARGET_DIR="${COMMON_SHARE_MOUNT_POINT}/$(basename ${SHARE_PATH})"
	# it exists, so let's create ${COMMON_SHARE_MOUNT_POINT}/lehrpool_${SHARE_NUM}
	[ -d "${TARGET_DIR}" ] && TARGET_DIR="${TARGET_DIR}_${SHARE_NUM}"

	# at this point is TARGET_DIR pointing to the right directory.
	mkdir -p "${TARGET_DIR}" || \
	{ slxlog "pam-share-mkdirfail" "Share${SHARE_NUM}: Could not create directory '${TARGET_DIR}'. Skipping share."; return; }

	# flag for failure
	SIGNAL=$(mktemp)
	rm -f -- "${SIGNAL}"
	# output of command
	MOUNT_OUTPUT=$(mktemp)
	# now try to mount it
	( mount ${MOUNT_OPTS} "${SHARE_PATH}" "${TARGET_DIR}" > "${MOUNT_OUTPUT}" 2>&1 || touch "${SIGNAL}" ) &
	MOUNT_PID=$!
	for COUNTER in 1 1 2 4; do
	kill -0 "${MOUNT_PID}" 2>/dev/null || break
	sleep "${COUNTER}"
	done

	# check for failures
	if [ -e "${SIGNAL}" ]; then
	slxlog "pam-share-mount" "Mount of '${SHARE_PATH}' to '${TARGET_DIR}' failed. (Args: ${MOUNT_OPTS}" "${MOUNT_OUTPUT}"
	rm -f -- "${SIGNAL}"
	elif kill -9 "${MOUNT_PID}" 2>/dev/null; then
	slxlog "pam-share-mount" "Mount of '${SHARE_PATH}' to '${TARGET_DIR}' timed out. (Args: ${MOUNT_OPTS}" "${MOUNT_OUTPUT}"
	fi
	( sleep 2; rm -f -- "${MOUNT_OUTPUT}" ) &

	# always unset credentials
	unset USER
	unset PASSWD
}

############################################################################
#
#  MAIN LOGIC OVER ALL SHARES
#
############################################################################
# at this point we need the slx config to do anything
[ -e "/opt/openslx/config" ] || \
	{ slxlog "pam-share-noconfig" "File '/opt/openslx/config' not found."; return; }

# we have it as we should, source it
. /opt/openslx/config || \
	{ slxlog "pam-share-sourceconfig" "Could not source '/opt/openslx/config'."; return; }

#
#
#
# Since many shares can be specified, we need to identify how many we have first.
# We just go over all SLX_SHARE_* variables and check for those ending in _PATH.
# So e.g. for SLX_SHARE_0_PATH=<path> the SHARE variable would be equal to 'SLX_SHARE_0_PATH'
# For each of those, a share was specified and we will try to mount it.
for SHARE in $(grep -E '^SLX_SHARE_[0-9]+_PATH=.*$' /opt/openslx/config); do
	# first let's check if we have already mounted it and skip if it is
	# TODO: this should be good enough? stronger checks?
	if mount | grep -q "$(echo ${SHARE} | awk -F '=' '{print $2}' | tr -d \'\")"; then
		# already mounted, just skip
		# this should not happen anyway, since the pam_script_auth script also exits
		# if the temporary home user directory is already mounted...
		continue
	fi
	# ok so we have the full declaration command in $SHARE,
	# let's extract the number of the share.
	# i.e. SLX_SHARE_0_PATH -> share number 0
	# first just cut everything after '='
	SHARE_ID="$(echo $SHARE | awk -F '=' '{print $1}')"
	# now strip the leading SLX_SHARE_
	SHARE_ID=${SHARE_ID#SLX_SHARE_}
	# now remove the trailing _PATH
	SHARE_ID=${SHARE_ID%_PATH}
	# now it should be a number, TODO accept more than numbers? Doesn't really matter...
	# this check is mostly to be sure that the variable splitting worked as it should
	# ugly cause we need to be ash compatible ...
	if ! echo "${SHARE_ID}" | grep -q -E '^[0-9]+$'; then
		continue
	fi
	
	# now do try to mount the share using the helper function defined on the top of this script
	eval mount_share \""\$SLX_SHARE_${SHARE_ID}_AUTH_TYPE"\" \""\$SLX_SHARE_${SHARE_ID}_AUTH_USER"\" \""\$SLX_SHARE_${SHARE_ID}_AUTH_PASS"\" \""\$SLX_SHARE_${SHARE_ID}_PERM"\" \""\$SLX_SHARE_${SHARE_ID}_PATH"\" \""$SHARE_ID"\"
	## unset USER and PASSWD just in case mount_share returned due to an error.
	unset USER
	unset PASSWD
done