#!/bin/bash

if [ $# -lt 2 ]; then
	echo "Bad call to $0." >&2
	echo "Expected: $0 images <source>" >&2
	echo "TM_USERNAME and TM_PASSWORD are expected environment variables for CIFS" >&2
	echo "TM_MOUNT_OPTIONS can be supplied in both cases to override automatic guessing" >&2
	exit 1
fi

USERNAME="$TM_USERNAME"
PASSWORD="$TM_PASSWORD"
MOUNT_OPTIONS="$TM_MOUNT_OPTIONS"
unset TM_PASSWORD

declare -rg CIFS_OPTS="/opt/openslx/cifs.opts"
declare -rg NFS_OPTS="/opt/openslx/nfs.opts"

WHAT="$1"
SOURCE="$2"
[ -n "$3" ] && USERNAME="$3"
[ -n "$4" ] && PASSWORD="$4"

# Currently WHAT can only be images (the central store for all images),
# but maybe there will be other storage types in the future.
case "$WHAT" in
images)
	DEST="/srv/openslx/nfs"
	;;
*)
	echo "Invalid/Unknown mount type: '$WHAT'." >&2
	exit 1
	;;
esac

FLAG="${DEST}/.notmounted"
SUBDIR="${DEST}/bwlehrpool_store"

storage_test () {
	rm -f -- "${FLAG}"
	if [ -e "${FLAG}" ]; then
		echo "Error: File '.notmounted' exists on remote storage and could not be deleted." >&2
		echo "Error: Make sure the share is writable." >&2
		return 5
	fi
	chgrp images "${DEST}" 2>/dev/null
	mkdir -p "${SUBDIR}"
	if [ ! -d "${SUBDIR}" ]; then
		echo "Error: Could not create directory $(basename "${SUBDIR}")! Storage not writable!" >&2
		return 6
	fi
	echo "Applying group..."
	find "${SUBDIR}" -type d -exec chgrp images {} \; 2>/dev/null
	echo "Applying permissions..."
	find "${SUBDIR}" -type d -exec chmod ug+rwx {} \; 2>/dev/null
	echo "Creating test file..."
	local TEST="${SUBDIR}/.deleteme-$RANDOM-$RANDOM"
	sudo -n -u dmsd touch "$TEST"
	local RET=$?
	if [ -e "$TEST" ]; then
		sudo -n -u dmsd rm -f -- "$TEST"
	else
		[ "$RET" = "0" ] && RET=127
		echo "Error: Mounted share is not writable." >&2
		ls -al "${DEST}" "${SUBDIR}" >&2
	fi
	return $RET
}

systemctl stop dnbd3-server.service

# Already mounted?
TRIES=0
while awk '{print $2}' "/proc/mounts" | grep -Fxq "${DEST}"; do
	echo "Trying to unmount '$DEST'..."
	if [ "$TRIES" -gt 5 ]; then
		cat >&2 <<-HEREDOC
			Error: Cannot unmount '$DEST'!
			Storage might be in use (running VM upload etc.)
			Try stopping DMSD first

			If the problem persists, try rebooting the server.

			Possible troublemaker(s):
		HEREDOC
		lsof -n | grep "$DEST" >&2
		exit 99 # marker that nothing changed
	elif [ "$TRIES" -gt 3 ]; then
		umount -v -f "$DEST"
		RET=$?
	else
		umount -v "$DEST"
		RET=$?
	fi
	[ "$RET" = 0 ] && break
	sleep 1
	TRIES=$(( TRIES + 1 ))
done

# Sanity checks: Destination exists?
if [ ! -d "$DEST" ]; then
	mkdir -p "$DEST"
	chown root:images "$DEST"
	chmod 0775 "$DEST"
fi

# Still a no?
if [ ! -d "$DEST" ]; then
	echo "Mount point '$DEST' does not exist and could not be created!" >&2
	echo "This should not happen and means this server is severely messed up. :(" >&2
	exit 1
fi

# Unmount and not requested to mount (local mode)
if [[ "${SOURCE}" == "null" ]]; then
	rm -f -- "${FLAG}"
	echo "Success. Now using internal storage."
	systemctl --no-block start dnbd3-server.service
	exit 0
fi

touch "${FLAG}"

if [[ "${SOURCE}" == "unknown" ]]; then
	echo "Storage type not configured, doing nothing."
	exit 0
fi

# Mount!

# exec_mount <type> <options> <source> <dest>
exec_mount () {
	local fstype="$1"
	local mntopts="$2"
	local SOURCE="$3"
	local DEST="$4"
	echo " * Trying ${fstype} with ${mntopts}..."
	mount -v -t "$fstype" -o "$mntopts" "$SOURCE" "$DEST"
	RET=$?
	[ "$RET" -ne "0" ] && return "$RET"
	echo "Mount succeeded, checking write permissions...."
	storage_test
	RET=$?
	[ "$RET" -eq "0" ] && return 0
	umount -v "$DEST" || umount -v -f -l "$DEST"
	return "$RET"
}

remove_option () {
	local opt
	while [ $# -gt 0 ]; do
		opt=$1
		shift
		[[ "$MOUNT_OPTIONS" =~ (^|,)$opt($|,|=) ]] || continue
		MOUNT_OPTIONS=$( echo "$MOUNT_OPTIONS" | sed -r "s/(^|,)$opt(|=[^,]*)(,|$)/\\1/g;s/,$//" )
	done
}

main () {
	local RET=999
	if grep -E -q '^[^/].+:.+' <<<$SOURCE; then
		# seems to be NFS
		if [ "$RET" != 0 ] && [ -n "$MOUNT_OPTIONS" ]; then
			remove_option bg retry ro
			MOUNT_OPTIONS="$MOUNT_OPTIONS,fg,retry=0,rw"
			exec_mount "nfs" "$MOUNT_OPTIONS" "$SOURCE" "$DEST"
			return $?
		fi
		OPTSTR=
		if [ -f "$NFS_OPTS" ]; then
			OPTSTR=$(cat "$NFS_OPTS")
		fi
		if [ "$RET" != 0 ] && [ -n "$OPTSTR" ]; then
			echo " * Trying last successful mount options..."
			exec_mount "nfs" "$OPTSTR" "$SOURCE" "$DEST"
			RET=$?
		fi
		if [ "$RET" != 0 ]; then
			for opt in "#" "vers=4" "vers=3"; do
				OPTSTR="rw,noatime,noexec,nodev,async,nolock,fg,ac,retry=0,timeo=200,sec=sys"
				[ "$opt" != "#" ] && OPTSTR="$OPTSTR,$opt"
				exec_mount "nfs" "$OPTSTR" "$SOURCE" "$DEST"
				RET=$?
				[ "$RET" = 0 ] && break
			done
			if [ "$RET" = 0 ] && [ -n "$OPTSTR" ]; then
				echo "$OPTSTR" > "$NFS_OPTS"
			fi
		fi
	elif grep -E -q '^//' <<<$SOURCE; then
		# seems to be SMB
		export USER="$USERNAME"
		export PASSWD="$PASSWORD"
		if [ "$RET" != 0 ] && [ -n "$MOUNT_OPTIONS" ]; then
			remove_option uid gid file_mode dir_mode umask ro
			MOUNT_OPTIONS="$MOUNT_OPTIONS,uid=0,gid=12345,forceuid,forcegid,file_mode=0664,dir_mode=0775,rw"
			exec_mount "cifs" "$MOUNT_OPTIONS" "$SOURCE" "$DEST"
			return $?
		fi
		OPTSTR=
		if [ -f "$CIFS_OPTS" ]; then
			OPTSTR=$(cat "$CIFS_OPTS")
		fi
		if [ "$RET" != 0 ] && [ -n "$OPTSTR" ]; then
			echo " * Trying last successful mount options..."
			exec_mount "cifs" "$OPTSTR" "$SOURCE" "$DEST"
			RET=$?
		fi
		if [ "$RET" != 0 ]; then
			for vers in "" "3.0" "2.1" "2.0" "1.0"; do
				[ -n "$vers" ] && vers=",vers=${vers}"
				for sec in "" "ntlmssp" "ntlmv2" "ntlm"; do
					[ -n "$sec" ] && sec=",sec=${sec}"
					OPTSTR="rw,uid=0,gid=12345,forceuid,forcegid,nounix,file_mode=0664,dir_mode=0775$vers$sec"
					exec_mount "cifs" "$OPTSTR" "$SOURCE" "$DEST"
					RET=$?
					[ "$RET" = 0 ] && break 2
				done
			done
			if [ "$RET" = 0 ] && [ -n "$OPTSTR" ]; then
				echo "$OPTSTR" > "$CIFS_OPTS"
			fi
		fi
		unset USER PASSWD
	else
		echo "Unknown mount type: $SOURCE"
		RET=1
	fi
	return "$RET"
}

main
RET=$?

echo ""

if [ "$RET" = "0" ]; then
	echo "----------------------------------"
	echo "-- Share mounted successfully!  --"
	echo "----------------------------------"
	systemctl --no-block start dnbd3-server.service
fi

exit "$RET"