#! /bin/sh

# MIT License
#
# Copyright (c) 2016-2021 Josef Friedrich <josef@friedrich.rocks>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# OS has to be defined at the very start because it is used in the date
# functions below
OS=$(uname)

########################################################################
# Date functions
########################################################################

# This date function must be placed on the top of this file because
# they are used in some global variables.

# to_year ###

##
# Get the four digit year integer from now.
#
# Return:
#   The current 4 digit year.
##
_now_to_year() {
	date +%Y
}

##
# Convert a date in the format YYYY-MM-DD to a four digit year integer.
#
# Parameters:
#   a date in the format YYYY-MM-DD
#
# Return:
#   four digit year integer
##
_date_to_year() {
	local OPTIONS
	if [ "$OS" = 'Linux' ]; then
		OPTIONS="--date $1"
	# FreeBSD, Darwin
	else
		OPTIONS="-j -f %Y-%m-%d $1"
	fi
	date $OPTIONS +%Y
}

# to_datetime ###

##
# Convert a UNIX timestamp to a datetime string.
#
# Parameters:
#   UNIX timestamp
#
# Return:
#   %Y-%m-%d.%H:%M:%S
##
_timestamp_to_datetime() {
	local OPTIONS
	if [ "$OS" = 'Linux' ]; then
		OPTIONS="--date @$1"
	# FreeBSD, Darwin
	else
		OPTIONS="-j -f %s $1"
	fi
	date $OPTIONS +%Y-%m-%d.%H:%M:%S
}

# to_timestamp ###

##
# Get the current UNIX timestamp.
#
# Return:
#   The current UNIX timestamp
##
_now_to_timestamp() {
	date +%s
}

##
# Convert a datetime in the ctime format to a Unix timestamp.
# ctime is a textual representation of a datetime derived from the
# c function ctime (https://en.cppreference.com/w/c/chrono/ctime).
# The ctime string has the following format:  Www Mmm dd hh:mm:ss yyyy,
# where Www is the weekday, Mmm the month in letters, dd the day of the
# month, hh:mm:ss the time, and yyyy the year.
#
# see https://www.freebsd.org/cgi/man.cgi?query=strftime&sektion=3
#  %c is replaced by national representation of time and date.
#
# Parameters:
#   $1: Www Mmm dd hh:mm:ss yyyy
#
# Return:
#   UNIX timestamp
##
_ctime_to_timestamp() {
	local OPTIONS
	if [ "$OS" = 'Linux' ]; then
		OPTIONS='--date'
	# FreeBSD, Darwin
	else
		OPTIONS='-j -f %c'
	fi
	date $OPTIONS "$1" +%s
}

########################################################################
# Global variables
########################################################################

PROJECT_PAGES='https://github.com/Josef-Friedrich/check_zpool_scrub
https://exchange.icinga.com/joseffriedrich/check_zpool_scrub
https://exchange.nagios.org/directory/Plugins/System-Metrics/File-System/check_zpool_scrub/details'

VERSION=2.0
FIRST_RELEASE=2016-09-08
SHORT_DESCRIPTION="Monitoring plugin to check how long ago the last \
ZFS scrub was performed."
USAGE="check_zpool_scrub v$VERSION
Copyright (c) $(_date_to_year $FIRST_RELEASE)-$(_now_to_year) \
Josef Friedrich <josef@friedrich.rocks>

$SHORT_DESCRIPTION


Usage: check_zpool_scrub <options>

Options:
 -c, --critical=OPT_CRITICAL
    Interval in seconds for critical state.
 -p,--pool=OPT_POOL
    Name of the pool. If this option is omitted all pools are checked.
 -h, --help
    Show this help.
 -s, --short-description
    Show a short description / summary.
 -v, --version
    Show the version number.
 -w, --warning=OPT_WARNING
    Interval in seconds for warning state. Must be lower than -c.

Performance data:

POOL is the name of the pool

 - POOL_last_ago
    Time interval in seconds for last scrub.
 - POOL_progress
    Percent 0 - 100
 - POOL_speed
    MB per second.
 - POOL_time
    Time to go in seconds.

Details about the implementation of this monitoring plugin:

This monitoring plugin grabs the last scrub date from the command
'zpool status POOL'.
"
# The state the plugin exits with
STATE=

# Exit codes
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3

# Message of one pool
MESSAGE=
# Performance data of one pool
PERFORMANCE_DATA=

# Options from the command line interface
OPT_POOL=
# 1 month 60*60*24*31
OPT_WARNING=2678400
# 2 month 60*60*24*31*2
OPT_CRITICAL=5356800

# To avoid that the command 'zpool status pool' is called more than once
CURRENT_POOL=
ZPOOL_STATUS_STDOUT=
ZPOOL_STATUS_EXIT_CODE=

_getopts() {
	local OPT
	while getopts ':c:hp:svw:-:' OPT ; do
		case $OPT in
			c) OPT_CRITICAL=$OPTARG ;;
			h) echo "$USAGE" ; exit 0 ;;
			p) OPT_POOL="$OPTARG" ;;
			s) echo "$SHORT_DESCRIPTION" ; exit 0 ;;
			v) echo "$VERSION" ; exit 0 ;;
			w) OPT_WARNING=$OPTARG ;;

			\?)
				echo "Invalid option “-$OPTARG”!" >&2
				exit 2
				;;

			:)
				echo "Option “-$OPTARG” requires an argument!" >&2
				exit 3
				;;

			-)
				LONG_OPTARG="${OPTARG#*=}"

				case $OPTARG in

					critical=?*)
						OPT_CRITICAL=$LONG_OPTARG
						;;

					help)
						echo "$USAGE"
						exit 0
						;;

					pool=?*)
						OPT_POOL="$LONG_OPTARG"
						;;

					short-description)
						echo "$SHORT_DESCRIPTION"
						exit 0
						;;

					version)  echo "$VERSION" ; exit 0 ;;

					warning=?*)
						OPT_WARNING=$LONG_OPTARG
						;;

					help*|short-description*|version*)
						echo "No argument allowed for the option “--$OPTARG”!" >&2
						exit 4
						;;

					critical*|pool*|warning*)
						echo "Option “--$OPTARG” requires an argument!" >&2
						exit 3
						;;

					'')	# "--" terminates argument processing
						break
						;;

					*)
						echo "Invalid option “--$OPTARG”!" >&2
						exit 2
						;;

				esac
				;;

		esac
	done
}

##
# Detect the date of the last scrub.
#
# Grab the date string of the last scrub from the command 'zpool
# status'. Grabing the date from 'zpool history' is very slow on old
# pools with a lot of history.
#
# /* If there's never been a scan, there's not much to say. */ "none
#   requested\n" -> scan: none requested
#
# /* Scan is finished or canceled. */ "scrub repaired %s in %lluh%um
#   with %llu errors on %s" -> scan: scrub repaired 0 in 0h0m with 0
#   errors on Mon Aug  6 16:30:52 2018
#
#   "resilvered %s in %lluh%um with %llu errors on %s"
#
#   "scrub canceled on %s"
#
#   "resilver canceled on %s"
#
# /* Scan is in progress. */
#
#   "scrub in progress since %s"
#
#   "resilver in progress since %s"
#
# Parameters:
#  $1: The name of the pool.
#
# Return:
#  A UNIX timestamp
##
_grab_last_scrub_timestamp() {
	local CTIME
	CTIME="$(_get_zpool_status_stdout "$1" | grep '  scan: ' | sed -n -E "s/^.*(canceled on|in progress since|errors on) (.*)$/\2/p")"
	if [ -n "$CTIME" ]; then
		_ctime_to_timestamp "$CTIME"
	fi
}

##
# Assemble the performance data of one pool.
#
# Parameters:
#   $1: POOL
#   $2: LAST_AGO
#   $3: PROGRESS
#   $4: SPEED
#   $5: TIME
##
_performance_data_one_pool() {
	local POOL="$1_"
	echo "\
${POOL}last_ago=$2s;$OPT_WARNING;$OPT_CRITICAL;0 \
${POOL}progress=$3%;;;0;100 \
${POOL}speed=$4 \
${POOL}time=$5s"
}

##
# Grab the scrub progress from the 'zpool status' output.
#
# Parameters:
#   $1: The name of the pool.
#
# Return:
#   A floating point number from 0 to 100 that represents the progress
#  (for example '85.3').
##
_grab_progress() {
	local STDOUT
	STDOUT="$(_get_zpool_status_stdout "$1" | grep ' done' | sed -n -E "s/^.*, ([[:digit:]]{1,3}[,\.][[:digit:]]{1,2}%) done.*$/\1/p")"
	if [ -n "$STDOUT" ]; then
		echo "$STDOUT" | sed 's/%//' | tr ',' '.'
	else
		echo 100
	fi
}

##
# Grab the scrub speed from the 'zpool status' output.
#
# Parameters:
#   $1: The name of the pool.
#
# Return:
#   A floating point number like '57.4' or '1.9' in M/s.
##
_grab_speed() {
	local SPEED UNIT
	SPEED="$(_get_zpool_status_stdout "$1" | grep -E -o '[[:digit:]\.,]*[[:alpha:]]*/s')"
	SPEED="$(echo $SPEED | awk '{print $1}')"

	if [ -n "$SPEED" ]; then
		SPEED=$(echo "$SPEED" | sed 's#/s##' | tr , .)
		UNIT=$(echo -n "$SPEED" | tail -c 1)
		SPEED=$(echo "$SPEED" | sed 's/.$//' )

		if [ "$UNIT" = K ]; then
			SPEED="$(echo "$SPEED" | \
				awk '{MB = $1 / 1024 ; print MB}')"
		fi
		echo $SPEED
	else
		echo 0
	fi
}

##
# Extract the time to go from the 'zpool status' output.
#
# Responsible for the output see the ZFS source code:
# - https://github.com/openzfs/openzfs/blob/ed81aacb0d0fcbf7e0c0745ea4556655050c26bf/usr/src/cmd/zpool/zpool_main.c#L4441
# - https://github.com/openzfs/zfs/blob/a1ca39655ba446c98a2f44b2b1d45d1059738885/cmd/zpool/zpool_main.c#L7537
#
# For example:
# Input:
#   ...
#   scan: scrub in progress since Sun Aug 13 00:24:02 2017
#     7,34T scanned out of 10,1T at 57,4M/s, 14h12m to go
#     0 repaired, 72,38% done
#   ...
#
# Other solutions:
#
# Not working on FreeBSD:
#   grep -P -o '(?<=, )[[:digit:]]*h[[:digit:]]*m(?= to go)'
#
# Parameters:
#   $1: The name of the pool.
#
# Return:
#   The time to go in seconds as an integer number.
##
_grab_time_to_go() {
	local SECONDS MINUTES HOURS DAYS
	SECONDS=0
	MINUTES=0
	HOURS=0
	DAYS=0

	_get_line() {
		_get_zpool_status_stdout "$1" | grep ' to go'
	}

	 # some sh implementations (can) interpret numbers with leading zeros as octal numbers.
	_remove_leading_zeros() {
		local NUMBER
		NUMBER="$(echo "$1" | sed -E 's/^0*//')"
		if [ -n "$NUMBER" ]; then
			echo "$NUMBER"
		else
			echo 0
		fi
	}

	if [ -n "$(_get_line "$1" | grep '..:..:.. to go')" ]; then
		if [ -n "$(_get_line "$1" | grep days)" ]; then
			DAYS="$(_get_line "$1" | sed -E 's/^.* (.*) days .*$/\1/')"
		fi
		HOURS="$(_get_line "$1" | sed -E 's/^.* (..):.*$/\1/')"
		MINUTES="$(_get_line "$1" | sed -E 's/^.* ..:(..):.*$/\1/')"
		SECONDS="$(_get_line "$1" | sed -E 's/^.* ..:..:(..).*$/\1/')"
	elif [ -n "$(_get_line "$1" | grep 'h.*m.*to go')" ]; then
		_get_duration() {
			_get_line "$1" | sed -E 's/^.*, (.*h.*m) to go.*$/\1/'
		}
		HOURS=$(_get_duration "$1" | sed 's/h.*//')
		MINUTES=$(_get_duration "$1" | sed -E 's/^.*, (.*h.*m) to go.*$/\1/' | sed 's/.*h//' | sed 's/m//')
	fi

	DAYS="$(_remove_leading_zeros "$DAYS")"
	HOURS="$(_remove_leading_zeros "$HOURS")"
	MINUTES="$(_remove_leading_zeros "$MINUTES")"
	SECONDS="$(_remove_leading_zeros "$SECONDS")"

	echo $(((DAYS * 1440 + HOURS * 60 + MINUTES) * 60 + SECONDS))
}

##
# Get the stdout of the command 'zpool status'
# To avoid that the command 'zpool status' is executed more than once.
#
# Parameters:
#   $1: The name of the pool.
##
_get_zpool_status_stdout() {
	if [ -n "$ZPOOL_STATUS_STDOUT" ] && [ "$CURRENT_POOL" = "$1" ]; then
		echo "$ZPOOL_STATUS_STDOUT"
	else
		CURRENT_POOL=$1
		ZPOOL_STATUS_STDOUT="$(zpool status "$1")" > /dev/null 2>&1
		ZPOOL_STATUS_EXIT_CODE=$?
		echo "$ZPOOL_STATUS_STDOUT"
	fi
}

##
# Check one ZFS pool.
#
# Parameters:
#   $1: The name of the pool.
##
_check_one_pool() {
	local POOL NOW LAST_SCRUB DIFF PROGRESS SPEED TIME
	 POOL="$1"

	CURRENT_POOL=
	ZPOOL_STATUS_STDOUT=
	ZPOOL_STATUS_EXIT_CODE=
	_get_zpool_status_stdout "$1" > /dev/null 2>&1

	if [ "$ZPOOL_STATUS_EXIT_CODE" != 0 ]; then
		PERFORMANCE_DATA=
		MESSAGE="UNKNOWN: '${POOL}' is no ZFS pool."
		STATE=$STATE_UNKNOWN
		return
	fi

	NOW=$(_now_to_timestamp)
	LAST_SCRUB=$(_grab_last_scrub_timestamp "$POOL")

	if [ -z "$LAST_SCRUB" ]; then
		PERFORMANCE_DATA=
		MESSAGE="UNKNOWN: The pool '${POOL}' has never had a scrub."
		STATE=$STATE_UNKNOWN
		return
	fi

	DIFF=$((NOW - LAST_SCRUB))

	PROGRESS="$(_grab_progress "$POOL")"
	SPEED="$(_grab_speed "$POOL")"
	TIME="$(_grab_time_to_go "$POOL")"

	STATE=STATE_UNKNOWN

	if [ "$DIFF" -gt "$OPT_CRITICAL" ]; then
		STATE=$STATE_CRITICAL
		MESSAGE="CRITICAL:"
	elif [ "$DIFF" -gt "$OPT_WARNING" ]; then
		STATE=$STATE_WARNING
		MESSAGE="WARNING:"
	else
		STATE=$STATE_OK
		MESSAGE="OK:"
	fi

	PERFORMANCE_DATA="$(_performance_data_one_pool \
		"${POOL}" "${DIFF}" "${PROGRESS}" "${SPEED}" "${TIME}")"
	MESSAGE="$MESSAGE The last scrub on zpool '${POOL}' was \
performed on $(_timestamp_to_datetime $LAST_SCRUB)."

}

_check_multiple_pools() {
	local POOL GLOBAL_STATE=0 MESSAGES PERFORMANCE_DATAS

	for POOL in $@; do
		_check_one_pool "$POOL"

		if [ -n "${PERFORMANCE_DATAS}" ]; then
			PERFORMANCE_DATAS="${PERFORMANCE_DATAS} \
${PERFORMANCE_DATA}"
		else
			PERFORMANCE_DATAS="${PERFORMANCE_DATA}"
		fi

		if [ -n "${MESSAGES}" ]; then
			MESSAGES="${MESSAGES} ${MESSAGE}"
		else
			MESSAGES="${MESSAGE}"
		fi

		# If one pool is critical the global state turns to
		# critical.
		if [ "${STATE}" -eq 2 ]; then
			GLOBAL_STATE=2
		# warning
		elif [ "${STATE}" -eq 1 ] && \
				 ! [ ${GLOBAL_STATE} -eq 2 ]; then
			GLOBAL_STATE=1
		# unkown
		elif [ "${STATE}" -eq 3 ] && \
				 ! [ ${GLOBAL_STATE} -eq 1 ] && \
				 ! [ ${GLOBAL_STATE} -eq 2 ]; then
			GLOBAL_STATE=3
		fi
	done

	PERFORMANCE_DATA="${PERFORMANCE_DATAS}"
	MESSAGE="${MESSAGES}"
	STATE="$GLOBAL_STATE"
}

##
# Main function to jump in on execution.
#
# Parameters:
#   $@: All positional arguments provided by the script.
##
_main() {
	local POOL
	_getopts $@

	if [ "$OPT_WARNING" -gt "$OPT_CRITICAL" ]; then
		echo '<warntime> must be smaller than <crittime>.' >&2
		echo "$USAGE" >&2
		exit $STATE_UNKNOWN
	fi

	if [ -n "$OPT_POOL" ]; then
		_check_one_pool "$OPT_POOL"
	else
		_check_multiple_pools $(zpool list -H -o name)
	fi

	if [ -n "$PERFORMANCE_DATA" ]; then
		MESSAGE="$MESSAGE | \
${PERFORMANCE_DATA}"
	fi

	echo "$MESSAGE"
	exit $STATE
}

## This SEPARATOR is required for test purposes. Please don’t remove! ##

_main $@