# -*- ruby -*-

# vim: set noet nosta sw=4 ts=4 :

require 'arborist/monitor/snmp' unless defined?( Arborist::Monitor::SNMP )

# SNMP Disk capacity checks.

# Returns all mounts with their current usage percentage in a "mount" attribute.

#

class Arborist::Monitor::SNMP::Disk

	include Arborist::Monitor::SNMP

	extend Loggability

	log_to :arborist

	# The OID that returns the system environment.

	IDENTIFICATION_OID = '1.3.6.1.2.1.1.1.0'

	# For net-snmp systems, ignore mount types that match

	# this regular expression.  This includes null/union mounts

	# and NFS, currently.

	STORAGE_IGNORE = %r{25.3.9.(?:2|14)$}

	# The OID that matches a local windows hard disk.  Anything else

	# is a remote (SMB) mount.

	WINDOWS_DEVICE = '1.3.6.1.2.1.25.2.1.4'

	# OIDS required to pull disk information from net-snmp.

	#

	STORAGE_NET_SNMP = [

		'1.3.6.1.4.1.2021.9.1.2', # paths

		'1.3.6.1.2.1.25.3.8.1.4', # types

		'1.3.6.1.4.1.2021.9.1.9'  # percents

	]

	# OIDS required to pull disk information from Windows.

	#

	STORAGE_WINDOWS = [

		'1.3.6.1.2.1.25.2.3.1.2', # types

		'1.3.6.1.2.1.25.2.3.1.3', # paths

		'1.3.6.1.2.1.25.2.3.1.5', # totalsize

		'1.3.6.1.2.1.25.2.3.1.6'  # usedsize

	]

	# Global defaults for instances of this monitor

	#

	DEFAULT_OPTIONS = {

		error_at: 95, # in percent full

		include:  [], # if non-empty, only these paths are included in checks

		exclude:  []  # paths to exclude from checks

	}

	### This monitor is complex enough to require creating an instance from the caller.

	### Provide a friendlier error message the class was provided to exec() directly.

	###

	def self::run( nodes )

		return new.run( nodes )

	end

	### Create a new instance of this monitor.

	###

	def initialize( options=DEFAULT_OPTIONS )

		options = DEFAULT_OPTIONS.merge( options || {} )

		%i[ include exclude ].each do |opt|

			options[ opt ] = Array( options[opt] )

		end

		options.each do |name, value|

			self.public_send( "#{name.to_s}=", value )

		end

	end

	# Set an error if mount points are above this percentage.

	attr_accessor :error_at

	# Only check these specific mount points.

	attr_accessor :include

	# Exclude these mount points (array of paths) from checks.

	attr_accessor :exclude

	### Perform the monitoring checks.

	###

	def run( nodes )

		super do |snmp, host|

			self.gather_disks( snmp, host )

		end

	end

	#########

	protected

	#########

	### Collect mount point usage for +host+ from an existing (and open)

	#### +snmp+ connection.

	###

	def gather_disks( snmp, host )

		self.log.debug "Getting disk information for %s" % [ host ]

		errors  = []

		results = {}

		mounts  = self.get_disk_percentages( snmp )

		config  = @identifiers[ host ].last || {}

		includes = config[ 'include' ] || self.include

		excludes = config[ 'exclude' ] || self.exclude

		mounts.each_pair do |path, percentage|

			next if excludes.include?( path )

			next if ! includes.empty? && ! includes.include?( path )

			if percentage >= ( config[ 'error_at' ] || self.error_at )

				errors << "%s at %d%% capacity" % [ path, percentage ]

			end

		end

		results[ :mounts ] = mounts

		results[ :error ] = errors.join( ', ' ) unless errors.empty?

		@results[ host ] = results

	end

	### Given a SNMP object, return a hash of:

	###

	###    device path => percentage full

	###

	def get_disk_percentages( snmp )

		# Does this look like a windows system, or a net-snmp based one?

		system_type = snmp.get( SNMP::ObjectId.new( IDENTIFICATION_OID ) ).varbind_list.first.value

		disks = {}

		# Windows has it's own MIBs.

		#

		if system_type =~ /windows/i

			snmp.walk( STORAGE_WINDOWS ) do |list|

				next unless list[0].value.to_s == WINDOWS_DEVICE

				disks[ list[1].value.to_s ] = ( list[3].value.to_f / list[2].value.to_f ) * 100

			end

			return disks

		end

		# Everything else.

		#

		snmp.walk( STORAGE_NET_SNMP ) do |list|

			mount = list[0].value.to_s

			next if mount == 'noSuchInstance'

			next if list[2].value.to_s == 'noSuchInstance'

			used = list[2].value.to_i

			unless list[1].value.to_s == 'noSuchInstance'

				typeoid = list[1].value.join('.').to_s

				next if typeoid =~ STORAGE_IGNORE

			end

			next if mount =~ /\/(?:dev|proc)$/

			disks[ mount ] = used

		end

		return disks

	end

end # class Arborist::Monitor::SNMP::Disk