# -*- ruby -*-

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

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

# Disk capacity checks.

#

# Sets all configured mounts with their current usage percentage

# in an attribute named "mounts".

#

class Arborist::Monitor::SNMP::Disk

	include Arborist::Monitor::SNMP

	extend Configurability, Loggability

	log_to :arborist_snmp

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

	#

	STORAGE_NET_SNMP = {

		path:    '1.3.6.1.4.1.2021.9.1.2',

		percent: '1.3.6.1.4.1.2021.9.1.9',

		type:    '1.3.6.1.2.1.25.3.8.1.4',

		access:  '1.3.6.1.2.1.25.3.8.1.5'

	}

	# The OID that matches a local windows hard disk.

	#

	WINDOWS_DEVICES = [

		'1.3.6.1.2.1.25.2.1.4', # local disk

		'1.3.6.1.2.1.25.2.1.7'  # removables, but we have to include them for iscsi mounts

	]

	# OIDS required to pull disk information from Windows.

	#

	STORAGE_WINDOWS = {

		type:  '1.3.6.1.2.1.25.2.3.1.2',

		path:  '1.3.6.1.2.1.25.2.3.1.3',

		total: '1.3.6.1.2.1.25.2.3.1.5',

		used:  '1.3.6.1.2.1.25.2.3.1.6'

	}

	# The fallback warning capacity.

	WARN_AT = 90

	# Don't alert if a mount is readonly by default.

	ALERT_READONLY = false

	# Access mode meanings

	ACCESS_READWRITE = 1

	ACCESS_READONLY  = 2

	# Configurability API

	#

	configurability( 'arborist.snmp.disk' ) do

		# What percentage qualifies as a warning

		setting :warn_at, default: WARN_AT

		# Set down if the mounts are readonly?

		setting :alert_readonly, default: ALERT_READONLY

		# If non-empty, only these paths are included in checks.

		#

		setting :include do |val|

			if val

				mounts = Array( val ).map{|m| Regexp.new(m) }

				Regexp.union( mounts )

			end

		end

		# Paths to exclude from checks

		#

		setting :exclude,

			default: [ '^/dev(/.+)?$', '/dev$', '^/net(/.+)?$', '/proc$', '^/run$', '^/sys/', '/sys$' ] do |val|

			mounts = Array( val ).map{|m| Regexp.new(m) }

			Regexp.union( mounts )

		end

	end

	### Return the properties used by this monitor.

	###

	def self::node_properties

		used_properties = USED_PROPERTIES.dup

		used_properties << :mounts

		return used_properties

	end

	### Class #run creates a new instance and immediately runs it.

	###

	def self::run( nodes )

		return new.run( nodes )

	end

	### Perform the monitoring checks.

	###

	def run( nodes )

		super do |host, snmp|

			self.gather_disks( host, snmp )

		end

	end

	#########

	protected

	#########

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

	### +snmp+ connection.

	###

	def gather_disks( host, snmp )

		current_mounts = self.system =~ /windows\s+/i ? self.windows_disks( snmp ) : self.unix_disks( snmp )

		config         = self.identifiers[ host ].last['config'] || {}

		warn_at        = config[ 'warn_at' ] || self.class.warn_at

		alert_readonly = config[ 'alert_readonly' ] || self.class.alert_readonly

		self.log.debug self.identifiers[ host ]

		includes = self.format_mounts( config, 'include' ) || self.class.include

		excludes = self.format_mounts( config, 'exclude' ) || self.class.exclude

		current_mounts.reject! do |path, data|

			path = path.to_s

			excludes.match( path ) || ( includes && ! includes.match( path ) )

		end

		errors   = []

		warnings = []

		current_mounts.each_pair do |path, data|

			warn = if warn_at.is_a?( Hash )

				warn_at[ path ] || self.class.warn_at

			else

				warn_at

			end

			readonly = alert_readonly.is_a?( Hash ) ? alert_readonly[ path ] : alert_readonly

			self.log.debug "%s:%s -> %p, warn at %d" % [ host, path, data, warn ]

			if data[ :capacity ] >= warn.to_i

				if data[ :capacity ] >= 100

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

				else

					warnings << "%s at %d%% capacity" % [ path, data[ :capacity ] ]

				end

			end

			if readonly && data[ :accessmode ] == ACCESS_READONLY

				errors << "%s is mounted read-only." % [ path ]

			end

		end

		# Remove any past mounts that configuration exclusions should

		# now omit.

		mounts = self.identifiers[ host ].last[ 'mounts' ] || {}

		mounts.keys.each{|k| mounts[k] = nil }

		mounts.merge!( current_mounts )

		self.results[ host ] = { mounts: mounts }

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

		self.results[ host ][ :warning ] = warnings.join(', ') unless warnings.empty?

	end

	### Return a single regexp for the 'include' or 'exclude' section of

	### resource node's +config+, or nil if nonexistent.

	###

	def format_mounts( config, section )

		list = config[ section ] || return

		mounts = Array( list ).map{|m| Regexp.new(m) }

		return Regexp.union( mounts )

	end

	### Fetch information for Windows systems.

	###

	def windows_disks( snmp )

		paths = snmp.walk( oid: STORAGE_WINDOWS[:path] ).each_with_object( [] ) do |(_, value), acc|

			acc << value

		end

		types = snmp.walk( oid: STORAGE_WINDOWS[:type] ).each_with_object( [] ) do |(_, value), acc|

			acc << WINDOWS_DEVICES.include?( value )

		end

		totals = snmp.walk( oid: STORAGE_WINDOWS[:total] ).each_with_object( [] ) do |(_, value), acc|

			acc << value

		end

		used = snmp.walk( oid: STORAGE_WINDOWS[:used] ).each_with_object( [] ) do |(_, value), acc|

			acc << value

		end

		disks = {}

		paths.each_with_index do |path, idx|

			next if totals[ idx ].zero?

			next unless types[ idx ]

			disks[ path ] ||= {}

			disks[ path ][ :capacity ] = (( used[idx].to_f / totals[idx] ) * 100).round( 1 )

		end

		return disks

	end

	### Fetch information for Unix/MacOS systems.

	###

	def unix_disks( snmp )

		paths = snmp.walk( oid: STORAGE_NET_SNMP[:path] ).each_with_object( [] ) do |(_, value), acc|

			acc << value

		end

		capacities = snmp.walk( oid: STORAGE_NET_SNMP[:percent] ).each_with_object( [] ) do |(_, value), acc|

			acc << value

		end

		accessmodes = snmp.walk( oid: STORAGE_NET_SNMP[:access] ).each_with_object( [] ) do |(_, value), acc|

			acc << value

		end

		pairs = paths.each_with_object( {} ).with_index do |(p, acc), idx|

			acc[p] = { capacity: capacities[idx], accessmode: accessmodes[idx] }

		end

		return pairs

	end

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