#! /usr/bin/env ruby
#
# check-cassandra-throughput
#
# DESCRIPTION:
#   This plugin uses Apache Cassandra's `nodetool` to check to see
#   if any node in the cluster has run into a schema disagreement problem
#
# OUTPUT:
#   plain text
#
# PLATFORMS:
#   Linux
#
# DEPENDENCIES:
#   gem: sensu-plugin
#   gem: english
#   Cassandra's nodetool
#
# USAGE:
#   command => check-cassandra-throughput --operation <read|write> --measurement <latency|throughtput>
#
# LICENSE:
#   Copyright 2014 Sonian, Inc. and contributors. <support@sensuapp.org>
#   Released under the same terms as Sensu (the MIT license); see LICENSE
#   for details.
#

require 'sensu-plugin/check/cli'
require 'English'

#
# Check Cassandra Throughput
#
class CheckCassandraThroughput < Sensu::Plugin::Check::CLI
  option :hostname,
         short: '-h HOSTNAME',
         long: '--host HOSTNAME',
         description: 'cassandra hostname',
         default: 'localhost'

  option :port,
         short: '-P PORT',
         long: '--port PORT',
         description: 'cassandra JMX port',
         default: '7199'

  option :operation,
         short: '-O OPERATION',
         long: '--operation OPERATION',
         description: 'read or write op',
         default: 'read'

  option :measurement,
         short: '-M MEASUREMENT',
         long: '--measurement MEASUREMENT',
         description: 'latency or throughput',
         default: 'latency'

  option :threshold,
         short:'-T THRESHHOLD',
         long: '--threshold THRESHOLD',
         description: 'Value at which the system will warm',
         default: '1000000'

  # execute cassandra's nodetool and return output as string
  def nodetool_cmd(cmd)
    out = `nodetool -h #{config[:hostname]} -p #{config[:port]} #{cmd} 2>&1`
    [out, $CHILD_STATUS]
  end

  def parse_cfstats
    def get_metric(string) # rubocop:disable NestedMethodDefinition
      string.strip!
      (metric, value) = string.split(': ')
      if metric.nil? || value.nil? # rubocop:disable Style/GuardClause
        return [nil, nil]
      else
        # sanitize metric names for graphite
        metric.gsub!(/[^a-zA-Z0-9]/, '_')  # convert all other chars to _
        metric.gsub!(/[_]*$/, '')          # remove any _'s at end of the string
        metric.gsub!(/[_]{2,}/, '_')       # convert sequence of multiple _'s to single _
        metric.downcase!
        # sanitize metric values for graphite. Numbers only, please.
        # some versions of nodetool omit the '.' following the 'ms' unit.
        value = value.chomp(' ms.').chomp(' ms')
      end
      [metric, value]
    end

    cfstats = nodetool_cmd('cfstats')

    metric = [config[:operation],config[:measurement]].join("_")

    cfstats[0].each_line do |line|
      result = get_metric(line)
      if result[0] == metric and result[1].to_f >= config[:threshold].to_f
        m = result.join(" ")
	warning(m)
      end
    end
  end

  def run
    parse_cfstats
    ok
  end
end