#! /usr/bin/env ruby
#
# ec2-count-metrics
#
# DESCRIPTION:
#   This plugin retrieves number of EC2 instances
#
# OUTPUT:
#   plain-text
#
# PLATFORMS:
#   Linux
#
# DEPENDENCIES:
#   gem: aws-sdk-v1
#   gem: sensu-plugin
#
# USAGE:
#   #YELLOW
#
# NOTES:
#
# LICENSE:
#   Copyright (c) 2014, Tim Smith, tsmith@chef.io
#   Released under the same terms as Sensu (the MIT license); see LICENSE
#   for details.
#

require 'sensu-plugin/metric/cli'
require 'aws-sdk-v1'

class EC2Metrics < Sensu::Plugin::Metric::CLI::Graphite
  option :scheme,
         description: 'Metric naming scheme, text to prepend to metric',
         short: '-s SCHEME',
         long: '--scheme SCHEME',
         default: 'sensu.aws.ec2'

  option :aws_access_key,
         short: '-a AWS_ACCESS_KEY',
         long: '--aws-access-key AWS_ACCESS_KEY',
         description: "AWS Access Key. Either set ENV['AWS_ACCESS_KEY'] or provide it as an option",
         default: ENV['AWS_ACCESS_KEY']

  option :aws_secret_access_key,
         short: '-k AWS_SECRET_KEY',
         long: '--aws-secret-access-key AWS_SECRET_KEY',
         description: "AWS Secret Access Key. Either set ENV['AWS_SECRET_KEY'] or provide it as an option",
         default: ENV['AWS_SECRET_KEY']

  option :aws_region,
         short: '-r AWS_REGION',
         long: '--aws-region REGION',
         description: 'AWS Region (defaults to us-east-1).',
         default: 'us-east-1'

  option :type,
         short: '-t METRIC type',
         long: '--type METRIC type',
         description: 'Count by type: status, instance',
         default: 'instance'

  def aws_config
    { access_key_id: config[:aws_access_key],
      secret_access_key: config[:aws_secret_access_key],
      region: config[:aws_region] }
  end

  def by_instances_status(client)
    if config[:scheme] == 'sensu.aws.ec2'
      config[:scheme] += '.count'
    end

    options = { include_all_instances: true }
    data = client.describe_instance_status(options)

    total = data[:instance_status_set].count
    status = {}

    unless total.nil?
      data[:instance_status_set].each do |value|
        stat = value[:instance_state][:name]
        status[stat] = if status[stat].nil?
                         1
                       else
                         status[stat] + 1
                       end
      end
    end

    unless data.nil? # rubocop: disable Style/GuardClause
      # We only return data when we have some to return
      output config[:scheme] + '.total', total
      status.each do |name, count|
        output config[:scheme] + ".#{name}", count
      end
    end
  end

  def by_instances_type(client)
    if config[:scheme] == 'sensu.aws.ec2'
      config[:scheme] += '.types'
    end

    data = {}

    instances = client.describe_instances
    instances[:reservation_set].each do |i|
      i[:instances_set].each do |instance|
        type = instance[:instance_type]
        data[type] = if data[type].nil?
                       1
                     else
                       data[type] + 1
                     end
      end
    end

    unless data.nil? # rubocop: disable Style/GuardClause
      # We only return data when we have some to return
      data.each do |name, count|
        output config[:scheme] + ".#{name}", count
      end
    end
  end

  def run
    begin

      client = AWS::EC2::Client.new aws_config

      if config[:type] == 'instance'
        by_instances_type(client)
      elsif config[:type] == 'status'
        by_instances_status(client)
      end

    rescue => e
      puts "Error: exception: #{e}"
      critical
    end
    ok
  end
end