#! /usr/bin/env ruby
#
#   metrics-http-json.rb
#
# DESCRIPTION:
#   Hits an HTTP endpoint which emits JSON and pushes data into Graphite.
#
# OUTPUT:
#   Graphite formatted data
#
# PLATFORMS:
#   Linux
#
# DEPENDENCIES:
#   gem: sensu-plugin
#   gem: rest-client
#
# USAGE:
#   ./metrics-http-json.rb -u 'https://user:password@127.0.0.1:443
#
#   ./metrics-http-json.rb -u 'http://127.0.0.1:8080/jolokia/read/com\
#   .mchange.v2.c3p0:name=datasource,type=PooledDataSource' -s hostname.c3p0\
#    -m 'Connections::numConnections,BusyConnections::numBusyConnections'\
#    -o 'value'
#
# NOTES:
#   The metric option is a comma separated list of the metric (how it will
#   appear in Graphite) and the JSON key which holds the value you want to
#   graph. The object option is optional and is the name of the JSON object
#   which holds the key/value pairs you want to graph.
#
# LICENSE:
#   phamby@gmail.com
#   Released under the same terms as Sensu (the MIT license); see LICENSE
#   for details.
#

require 'sensu-plugin/metric/cli'
require 'rest-client'
require 'socket'
require 'json'
require 'uri'
#
# HttpJsonGraphite - see description above
#
class HttpJsonGraphite < Sensu::Plugin::Metric::CLI::Graphite
  option :url,
         description: 'Full URL to the endpoint',
         short: '-u URL',
         long: '--url URL',
         default: 'http://localhost:8080'

  option :scheme,
         description: 'Metric naming scheme',
         short: '-s SCHEME',
         long: '--scheme SCHEME',
         default: Socket.gethostname.to_s

  option :metric,
         description: 'Optional Metric/JSON key pair ex:Connections::numConnections',
         short: '-m METRIC::JSONKEY',
         long: '--metric METRIC::JSONKEY',
         default: nil

  option :headers,
         description: 'Additional HTTP request headers to send. Example: Authorization:XYZ,User-Agent:ABC',
         short: '-H HEADER1:val,HEADER2:val',
         long: '--headers HEADER1:val,HEADER2:val'

  option :object,
         description: 'The JSON object containing the data',
         short: '-o OBJECT',
         long: '--object OBJECT'

  option :insecure,
         description: 'By default, every SSL connection made is verified to be secure. This option allows you to disable the verification',
         short: '-k',
         long: '--insecure',
         boolean: true,
         default: false

  option :debug,
         short: '-d',
         long: '--debug',
         default: false

  def deep_value(hash, scheme = '')
    hash.each do |key, value|
      if value.is_a?(Hash)
        deep_value(value, "#{scheme}.#{key}")
      else
        output "#{scheme}.#{key}", value
      end
    end
  end

  def run
    puts "args config: #{config}" if config[:debug]

    scheme = config[:scheme].to_s
    metric_pair_input = config[:metric].to_s
    if config[:object]
      object = config[:object].to_s
    end

    header_dict = {}
    if config[:headers]
      config[:headers].split(',').each do |header|
        h, v = header.split(':', 2)
        header_dict[h] = v.strip
      end
    end

    # TODO: figure out what to do here
    url = URI.encode(config[:url].to_s) # rubocop:disable Lint/UriEscapeUnescape
    begin
      r = RestClient::Request.execute(
        url: url,
        method: :get,
        verify_ssl: !config[:insecure],
        headers: header_dict
      )

      puts "Http response: #{r}" if config[:debug]

      if config[:metric].nil?
        deep_value(::JSON.parse(r), scheme)
      else
        metric_pair_array = metric_pair_input.split(/,/)
        metric_pair_array.each do |m|
          metric, attribute = m.to_s.split(/::/)
          puts "metric: #{metric}, attribute: #{attribute}" if config[:debug]
          unless object.nil?
            ::JSON.parse(r)[object].each do |k, v|
              if k == attribute
                output([scheme, metric].join('.'), v)
              end
            end
          end
          ::JSON.parse(r).each do |k, v|
            if k == attribute
              output([scheme, metric].join('.'), v)
            end
          end
        end
      end
    rescue Errno::ECONNREFUSED
      critical "#{config[:url]} is not responding"
    rescue RestClient::RequestTimeout
      critical "#{config[:url]} Connection timed out"
    end
    ok
  end
end