require 'rubygems' if RUBY_VERSION < '1.9.0'
require 'em-http-request'
require 'eventmachine'
require 'multi_json'
require 'sensu/extension'

module Sensu
  module Extension
    class History < Bridge
      def name
        definition[:name]
      end

      def definition
        {
          type: 'extension',
          name: 'history'
        }
      end

      def description
        'Sends check result data to influxdb'
      end

      def post_init
        @influx_conf = parse_settings
        logger.info("InfluxDB history extension initialiazed using #{@influx_conf['protocol']}://#{@influx_conf['host']}:#{@influx_conf['port']} - Defaults : db=#{@influx_conf['database']} precision=#{@influx_conf['time_precision']}")

        @relay = InfluxRelay.new
        @relay.init(@influx_conf)

        logger.info("History write buffer initiliazed : buffer flushed every #{@influx_conf['buffer_max_size']} points OR every #{@influx_conf['buffer_max_age']} seconds) ")
      end

      def run(event_data)
        if event_data[:check][:type] != 'standard' && event_data[:check][:type] != 'check'
          yield '', 0
          return
        end

        host = event_data[:client][:name]
        metric = event_data[:check][:name]
        timestamp = event_data[:check][:executed]
        value = event_data[:check][:status]
        output = "#{@influx_conf['scheme']}.checks.#{metric},host=#{host} value=#{value} #{timestamp}"

        @relay.push(@influx_conf['database'], @influx_conf['time_precision'], output)
        yield output, 0
      end

      def stop
        logger.info('Flushing history buffer before exiting')
        @relay.flush_buffer
        true
      end

      private

      def parse_settings
        settings = @settings['influxdb']
        if @settings.include?('history')
          settings.merge!(@settings['history'])
        end
        # default values
        settings['tags'] ||= {}
        settings['use_ssl'] ||= false
        settings['time_precision'] ||= 's'
        settings['protocol'] = settings['use_ssl'] ? 'https' : 'http'
        settings['buffer_max_size'] ||= 500
        settings['buffer_max_age'] ||= 6 # seconds
        settings['port'] ||= 8086
        settings['scheme'] ||= 'sensu'
      rescue => e
        logger.error("Failed to parse History settings #{e}")
      end

      def logger
        Sensu::Logger.get
      end
    end
  end
end