require 'multi_json'

module StackDriver
  POST_URI = "https://custom-gateway.stackdriver.com/v1/custom"
  DELETE_URI = "https://custom-gateway.stackdriver.com/v1/delete_custom"

def self.init *args  
  if args.count > 1
    puts "Customer ID is no longer needed, and will be deprecated"
    args.shift
  end
  @api_key = args[0]
end

  def self.send_metric name, value, time, instance=''
    msg = build_message name, value, time, instance
    post MultiJson.dump(msg), StackDriver::POST_URI
  end

  def self.send_multi_metrics data
    msg = build_multi_message data
    post MultiJson.dump(msg), StackDriver::POST_URI
  end

  def self.delete_metric name, time
    msg = build_message name, nil, time
    post MultiJson.dump(msg), StackDriver::DELETE_URI
  end

  private

  def self.post msg, uri
    headers = {'content-type' => 'application/json',
      'x-stackdriver-apikey' => @api_key}

    uri = URI(uri)
    http = Net::HTTP.new(uri.host, uri.port)
    http.use_ssl = true

    http.start do |http|
      response = http.post(uri.path, msg, headers)
      if response.code != "201"
        raise RuntimeError, "#{response.code} - #{response.body}"
      end
    end
  end

  def self.build_message name, value, time, instance=''
    data_point = {'name' => name, 'value' => value, 'collected_at' => time}
    data_point.merge!('value' => value) unless value.nil?
    data_point.merge!('instance' => instance) unless instance.empty?
    {'timestamp' => Time.now.to_i, 'proto_version' => '1', 'data' => data_point}
  end

  def self.build_multi_message data
    data_point = data
    {
        'timestamp' => Time.now.to_i,
        'proto_version' => '1',
        'data' => data_point
    }
  end
end