#REQUIRES THE FOLLOWING ENVIRONMENT VARIABLES: APPD_USER, APPD_PASS
require "rest-client"
require "json"
require "date"
require "active_support/all"

class AppD

  def get_time(datapoint)
      time = datapoint[:startTimeInMillis] || ""
      return time
  end

  def get_value(datapoint)
      value = datapoint[:value] || 0
      return value.round(2)
  end

  def query(metric_path, since=nil)
    @APPD_METRIC_URL = "<your AppDynamics url>"
    since ||= 3
    start_millis = (Time.now - (since*60*60)).to_f * 1000.0
    query_params = {
      "metric-path": metric_path,
      "time-range-type": "BETWEEN_TIMES",
      "start-time": start_millis.floor,
      "end-time": (Time.now.to_f * 1000.0).floor,
      "rollup": "false",
      "output": "json"
    }
    url = "#{@APPD_METRIC_URL}?#{query_params.to_param}"
    response = RestClient::Request.execute method: :get, url: url, user: "#{ENV["APPD_USER"]}@<your account>", password: ENV["APPD_PASS"]
    result = JSON.parse(response.body, :symbolize_names => true)
    return result.first
  end

  def total_since(name, since=nil)
    stats = query name, since
    total = stats[:metricValues].select{|el| not (el.nil? or el[:value].nil?)}.map{|e| get_value(e)}.sum
    return total
  end

  def points(name, since=nil)
    stats = query name, since
    points = []
    if stats.key?(:metricValues)
      datapoints = stats[:metricValues]

      (datapoints.select { |el| not el[0].nil? }).each do|item|
        points << { x: get_time(item), y: get_value(item)}
      end
    end
    return points
  end

  def value(name, since=nil)
    stats = query name, since
    last = (stats[:metricValues].select { |el| not (el.nil? or el[:value].nil?) }).last
    return get_value(last)
  end
end