exometer_zabbix

defmodule Exometer.Report do
  @moduledoc """
  Behaviour module for exometer_report in Elixir
  """

  @type state :: term
  @type callback_result :: {:ok, state} | :ignore

  @doc """
  Invoked when exometer reporter is started
  """
  @callback exometer_init(opts :: term) :: callback_result

  @doc """
  Invoked when a metric is being reported as part of a subscription
  """
  @callback exometer_report(
              :exometer_report.metric(),
              :exometer_report.datapoint(),
              :exometer_report.extra(),
              value :: term,
              state
            ) :: callback_result

  @doc """
  Invoked when reporter is being subscribed to a metric
  """
  @callback exometer_subscribe(
              :exometer_report.metric(),
              :exometer_report.datapoint(),
              :exometer_report.interval(),
              :exometer_report.extra(),
              state
            ) :: callback_result

  @doc """
  Invoked when reporter is being unsubscribed from a metric
  """
  @callback exometer_unsubscribe(
              :exometer_report.metric(),
              :exometer_report.datapoint(),
              :exometer_report.extra(),
              state
            ) :: callback_result

  @doc false
  @callback exometer_call(
              msg :: term,
              pid,
              state
            ) :: callback_result

  @doc false
  @callback exometer_cast(
              msg :: term,
              state
            ) :: callback_result

  @doc false
  @callback exometer_info(
              msg :: term,
              state
            ) :: callback_result

  @doc false
  @callback exometer_newentry(
              :exometer.entry(),
              state
            ) :: callback_result

  @doc false
  @callback exometer_setopts(
              :exometer_report.metric(),
              opts :: term
            ) :: callback_result
  @doc false
  @callback exometer_terminate(
              opts :: term,
              state
            ) :: callback_result

  @doc false
  defmacro __using__(_) do
    quote location: :keep do
      @behaviour :exometer_report

      @doc false
      def exometer_subscribe(_metric, _datapoint, _interval, _opts, state) do
        {:ok, state}
      end

      @doc false
      def exometer_unsubscribe(_metric, _datapoint, _extra, state) do
        {:ok, state}
      end

      @doc false
      def exometer_call(_msg, _from, state) do
        {:ok, state}
      end

      @doc false
      def exometer_cast(_msg, state) do
        {:ok, state}
      end

      @doc false
      def exometer_info(_msg, state) do
        {:ok, state}
      end

      @doc false
      def exometer_newentry(_entry, state) do
        {:ok, state}
      end

      @doc false
      def exometer_setopts(_metric, _options, _status, state) do
        {:ok, state}
      end

      @doc false
      def exometer_terminate(_reason, _state) do
        :ignore
      end

      defoverridable exometer_call: 3,
                     exometer_cast: 2,
                     exometer_info: 2,
                     exometer_newentry: 2,
                     exometer_setopts: 4,
                     exometer_terminate: 2,
                     exometer_subscribe: 5,
                     exometer_unsubscribe: 4
    end
  end
end