quill

defmodule Quill do
  @moduledoc """
  Documentation for Quill.
  """

  alias Quill.{Builder, Encoder}

  @behaviour :gen_event

  def init(__MODULE__) do
    {:ok, configure(Application.get_env(:logger, Quill, []), default_state())}
  end

  def handle_call({:configure, options}, state) do
    {:ok, :ok, configure(options, state)}
  end

  def handle_info(_msg, state) do
    {:ok, state}
  end

  def terminate(_reason, _state) do
    :ok
  end

  def code_change(_old, state, _extra) do
    {:ok, state}
  end



  def handle_event(:flush, state) do
    {:ok, state}
  end

  def handle_event({_, gl, {Logger, _, _, _}}, state) when node(gl) != node() do
    {:ok, state}
  end

  def handle_event({level, _, {Logger, message, timestamp, metadata}}, state) do
    try do
      %{}
      |> Builder.add_base_fields(message, level, timestamp, state)
      |> Builder.add_metadata_fields(metadata, state)
      |> Encoder.encode()
      |> output_log(state)
    rescue
      e -> output_error(e, state)
    end
    {:ok, state}
  end



  defp configure(options, state) do
    state
    |> Map.merge(Enum.into(options, %{}))
  end

  defp default_state do
    %{
      level: :debug,
      io_device: :stdio,
      log_error: true,
      metadata: nil,
      version: 0,
    }
  end

  defp output_log(msg, config) do
    IO.puts(config.io_device, msg)
  end

  defp output_error(e, config) do
    case config.log_error do
      true -> IO.puts(config.io_device, inspect(e))
      _ -> :ok
    end
  end
end