defmodule Util.LambdaLogger do
  @moduledoc """
  Documentation for Logger.
  """

  use Agent

  @doc """
  Start Logger.

  `log_level` must be in `[:debug, :info, :warn, :error]`
  """
  def start(log_level \\ :info) do
    Agent.start_link(fn -> log_level end, name: __MODULE__)
  end

  @doc """
  Log Debug.
  """
  def debug(message), do: if log?(:debug), do: log("[DEBUG] #{message |> log_message}")

  @doc """
  Log Information.
  """
  def info(message), do: if log?(:info), do: log("[INFO] #{message |> log_message}")

  @doc """
  Log Warning.
  """
  def warn(message), do: if log?(:warn), do: log("[WARN] #{message |> log_message}")

  @doc """
  Log Error.
  """
  def error(message), do: if log?(:error), do: log("[ERROR] #{message |> log_message}")

  defp log_message(message) when is_binary(message), do: message
  defp log_message(message), do: inspect(message)

  defp log(message), do: IO.puts(:stderr, message)

  defp log_level do
    Agent.get(__MODULE__, & &1)
  end

  defp log?(level) do
    level |> log?(log_level())
  end

  defp log?(:debug, log_level) do
    case log_level do
      :debug -> true
      _ -> false
    end
  end

  defp log?(:info, log_level) do
    case log_level do
      :debug -> true
      :info -> true
      _ -> false
    end
  end

  defp log?(:warn, log_level) do
    case log_level do
      :debug -> true
      :info -> true
      :warn -> true
      _ -> false
    end
  end

  defp log?(:error, log_level) do
    case log_level do
      :debug -> true
      :info -> true
      :warn -> true
      :error -> true
      _ -> false
    end
  end
end