defmodule Argos.Logger do
  @moduledoc """
  Handler de Logger para Argos con formateo basado en Aurora.

  Redirige eventos de `Logger` al módulo configurado (por defecto
  `Argos.Logger.Default`). Filtra niveles según configuración del proyecto.

  ## Configuración

  Cada proyecto puede configurar su propio logger y niveles permitidos:

      config :argos, :logger, MiProyecto.Logger.Custom
      config :argos, :logger_levels, [:debug, :info, :warning, :error]

  Los errores siempre se muestran, independientemente de la configuración.
  En modo develop, todos los niveles configurados se muestran.
  En modo producción, solo se muestran errores a menos que se configuren otros niveles.

  ## Modo Raw

  Los loggers pueden implementar `log_raw/3` para soportar modo raw,
  donde pueden calcular el tamaño del TUI y posicionar los logs debajo del TUI.
  """

  @behaviour :gen_event

  @impl true
  def init(__MODULE__) do
    logger_impl = Application.get_env(:argos, :logger, Argos.Logger.Default)

    unless function_exported?(logger_impl, :log, 3) do
      raise ArgumentError,
            "Logger implementation #{inspect(logger_impl)} must implement Argos.Logger.Behaviour"
    end

    env = current_env()
    app_name = get_app_name()
    configured_levels = get_configured_levels(app_name, env)

    {:ok,
     %{
       logger_impl: logger_impl,
       env: env,
       handler_id: Argos.Logger,
       app_name: app_name,
       configured_levels: configured_levels,
       raw_mode: Application.get_env(app_name, :logger_raw_mode, false)
     }}
  end

  @impl true
  def handle_event({_level, gl, _event}, state) when node(gl) != node() do
    {:ok, state}
  end

  @impl true
  def handle_event({level, _gl, {Logger, msg, ts, md}}, state) do
    if should_log?(state.env, level, state.configured_levels) do
      try do
        metadata = prepare_metadata(md, ts, level)
        message = extract_message(msg)

        if state.raw_mode && function_exported?(state.logger_impl, :log_raw, 3) do
          state.logger_impl.log_raw(level, message, metadata)
        else
          state.logger_impl.log(level, message, metadata)
        end
      rescue
        e ->
          IO.puts(:stderr, "Argos.Logger error: #{inspect(e)}")
      end
    end

    {:ok, state}
  end

  @impl true
  def handle_event(_event, state) do
    {:ok, state}
  end

  @impl true
  def handle_call(:get_config, state) do
    {:ok, state, state}
  end

  @impl true
  def handle_call({:configure, new_config}, state) do
    {:ok, :ok, Map.merge(state, new_config)}
  end

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

  @impl true
  def code_change(_old_vsn, state, _extra) do
    {:ok, state}
  end

  @impl true
  def terminate(_reason, _state) do
    :ok
  end

  defp should_log?(_env, level, _configured_levels)
       when level in [:error, :critical, :emergency, :alert],
       do: true

  defp should_log?(:prod, level, configured_levels) do
    level in configured_levels
  end

  defp should_log?(_env, level, configured_levels) do
    level in configured_levels
  end

  defp current_env do
    case System.get_env("ARGOS_ENV") || Application.get_env(:argos, :env, "dev") do
      "prod" -> :prod
      "dev" -> :dev
      "test" -> :test
      :prod -> :prod
      :dev -> :dev
      :test -> :test
      _ -> :dev
    end
  end

  defp get_app_name do
    case Application.get_env(:argos, :logger_app_name) do
      nil ->
        case Application.get_env(:argos, :logger) do
          nil ->
            :argos

          module when is_atom(module) ->
            module
            |> Module.split()
            |> List.first()
            |> String.downcase()
            |> String.to_atom()

          _ ->
            :argos
        end

      app_name ->
        app_name
    end
  end

  defp get_configured_levels(app_name, env) do
    case Application.get_env(app_name, :logger_levels) do
      nil ->
        case env do
          :prod -> [:error, :critical, :emergency, :alert]
          _ -> [:debug, :info, :warning, :error, :critical, :emergency, :alert]
        end

      levels when is_list(levels) ->
        error_levels = [:error, :critical, :emergency, :alert]
        (levels ++ error_levels) |> Enum.uniq()
    end
  end

  defp prepare_metadata(md, ts, level) do
    base_md = [
      timestamp: ts,
      level: level,
      handler_id: Argos.Logger
    ]

    useful_md =
      Enum.filter(md, fn
        {:module, _} -> true
        {:function, _} -> true
        {:file, _} -> true
        {:line, _} -> true
        {:application, _} -> true
        {:pid, _} -> true
        _ -> false
      end)

    base_md ++ useful_md
  end

  defp extract_message(msg) when is_binary(msg), do: msg
  defp extract_message({:string, chardata}), do: IO.chardata_to_string(chardata)

  defp extract_message({:fmt, format, args}),
    do: :io_lib.format(format, args) |> IO.chardata_to_string()

  defp extract_message(other), do: inspect(other)
end