defmodule LogLevel do
  @doc """
  Log code    Log label      Supported in legacy apps?
  0           trace          no
  1           debug          yes
  2           info           yes
  3           warning	       yes
  4           error          yes
  5           fatal          no
  other       unknown        -

  case {level, legacy?} do
    {0, false} -> :trace
    {1, _} -> :debug
    {2, _} -> :info
    {3, _} -> :warning
    {4, _} -> :error
    {5, false} -> :fatal
    _ -> :unknown
  end

  """
  def to_label(level, legacy?) do
    cond do
      level == 0 and not legacy? -> :trace
      level == 1 -> :debug
      level == 2 -> :info
      level == 3 -> :warning
      level == 4 -> :error
      level == 5 and not legacy? -> :fatal
      true -> :unknown
    end
  end

  @doc """
  If the log label is error or fatal, send the alert to the ops team. If you receive a log with an unknown label from a legacy system, send the alert to the dev1 team, other unknown labels should be sent to the dev2 team. All other log labels can be safely ignored by returning false.
  """
  def alert_recipient(level, legacy?) do
    label = to_label(level, legacy?)
    cond do
      label in [:error, :fatal] -> :ops
      label == :unknown and legacy? -> :dev1
      label == :unknown -> :dev2
      true -> false
    end
  end
end