prasadtalasila/TransportScheduler

defmodule Station.Functions do
  @moduledoc """
  Module listing possible functions to use to compute congestion_delay value
  based on delay and some factor for multiplication. Based on the choice of
  function when Station local variables are being updated, a different
  mathematical formula gives the final congestion delay value from the original
  base delay value and the factor value.
  """

  @doc """
  Congestion computation function 1.
  Computes congestion_delay=delay*factor.
  ### Parameters
  delay
  factor
  ### Return values
  Returns congestion_delay value.
  """
  def compute_congestion_delay1(delay, factor) do
    _ = delay * factor
  end

  @doc """
  Congestion computation function 2.
  Computes congestion_delay=delay*factor+0.2.
  ### Parameters
  delay
  factor
  ### Return values
  Returns congestion_delay value.
  """
  def compute_congestion_delay2(delay, factor) do
    _ = delay * factor + 0.2
  end

  @doc """
  Congestion computation function 3.
  Computes congestion_delay=delay*factor*factor.
  ### Parameters
  delay
  factor
  ### Return values
  Returns congestion_delay value.
  """
  def compute_congestion_delay3(delay, factor) do
    _ = delay * factor * factor
  end

  @doc """
  Chooses congestion computation function.
  ### Parameters
  choose_fn
  ### Return values
  Returns congestion_delay value based on function chosen to compute it.
  """
  def func(choose_fn) do
    # appropriate function is called using choose_fn value as Map key
    Map.get(
      %{
        1 => fn delay, factor ->
          compute_congestion_delay1(delay, factor)
        end,
        2 => fn delay, factor ->
          compute_congestion_delay2(delay, factor)
        end,
        3 => fn delay, factor ->
          compute_congestion_delay3(delay, factor)
        end
      },
      choose_fn
    )
  end
end