defmodule Avatador.Helpers.List do
  require Integer

  @moduledoc """
    List Helpers
  """

  @doc """
    Turn a list of binary encoded hexadecimal into a 5x5 grid. Mirroring of
    each row is applied to create symmetry.
  """
  @doc since: "0.1.0"
  def integer_list_to_grid(list) do
    list
    |> Enum.chunk_every(3)
    |> Enum.flat_map(&mirror/1)
    |> Enum.with_index
  end

  @doc """
    Mirror a `List`.
    e.g. [1, 2, 3] -> [1, 2, 3, 2, 1]
  """
  @doc since: "0.1.0"
  def mirror(row) do
    len = Enum.count row
    reversed = Enum.reverse(row)

    case Integer.is_even(len) do
      true ->
        List.flatten [row | reversed]
      false ->
        List.flatten [row | tl(reversed)]
    end
  end
end