defmodule Guardian.Permissions.TextEncoding do
  @moduledoc """
  Text encoding for permissions.
  """

  @behaviour Guardian.Permissions.PermissionEncoding
  import Bitwise

  def encode(value, type, perm_set) when is_integer(value) do
    perms = Map.get(perm_set, type)

    for {k, v} <- perms, band(value, v) == v, into: [] do
      to_string(k)
    end
  end

  def encode(value, type, perm_set) when is_list(value) do
    perms = Map.get(perm_set, type)
    Enum.reduce(value, [], &encode_value(&1, perms, &2))
  end

  defp encode_value(value, _perm_set, acc) when is_atom(value),
    do: [Atom.to_string(value) | acc]

  defp encode_value(value, _perm_set, acc) when is_binary(value),
    do: [value | acc]

  def decode(value, _type, _perm_set) when is_list(value) do
    Enum.map(value, &String.to_atom/1)
  end

  def decode(value, _type, _perm_set) do
    value
  end
end