defmodule RBAC do
  @moduledoc """
  Documentation for `Rbac`.
  """

  @doc """
  Transform a list of maps (roles) to comma-separated string of ids.

  ## Examples

      iex> RBAC.transform_role_list_to_string([%{id: 1}, %{id: 2}, %{id: 3}])
      "1,2,3"

      iex> RBAC.transform_role_list_to_string("1,2,3")
      "1,2,3"

      iex> RBAC.transform_role_list_to_string(%{name: "sub", id: 1, revoked: nil})
      "1"

      iex> RBAC.transform_role_list_to_string([%{id: 1, revoked: 1}, %{id: 3}])
      "3"
  """
  def transform_role_list_to_string(roles) when is_list(roles) do
    # remove any roles that have been revoked:
    Enum.filter(roles, fn role ->
      not Map.has_key?(role, :revoked) or is_nil(role.revoked)
    end)
    |> Enum.map_join(",", &(&1.id))
  end

  # this guard is meant to return the string form if it's already defined:
  def transform_role_list_to_string(roles) when is_binary(roles) do
    roles
  end

  # if roles is a struct/map then attempt to parse it:
  def transform_role_list_to_string(roles) do
    [Map.delete(roles, :__meta__)] |> transform_role_list_to_string()
  end
end