defmodule EctoEnumerize do
  @moduledoc """
  Provides `EctoEnumerize.defenum/2` macro for defining an Enum Ecto type.
  """

  @doc """
  Defines a custom Enum `Ecto.Type`.
  """

  @spec defenum(module(), key: integer()) :: Macro.t()
  defmacro defenum(module, enum) do
    quote do
      kw = unquote(enum) |> Macro.escape()

      defmodule unquote(module) do
        @behaviour Ecto.Type

        @atom_enum kw
        @string_enum for {atom, int} <- @atom_enum, into: %{}, do: {to_string(atom), atom}
        @int_enum for {atom, int} <- @atom_enum, into: %{}, do: {int, atom}

        def type(), do: :integer

        def cast(k) when is_atom(k) do
          if @atom_enum[k], do: {:ok, k}, else: :error
        end

        def cast(k) when is_binary(k) do
          if @string_enum[k], do: {:ok, @string_enum[k]}, else: :error
        end

        def cast(k) when is_integer(k) do
          if @int_enum[k], do: {:ok, @int_enum[k]}, else: :error
        end

        def cast(_k), do: :error

        def load(k) when is_integer(k) do
          v = @int_enum[k]
          if v, do: {:ok, v}, else: :error
        end

        def dump(k) when is_atom(k), do: {:ok, @atom_enum[k]}

        def get_enum(), do: @atom_enum
      end
    end
  end
end