defmodule EctoGettext do
  @moduledoc """
  EctoGettext - library for localization Ecto validation errors with using Gettext

  ### Example:

    import EctoGettext

    localize_validations(MyApp.Gettext, errors)
  """

  @doc """
  Get a list of errors and return a new list with translated errors
  """
  @spec localize_validations(module, list) :: list

  def localize_validations(module, errors) do
    errors
    |> Enum.map(fn elem -> localize(module, elem) end)
  end

  defp localize(module, error) do
    {attr, message} = error
    {Gettext.dgettext(module, "attributes", Atom.to_string(attr)), set_message(module, message)}
  end

  defp numbers, do: ~w(1 2 3 4 5 6 7 8 9)

  defp set_message(module, message) do
    message = String.downcase(message)

    cond do
      String.starts_with?(message, "should be") ->
        Gettext.dgettext(module, "errors", format_message(message), count: parse_number(message))
      true ->
        Gettext.dgettext(module, "errors", message)
    end
  end

  defp format_message(message) do
    message
    |> String.graphemes
    |> Enum.filter(fn elem -> !Enum.member?(numbers, elem) end)
    |> Enum.join
    |> String.split(" ", trim: true)
    |> List.insert_at(4, "%{count}")
    |> Enum.join(" ")
  end

  defp parse_number(message) do
    message
    |> String.graphemes
    |> Enum.filter(fn elem -> Enum.member?(numbers, elem) end)
    |> Enum.join
    |> String.to_integer
  end
end