# Portions of this file are derived from Pleroma: # Pleroma: A lightweight social networking server # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/> # SPDX-License-Identifier: AGPL-3.0-only # NOTE: this module is based on https://github.com/smeevil/set_locale defmodule Mobilizon.Web.Plugs.DetectLocalePlug do @moduledoc """ Plug to set locale for Gettext """ import Plug.Conn, only: [get_req_header: 2, assign: 3] alias Mobilizon.Web.Gettext, as: GettextBackend @spec init(any()) :: any() def init(_), do: nil @spec call(Plug.Conn.t(), Keyword.t()) :: Plug.Conn.t() def call(conn, _) do locale = get_locale_from_header(conn) assign(conn, :detected_locale, locale) end @spec get_locale_from_header(Plug.Conn.t()) :: String.t() defp get_locale_from_header(conn) do conn |> extract_accept_language() |> Enum.find(&supported_locale?/1) end @spec extract_accept_language(Plug.Conn.t()) :: list(String.t()) defp extract_accept_language(conn) do case get_req_header(conn, "accept-language") do [value | _] -> value |> String.split(",") |> Enum.map(&parse_language_option/1) |> Enum.sort(&(&1.quality > &2.quality)) |> Enum.map(& &1.tag) |> Enum.reject(&is_nil/1) |> ensure_language_fallbacks() _ -> [] end end @spec supported_locale?(String.t()) :: boolean() defp supported_locale?(locale) do GettextBackend |> Gettext.known_locales() |> Enum.member?(locale) end @spec parse_language_option(String.t()) :: %{tag: String.t(), quality: float()} defp parse_language_option(string) do captures = Regex.named_captures(~r/^\s?(?<tag>[\w\-]+)(?:;q=(?<quality>[\d\.]+))?$/i, string) quality = case Float.parse(captures["quality"] || "1.0") do {val, _} -> val :error -> 1.0 end %{tag: captures["tag"], quality: quality} end @spec ensure_language_fallbacks(list(String.t())) :: list(String.t()) defp ensure_language_fallbacks(tags) do Enum.flat_map(tags, fn tag -> [language | _] = String.split(tag, "-") if Enum.member?(tags, language), do: [tag], else: [tag, language] end) end end