akkoma/lib/pleroma/web/plugs/set_locale_plug.ex
Tusooa Zhu ef73f61b07 Fallback to a variant if the language in general is not supported
For an example, here, zh is not supported, but zh_Hans and zh_Hant
are. If the user asks for zh, we should choose a variant for them
instead of fallbacking to default.

Some browsers (e.g. Firefox) does not allow users to customize
their language codes. For example, there is no zh-Hans, but only
zh, zh-CN, zh-TW, zh-HK, etc. This provides a workaround for
those users suffering from bad design decisions.
2022-06-29 20:47:10 +01:00

95 lines
2.4 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2021 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 Pleroma.Web.Plugs.SetLocalePlug do
import Plug.Conn, only: [get_req_header: 2, assign: 3]
def frontend_language_cookie_name, do: "userLanguage"
def init(_), do: nil
def call(conn, _) do
locale = get_locale_from_header(conn) || Gettext.get_locale()
Gettext.put_locale(locale)
assign(conn, :locale, locale)
end
defp get_locale_from_header(conn) do
conn
|> extract_preferred_language()
|> normalize_language_codes()
|> first_supported()
end
defp first_supported(locales) do
locales
|> Enum.flat_map(&Pleroma.Web.Gettext.supported_variants_of_locale/1)
|> Enum.find(&supported_locale?/1)
end
defp normalize_language_codes(codes) do
codes
|> Enum.map(fn code -> Pleroma.Web.Gettext.normalize_locale(code) end)
end
defp extract_preferred_language(conn) do
extract_frontend_language(conn) ++ extract_accept_language(conn)
end
defp extract_frontend_language(conn) do
%{req_cookies: cookies} =
conn
|> Plug.Conn.fetch_cookies()
case cookies[frontend_language_cookie_name()] do
nil ->
[]
fe_lang ->
[fe_lang]
|> ensure_language_fallbacks()
end
end
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
defp supported_locale?(locale) do
Pleroma.Web.Gettext.supports_locale?(locale)
end
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
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