akkoma/lib/pleroma/web/plugs/set_locale_plug.ex

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# Pleroma: A lightweight social networking server
# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
# NOTE: this module is based on https://github.com/smeevil/set_locale
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defmodule Pleroma.Web.Plugs.SetLocalePlug do
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import Plug.Conn, only: [get_req_header: 2, assign: 3]
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def frontend_language_cookie_name, do: "userLanguage"
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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()
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|> Enum.find(&supported_locale?/1)
end
defp normalize_language_codes(codes) do
codes
|> Enum.map(fn code -> String.replace(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
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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)
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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