mas_handlers/
preferred_language.rs

1// Copyright 2025, 2026 Element Creations Ltd.
2// Copyright 2024, 2025 New Vector Ltd.
3// Copyright 2023, 2024 The Matrix.org Foundation C.I.C.
4//
5// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
6// Please see LICENSE files in the repository root for full details.
7
8use std::{convert::Infallible, future::ready, sync::Arc};
9
10use axum::{
11    extract::{FromRef, FromRequestParts},
12    http::request::Parts,
13};
14use headers::HeaderMapExt as _;
15use mas_axum_utils::language_detection::AcceptLanguage;
16use mas_i18n::{DataLocale, Translator, locale};
17
18pub struct PreferredLanguage(pub DataLocale);
19
20impl<S> FromRequestParts<S> for PreferredLanguage
21where
22    S: Send + Sync,
23    Arc<Translator>: FromRef<S>,
24{
25    type Rejection = Infallible;
26
27    fn from_request_parts(
28        parts: &mut Parts,
29        state: &S,
30    ) -> impl Future<Output = Result<Self, Self::Rejection>> + Send {
31        let translator: Arc<Translator> = FromRef::from_ref(state);
32        let accept_language = parts.headers.typed_get::<AcceptLanguage>();
33
34        let iter = accept_language
35            .iter()
36            .flat_map(AcceptLanguage::iter)
37            .flat_map(|lang| {
38                let lang = DataLocale::from(lang);
39                // XXX: this is hacky as we may want to actually maintain proper language
40                // aliases at some point, but `zh-CN` doesn't fallback
41                // automatically to `zh-Hans`, so we insert it manually here.
42                // For some reason, `zh-TW` does fallback to `zh-Hant` correctly.
43                if lang == locale!("zh-CN").into() {
44                    vec![lang, locale!("zh-Hans").into()]
45                } else {
46                    vec![lang]
47                }
48            });
49
50        let locale = translator.choose_locale(iter);
51
52        ready(Ok(PreferredLanguage(locale)))
53    }
54}
mas_handlers/preferred_language.rs

mas_handlers/
preferred_language.rs
