feat: add profile language preferences and refine toast, dropdown and history UI

src/auth/mod.rs

@@ -51,6 +51,7 @@ pub struct User {
     pub confirmed_at: Option<String>,
     pub is_active: i64,
     pub theme: String,
+    pub language: String,
 }
 
 #[derive(Deserialize)]
@@ -99,6 +100,8 @@ pub struct ProfileUpdateRequest {
     editor_color: Option<String>,
     #[serde(default)]
     theme: Option<String>,
+    #[serde(default)]
+    language: Option<String>,
 }
 #[derive(Deserialize)]
 pub struct DeleteAccountRequest {
@@ -252,6 +255,7 @@ impl<'r> sqlx::FromRow<'r, AnyRow> for User {
             confirmed_at: crate::row_decode::optional_text(row, "confirmed_at")?,
             is_active: row.try_get("is_active")?,
             theme: crate::row_decode::text(row, "theme")?,
+            language: crate::row_decode::text(row, "language")?,
         })
     }
 }
@@ -367,6 +371,7 @@ pub struct SessionResponse {
     suggested_nickname: Option<String>,
     editor_color: Option<String>,
     theme: String,
+    language: String,
 }
 #[derive(Serialize)]
 pub struct IdentityResponse {
@@ -380,6 +385,7 @@ pub struct RegisterResponse {
     expires_at: Option<String>,
     confirmation_required: bool,
     theme: String,
+    language: String,
     message: String,
 }
 
@@ -531,6 +537,7 @@ pub async fn register(
                 expires_at: None,
                 confirmation_required: true,
                 theme: user.theme,
+                language: user.language,
                 message:
                     "Account created. Check your e-mail and confirm the account before logging in."
                         .into(),
@@ -550,6 +557,7 @@ pub async fn register(
             expires_at: Some(session.expires_at),
             confirmation_required: false,
             theme: session.theme,
+            language: session.language,
             message: "Account created.".into(),
         }),
     )
@@ -845,6 +853,7 @@ pub async fn me(
             suggested_nickname,
             editor_color,
             theme: user.theme,
+            language: user.language,
         },
         state.user_session_ttl_days,
     ))
@@ -972,11 +981,24 @@ pub async fn update_profile(
             .map_err(AuthError::database)?;
     }
 
+    let mut language = user.language.clone();
+    if let Some(value) = req.language.as_deref() {
+        language = validate_language(value)?.to_owned();
+        sqlx::query(queries::get(state.db.kind(), queries::AUTH_UPDATE_LANGUAGE))
+            .bind(&language)
+            .bind(Utc::now().to_rfc3339())
+            .bind(user.id)
+            .execute(state.db.pool())
+            .await
+            .map_err(AuthError::database)?;
+    }
+
     Ok(Json(serde_json::json!({
         "ok": true,
         "nickname": nickname,
         "editor_color": req.editor_color.as_deref(),
         "theme": theme,
+        "language": language,
         "email_pending": email_pending,
         "message": if email_pending {
             "Profile updated. Confirm the new e-mail address using the link sent to it."
@@ -2560,6 +2582,7 @@ async fn create_session(state: &SharedState, user: &User) -> Result<SessionRespo
         suggested_nickname,
         editor_color,
         theme: user.theme.clone(),
+        language: user.language.clone(),
     })
 }
 async fn find_user_by_nickname(
@@ -2620,6 +2643,11 @@ fn validate_theme(value: &str) -> Result<&str, AuthError> {
     }
 }
 
+fn validate_language(value: &str) -> Result<&'static str, AuthError> {
+    crate::i18n::canonical_code(value)
+        .ok_or_else(|| AuthError::bad_request("Unknown interface language."))
+}
+
 fn validate_editor_color(value: &str) -> Result<String, AuthError> {
     let value = value.trim();
     if value.len() == 7