add language functionality

src/main.rs

@@ -2,7 +2,7 @@ use crate::model::client::Client;
 use axum::{http::HeaderMap, routing::get, Router};
 use axum_extra::extract::{cookie::Cookie, CookieJar};
 use sqlx::{pool::PoolOptions, sqlite::SqliteConnectOptions, SqlitePool};
-use std::{str::FromStr, sync::Arc};
+use std::{fmt::Display, str::FromStr, sync::Arc};
 use tower_http::services::ServeDir;
 use uuid::Uuid;
 
@@ -28,7 +28,23 @@ enum Language {
     English,
 }
 
+impl Display for Language {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Language::German => f.write_str("de"),
+            Language::English => f.write_str("en"),
+        }
+    }
+}
+
 impl Language {
+    pub(crate) fn next_language(&self) -> Self {
+        match self {
+            Language::German => Language::English,
+            Language::English => Language::German,
+        }
+    }
+
     fn to_locale(&self) -> &'static str {
         match self {
             Language::German => "de",