Implement i18n backend

src/i18n.rs

@@ -0,0 +1,55 @@
+use std::{collections::HashMap, fs::{self, File}, io::BufReader, process::Command};
+use derive_more::From;
+use rocket_dyn_templates::tera::{self, Value};
+
+use gettext::Catalog;
+
+#[derive(From, Debug)]
+pub enum LoadCatalogsError {
+    Io(std::io::Error),
+    Parse(gettext::Error),
+    MissingDefaultLanguage,
+}
+
+const DEFAULT: &str = "ja";
+
+pub fn load_catalogs() -> Result<HashMap<String, Catalog>, LoadCatalogsError> {
+    let mut catalogs = HashMap::new();
+    for file in fs::read_dir("i18n")? {
+        let file = file?;
+        let path = file.path();
+        if !file.file_type()?.is_file() || !path.extension().map(|extension| extension.eq("po")).unwrap_or(false) {
+            continue;
+        }
+        let language_code = path
+            .file_stem()
+            .expect("Invalid translation file name")
+            .to_string_lossy()
+            .to_string();
+        let po_file_path = path;
+        let mo_file_path = format!("i18n/{}.mo", language_code);
+        Command::new("msgfmt")
+            .arg(&po_file_path)
+            .arg("-o")
+            .arg(&mo_file_path)
+            .output()?;
+        catalogs.insert(language_code, Catalog::parse(BufReader::new(File::open(mo_file_path)?))?);
+    }
+    if !catalogs.contains_key(DEFAULT) {
+        return Err(LoadCatalogsError::MissingDefaultLanguage);
+    }
+    Ok(catalogs)
+}
+
+pub fn i18n_filter(value: &Value, _args: &HashMap<String, Value>, catalogs: &HashMap<String, Catalog>) -> tera::Result<Value> {
+    let key = value.as_str().ok_or_else(|| {
+        tera::Error::msg("The translation key must be a string")
+    })?;
+
+    let translation = catalogs
+        .get(DEFAULT)
+        .expect("Missing catalog")
+        .gettext(key);
+
+    Ok(Value::String(translation.to_owned()))
+}

src/main.rs

@@ -3,9 +3,9 @@ extern crate rocket;
 
 use poise::serenity_prelude::Http;
 use rocket::fs::{relative, FileServer};
-use rocket_dyn_templates::Template;
+use rocket_dyn_templates::{Template, tera};
 use sass_rocket_fairing::SassFairing;
-use std::env;
+use std::{env, collections::HashMap};
 
 mod models;
 use models::Settings;
@@ -17,6 +17,9 @@ mod cookies;
 mod routes;
 use routes::*;
 
+mod i18n;
+use i18n::{load_catalogs, i18n_filter};
+
 mod prelude;
 
 #[launch]
@@ -40,6 +43,12 @@ async fn rocket() -> _ {
             routes![get_challenge, login, post_login, success, logout, testing],
         )
         .mount("/css", FileServer::from(relative!("styles/css")))
-        .attach(Template::fairing())
+        .attach(Template::custom(|engines| {
+            use tera::Value;
+            let catalogs = load_catalogs().unwrap();
+            engines.tera.register_filter("i18n", move |value: &Value, args: &HashMap<String, Value>| {
+                i18n_filter(value, args, &catalogs)
+            })
+        }))
         .attach(SassFairing::default())
-}
+}

src/routes/get_challenge.rs

@@ -7,12 +7,6 @@ use crate::models::{Challenge, User, Settings};
 
 #[get("/<challenge>")]
 pub async fn get_challenge(challenge: u32, cookies: &CookieJar<'_>, settings: &State<Settings>) -> Template {
-    println!(
-        "{:?}",
-        cookies
-            .get_private("user_name")
-            .map(|cookie| cookie.value().to_owned())
-    );
     Template::render(
         "index",
         context! {