From e9b8e403daf7373e11b29fd56096bf77dfabe223 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Pol=C3=A1k?= <456647@muni.cz>
Date: Sun, 17 Sep 2023 15:08:42 +0200
Subject: [PATCH] Initial draft of i18n API

---
 bundle.js            |  1 +
 site/i18n.js         | 71 ++++++++++++++++++++++++++++++++++++++++++++
 site/index.js        | 13 ++++++++
 site/locales/cs.json |  0
 site/locales/de.json |  0
 site/locales/en.json |  0
 6 files changed, 85 insertions(+)
 create mode 100755 site/i18n.js
 create mode 100755 site/locales/cs.json
 create mode 100755 site/locales/de.json
 create mode 100755 site/locales/en.json

diff --git a/bundle.js b/bundle.js
index 76af6a0..b33f61f 100755
--- a/bundle.js
+++ b/bundle.js
@@ -23,6 +23,7 @@ function replaceFileContents(string, fileDir) {
     const pattern = /%%([^%]+)%%|\/\/\s*include\s*"([^"]+)"/g;
 
     return string.replace(pattern, (_, filename1, filename2) => {
+        if (filename2 != null) console.error("include is used!!!!!");
         const filename = filename1 || filename2;
         const filenamePath = path.join(fileDir, filename);
         try {
diff --git a/site/i18n.js b/site/i18n.js
new file mode 100755
index 0000000..ee2e330
--- /dev/null
+++ b/site/i18n.js
@@ -0,0 +1,71 @@
+// Internationalization support
+// This file is used both serverside and clientside.
+
+/**
+ * Supported languages and their translations.
+ * Each file contains an object with key-value pairs.
+ *
+ * Argument substitution is supported through named arguments: translate("Hello {{name}}", {name: "World"})
+ *
+ * Plurals and arrays are currently not supported.
+ *
+ * If the key is missing in the current localization, it falls back to default localization
+ * and then to treating the key itself as the localization.
+ */
+
+const translations = {
+    cs: require("./locales/cs.json"),
+    de: require("./locales/de.json"),
+    en: require("./locales/en.json"),
+};
+/**
+ * @type {string[]}
+ */
+const locales = Object.keys(locales);
+const defaultLocale = "de";
+
+/** The currently selected locale. */
+var currentLocale = defaultLocale;
+
+/**
+ * Set the globally used locale.
+ * Expects a 2 character language code string, one from locales.
+ */
+function setLocale(locale) {
+    if (Object.hasOwn(locales, locale)) {
+        currentLocale = locale;
+        return true;
+    }
+    console.error("Attempted to setLocale to unsupported language: ", locale);
+    return false;
+}
+
+/**
+ * @param {string} key to translate
+ * @param {Object?} args arguments to substitute into the translated key
+ * @returns translated string
+ */
+function translate(key, args) {
+    let translation = locales[currentLocale][key];
+    if (translation === undefined) {
+        console.error("Untranslated key in ", currentLocale, ": ", key);
+        if (currentLocale != defaultLocale) {
+            translation = locales[defaultLocale][key] || key;
+        } else {
+            translation = key;
+        }
+    }
+
+    if (typeof args === "object") {
+        // Do argument substitution
+        for (const arg in args) {
+            translation = translation.replaceAll("{{" + arg + "}}", args[arg]);
+        }
+    }
+
+    return translation;
+}
+
+exports.setLocale = setLocale;
+exports.locales = locales;
+exports.translate = translate;
diff --git a/site/index.js b/site/index.js
index db47adf..b2315ec 100644
--- a/site/index.js
+++ b/site/index.js
@@ -6,11 +6,24 @@ const { STORE_KEYS } = require("./model/stores");
 const { ProgressBar } = require("./views/progress-bar");
 const progressBar = new ProgressBar(STORE_KEYS.length);
 
+const i18n = require("./i18n");
+
 (async () => {
     if (location.href.includes("heissepreise.github.io")) {
         location.href = "https://heisse-preise.io";
     }
 
+    // Find the most preferred supported language
+    for (const langCode in navigator.languages) {
+        // We don't do regional codes, so take just the language code
+        let lang = langCode.length >= 2 ? langCode.substring(0, 2) : null;
+        if (lang == null) continue;
+        if (i18n.locales.indexOf(lang) != -1) {
+            i18n.setLocale(lang);
+            break;
+        }
+    }
+
     await model.load(() => progressBar.addStep());
     const itemsFilter = document.querySelector("items-filter");
     const itemsList = document.querySelector("items-list");
diff --git a/site/locales/cs.json b/site/locales/cs.json
new file mode 100755
index 0000000..e69de29
diff --git a/site/locales/de.json b/site/locales/de.json
new file mode 100755
index 0000000..e69de29
diff --git a/site/locales/en.json b/site/locales/en.json
new file mode 100755
index 0000000..e69de29