Complete application localization across all supported languages

web-app.html

@@ -43,6 +43,7 @@
     <link data-trunk rel="copy-file" href="web/ocs-parse-worker.js" />
     <link data-trunk rel="copy-file" href="web/discussions.json" />
     <link data-trunk rel="copy-file" href="web/videos.json" />
+    <link data-trunk rel="copy-file" href="web/locale-labels.json" />
   </head>
   <body>
     <div id="loading">
@@ -53,6 +54,31 @@
     <script>
       (() => {
         const splash = document.getElementById("loading");
+        fetch("locale-labels.json").then(response => response.json()).then(labels => {
+          let saved;
+          try {
+            saved = JSON.parse(localStorage.getItem("opencadstudio.settings"))?.settings?.language;
+          } catch {}
+          const preferred = navigator.languages?.length ? navigator.languages : [navigator.language];
+          const requested = typeof saved === "string" && saved !== "system" ? [saved, ...preferred] : preferred;
+          const available = Object.keys(labels);
+          let locale = "en-US";
+          for (const candidate of requested) {
+            try {
+              const language = new Intl.Locale(candidate);
+              const match = available.find(value => value.toLowerCase() === language.baseName.toLowerCase())
+                || (language.language === "zh"
+                  ? (language.maximize().script === "Hant" ? "zh-TW" : "zh-CN")
+                  : available.find(value => value.startsWith(language.language + "-")));
+              if (match) { locale = match; break; }
+            } catch {}
+          }
+          document.title = labels[locale].title;
+          document.documentElement.lang = locale;
+          document.documentElement.dir = locale === "ar-SA" ? "rtl" : "ltr";
+          const caption = splash?.querySelector(".sub");
+          if (caption) caption.textContent = labels[locale].loading;
+        }).catch(() => {});
         const done = () => {
           if (!splash) return;
           splash.classList.add("hide");