Add default flag emoji display names

public/scripts/send-ws-messages.js

@@ -81,3 +81,31 @@ document.addEventListener('htmx:wsConfigSend', function (e) {
     };
   }
 });
+
+// Set the user's name to their flag by default
+document.body.addEventListener('htmx:wsOpen', function (evt) {
+  const locale = navigator.language || navigator.userLanguage;
+  const countryCode = locale.split('-')[1] || locale.split('_')[1] || locale;
+  const countryCodeToFlagEmoji = (code) => {
+    if (code.length === 2) {
+      return code
+        .toUpperCase()
+        .split('')
+        .map((char) => String.fromCodePoint(127397 + char.charCodeAt(0)))
+        .join('');
+    }
+    return null;
+  };
+  const flagEmoji = countryCodeToFlagEmoji(countryCode);
+
+  if (flagEmoji) {
+    const message = {
+      type: 'update_display_name',
+      displayName: flagEmoji,
+    };
+    evt.detail.socketWrapper.send(JSON.stringify(message));
+
+    const displayNameSpan = document.getElementById('display-name');
+    displayNameSpan.textContent = flagEmoji;
+  }
+});