Tighten body-tag auto-direction injection edge handling

Agent-Logs-Url: https://github.com/ArcaneChat/android/sessions/7f55ea69-ba6c-40ad-a72e-3080ac96b847

Co-authored-by: adbenitez <24558636+adbenitez@users.noreply.github.com>

src/main/java/org/thoughtcrime/securesms/FullMsgActivity.java

@@ -15,6 +15,7 @@ import chat.delta.rpc.types.HttpResponse;
 import com.b44t.messenger.DcContext;
 import java.io.ByteArrayInputStream;
 import java.lang.ref.WeakReference;
+import java.util.Locale;
 import org.thoughtcrime.securesms.connect.DcHelper;
 import org.thoughtcrime.securesms.util.DynamicTheme;
 import org.thoughtcrime.securesms.util.JsonUtils;
@@ -120,6 +121,7 @@ public class FullMsgActivity extends WebViewActivity {
           try {
             FullMsgActivity activity = activityReference.get();
             String html = activity.dcContext.getMsgHtml(activity.msgId);
+            html = withAutoTextDirection(html);
 
             activity.runOnUiThread(
                 () -> {
@@ -141,6 +143,31 @@ public class FullMsgActivity extends WebViewActivity {
         });
   }
 
+  private static String withAutoTextDirection(String html) {
+    if (html == null || html.isEmpty()) {
+      return html;
+    }
+    String lowercaseHtml = html.toLowerCase(Locale.US);
+    int bodyTagStart = lowercaseHtml.indexOf("<body");
+    if (bodyTagStart >= 0) {
+      int bodyTagEnd = lowercaseHtml.indexOf(">", bodyTagStart);
+      if (bodyTagEnd < 0) {
+        return html;
+      }
+      String bodyTag = html.substring(bodyTagStart, bodyTagEnd + 1);
+      String lowercaseBodyTag = lowercaseHtml.substring(bodyTagStart, bodyTagEnd + 1);
+      if (lowercaseBodyTag.contains("dir=")) {
+        return html;
+      }
+      if (lowercaseBodyTag.endsWith("/>")) {
+        return html;
+      }
+      String updatedBodyTag = bodyTag.substring(0, bodyTag.length() - 1) + " dir=\"auto\">";
+      return html.substring(0, bodyTagStart) + updatedBodyTag + html.substring(bodyTagEnd + 1);
+    }
+    return "<div dir=\"auto\">" + html + "</div>";
+  }
+
   @Override
   protected void onPause() {
     super.onPause();