OpenAI: refactoring

app/src/main/java/eu/faircode/email/OpenAI.java

@@ -229,6 +229,18 @@ public class OpenAI {
         }
     }
 
+    static String truncateParagraphs(@NonNull String text, int maxlen) {
+        String[] paragraphs = text.split("[\\r\\n]+");
+
+        int i = 0;
+        StringBuilder sb = new StringBuilder();
+        while (i < paragraphs.length &&
+                sb.length() + paragraphs[i].length() + 1 < maxlen)
+            sb.append(paragraphs[i++]).append('\n');
+
+        return sb.toString();
+    }
+
     static class Message {
         private final String role; //  // system, user, assistant
         private final String content;