Move getFileNameFromURL helper method to URLUtil class

Author: Kaan0029

src/main/java/org/jabref/gui/externalfiles/ImportHandler.java

@@ -469,7 +469,7 @@ private List<BibEntry> handlePdfUrl(String pdfUrl) throws IOException {
             return List.of();
         }
         URLDownload urlDownload = new URLDownload(pdfUrl);
-        String filename = deriveFileNameFromUrl(pdfUrl);
+        String filename = URLUtil.getFileNameFromUrl(pdfUrl);
         Path targetFile = targetDirectory.get().resolve(filename);
         try {
             urlDownload.toFile(targetFile);
@@ -501,12 +501,4 @@ private List<BibEntry> handlePdfUrl(String pdfUrl) throws IOException {
             return List.of();
         }
     }
-
-    private String deriveFileNameFromUrl(String url) {
-        String fileName = url.substring(url.lastIndexOf('/') + 1);
-        if (fileName.isBlank()) {
-            fileName = "downloaded.pdf";
-        }
-        return FileUtil.getValidFileName(fileName);
-    }
 }

src/main/java/org/jabref/logic/util/URLUtil.java

@@ -9,6 +9,8 @@
 import java.util.Objects;
 import java.util.regex.Pattern;
 
+import org.jabref.logic.util.io.FileUtil;
+
 /**
  * URL utilities for URLs in the JabRef logic.
  * <p>
@@ -122,4 +124,19 @@ public static URI createUri(String url) {
             throw new IllegalArgumentException(e);
         }
     }
+
+    /**
+     * Extracts the filename from a URL.
+     * If the URL doesn't have a filename (ends with '/'), returns a default name.
+     *
+     * @param url the URL string to extract the filename from
+     * @return the extracted filename or a default name if none found
+     */
+    public static String getFileNameFromUrl(String url) {
+        String fileName = url.substring(url.lastIndexOf('/') + 1);
+        if (fileName.isBlank()) {
+            fileName = "downloaded.pdf";
+        }
+        return FileUtil.getValidFileName(fileName);
+    }
 }