- export untitled notes as 'Untitled' based on the language

- export notes with duplicate title as '<title> (<index>)'

browser/main/lib/dataApi/getFilename.js

@@ -0,0 +1,37 @@
+import filenamify from 'filenamify'
+import i18n from 'browser/lib/i18n'
+import path from 'path'
+
+/**
+ * @param {Object} note
+ * @param {String} fileType
+ * @param {String} directory
+ * @param {Object} deduplicator
+ *
+ * @return {String}
+ */
+
+function getFilename(note, fileType, directory, deduplicator) {
+  const basename = note.title
+    ? filenamify(note.title, { replacement: '_' })
+    : i18n.__('Untitled')
+
+  if (deduplicator) {
+    if (deduplicator[basename]) {
+      const filename = path.join(
+        directory,
+        `${basename} (${deduplicator[basename]}).${fileType}`
+      )
+
+      ++deduplicator[basename]
+
+      return filename
+    } else {
+      deduplicator[basename] = 1
+    }
+  }
+
+  return path.join(directory, `${basename}.${fileType}`)
+}
+
+module.exports = getFilename