Enhance logic for determining the files to `download()`

* if the `interactive` flag is set, actually query the user
* if it's just a single file anyway, just download that

vre_repository_connector/auto.py

@@ -117,12 +117,27 @@ def download(
 
     # if we couldn't determine a file from the URL...
     if fid is None:
-        if all:
+        avail_files = list(service.list_files(cid))
+        if len(avail_files) == 1:
+            fid = avail_files[0]
+
+        elif all:
             # we either take all of them
-            fids = list(service.list_files(cid))
+            fids = avail_files
+
         elif interactive:
-            # or we ask the user (TODO)
-            pass
+            # or we ask the user
+            selection = 0
+            for idx, file_ in enumerate(avail_files):
+                print(f"{idx+1}) {file_}")
+
+            while not (0 < selection <= len(avail_files)):
+                try:
+                    selection = int(input(f"Select [1-{len(avail_files)}]: "))
+                except ValueError:
+                    selection = 0
+
+            fid = avail_files[selection - 1]
         else:
             # or we give up
             return None