print cli message if file already downloaded

pytube/cli.py

@@ -223,6 +223,11 @@ def _download(
 ) -> None:
     filesize_megabytes = stream.filesize // 1048576
     print(f"{stream.default_filename} | {filesize_megabytes} MB")
+    file_path = stream.get_file_path(filename=filename, output_path=target)
+    if stream.exists_at_path(file_path):
+        print(f"Already downloaded at:\n{file_path}")
+        return
+
     stream.download(output_path=target, filename=filename)
     sys.stdout.write("\n")
 

pytube/streams.py

@@ -215,22 +215,11 @@ class Stream:
         :rtype: str
 
         """
-        if filename:
-            filename = f"{safe_filename(filename)}.{self.subtype}"
-        else:
-            filename = self.default_filename
-
-        if filename_prefix:
-            filename = f"{safe_filename(filename_prefix)}{filename}"
-
-        file_path = os.path.join(target_directory(output_path), filename)
+        file_path = self.get_file_path(
+            filename=filename, output_path=output_path, filename_prefix=filename_prefix
+        )
 
-        if (
-            skip_existing
-            and os.path.isfile(file_path)
-            and os.path.getsize(file_path) == self.filesize
-        ):
-            # likely the same file, so skip it
+        if skip_existing and self.exists_at_path(file_path):
             logger.debug("file %s already exists, skipping", file_path)
             self.on_complete(file_path)
             return file_path
@@ -249,6 +238,23 @@ class Stream:
         self.on_complete(file_path)
         return file_path
 
+    def get_file_path(
+        self,
+        filename: Optional[str],
+        output_path: Optional[str],
+        filename_prefix: Optional[str] = None,
+    ) -> str:
+        if filename:
+            filename = f"{safe_filename(filename)}.{self.subtype}"
+        else:
+            filename = self.default_filename
+        if filename_prefix:
+            filename = f"{safe_filename(filename_prefix)}{filename}"
+        return os.path.join(target_directory(output_path), filename)
+
+    def exists_at_path(self, file_path: str) -> bool:
+        return os.path.isfile(file_path) and os.path.getsize(file_path) == self.filesize
+
     def stream_to_buffer(self) -> io.BytesIO:
         """Write the media stream to buffer
 

tests/test_cli.py

@@ -28,6 +28,7 @@ def test_download_when_itag_not_found(youtube, display_streams):
 @mock.patch("pytube.Stream")
 def test_download_when_itag_is_found(youtube, stream):
     stream.itag = 123
+    stream.exists_at_path.return_value = False
     youtube.streams = StreamQuery([stream])
     with patch.object(
         youtube.streams, "get_by_itag", wraps=youtube.streams.get_by_itag