Fix channel url matching. (#1005)

* Fixes channel url matching for channels without canonical names.

pytube/contrib/channel.py

@@ -14,10 +14,10 @@ class Channel(Playlist):
     def __init__(self, url: str, proxies: Optional[Dict[str, str]] = None):
         super().__init__(url, proxies)
 
-        self.channel_name = extract.channel_name(url)
+        self.channel_uri = extract.channel_name(url)
 
         self.channel_url = (
-            f"https://www.youtube.com/c/{self.channel_name}"
+            f"https://www.youtube.com{self.channel_uri}"
         )
         self.videos_url = self.channel_url + '/videos'
         self.playlists_url = self.channel_url + '/playlists'

pytube/extract.py

@@ -195,16 +195,17 @@ def channel_name(url: str) -> str:
         YouTube channel name.
     """
     patterns = [
-        r"(?:\/c\/([\d\w_\-]+)(\/.*)?)",
-        r"(?:\/channel\/([\w\d_\-]+)(\/.*)?)"
+        r"(?:\/(c)\/([\d\w_\-]+)(\/.*)?)",
+        r"(?:\/(channel)\/([\w\d_\-]+)(\/.*)?)"
     ]
     for pattern in patterns:
         regex = re.compile(pattern)
         function_match = regex.search(url)
         if function_match:
             logger.debug("finished regex search, matched: %s", pattern)
-            channel_id = function_match.group(1)
-            return channel_id
+            uri_style = function_match.group(1)
+            uri_identifier = function_match.group(2)
+            return f'/{uri_style}/{uri_identifier}'
 
     raise RegexMatchError(
         caller="channel_name", pattern="patterns"

tests/contrib/test_channel.py

@@ -20,7 +20,7 @@ def test_channel_name(request_get, channel_videos_html):
     request_get.return_value = channel_videos_html
 
     c = Channel('https://www.youtube.com/c/ProgrammingKnowledge/videos')
-    assert c.channel_name == 'ProgrammingKnowledge'
+    assert c.channel_uri == '/c/ProgrammingKnowledge'
 
 
 @mock.patch('pytube.request.get')