Add basic comment permalink handling

README.md

@@ -63,6 +63,10 @@ If video "watch" links contain a playlist ID, the plugin will show the
 playlist info as well as the video info by default. To disable this, set
 `playlist_watch` to `False`.
 
+If video "watch" links contain a comment ID, the plugin will **only** show info
+about the comment by default. If you also want video info posted in this
+situation, set `comment_watch` to `True`.
+
 For videos, by default, only the video length, uploader (channel name), view
 count, and upload date are shown. The included items, and the order in which
 they appear, depend on the `info_items` setting, which is a list of keywords.

sopel_youtube/__init__.py

@@ -35,7 +35,13 @@
     r"((?:T)(?P<h>[0-9]+([,.][0-9]+)?H)?"
     r"(?P<m>[0-9]+([,.][0-9]+)?M)?"
     r"(?P<s>[0-9]+([,.][0-9]+)?S)?)?$")
-video_regex = re.compile(r'(?:youtube\.com/(?:watch\S*v=|shorts/|live/)|youtu\.be/)([\w-]+)')
+video_regex = re.compile(
+    r'''
+    (?:
+      (?:youtube\.com/(?:shorts/|live/)|youtu\.be/)(?P<video1>[\w-]+)|
+      youtube\.com/watch/?(?:\S*[?&]v=(?P<video2>[\w-]+)|\S*[?&]lc=(?P<comment>[\w_-]+))+
+    )
+    ''', re.VERBOSE)
 playlist_regex = re.compile(r'youtube\.com/(playlist|watch)\S*list=([\w-]+)')
 
 
@@ -97,6 +103,11 @@ class YoutubeSection(StaticSection):
     Whether to show playlist info if the list ID is embedded in a video watch link.
     """
 
+    comment_watch = BooleanAttribute('comment_watch', default=False)
+    """
+    Whether to also show video info when video ID is included in a comment link.
+    """
+
 
 def configure(config):
     config.define_section('youtube', YoutubeSection, validate=False)
@@ -107,7 +118,10 @@ def configure(config):
         "info_items", "Which attributes to show in response to video links"
     )
     config.youtube.configure_setting(
-        "playlist_watch", "Show playlist info if embedded in video links?"
+        "playlist_watch", "Show playlist info if included in a video link?"
+    )
+    config.youtube.configure_setting(
+        "comment_watch", "Show video info if included in a comment link?"
     )
 
 
@@ -179,7 +193,62 @@ def video_search(bot, trigger):
 def get_video_info(bot, trigger, match=None):
     """Get information about the linked YouTube video."""
     match = match or trigger
-    _say_video_result(bot, trigger, match.group(1), include_link=False)
+    comment = match.group('comment')
+    video = match.group('video1') or match.group('video2')
+
+    if comment:
+        _say_comment_result(bot, trigger, comment)
+        if not bot.settings.youtube.comment_watch:
+            return
+
+    if video:
+        _say_video_result(bot, trigger, video, include_link=False)
+
+
+def _say_comment_result(bot, trigger, id_):
+    for n in range(num_retries + 1):
+        try:
+            result = bot.memory['youtube_api_client'].comments().list(
+                id=id_,
+                part='id,snippet',
+                fields=
+                    'items('
+                        'snippet('
+                            'authorDisplayName,likeCount,publishedAt,textDisplay'
+                        ')'
+                    ')',
+                textFormat='plainText',
+            ).execute(http=httplib2.Http()).get('items')
+        except ConnectionError:
+            if n >= num_retries:
+                bot.say('Maximum retries exceeded fetching YouTube video {}, '
+                        'please try again later.'.format(id_))
+                return
+            sleep(random() * 2**n)
+            continue
+        except googleapiclient.errors.HttpError as e:
+            bot.say(_get_http_error_message(e))
+            return
+        except Exception as e:
+            # Catch-all, because enumerating all the possible exceptions is a waste of code lines
+            bot.say('Temporary error talking to YouTube: %s' % e)
+            return
+        break
+    if not result:
+        return
+    result = result[0]
+
+    # Formatting
+    snippet = result['snippet']
+    author = snippet['authorDisplayName']
+    likes = snippet['likeCount']
+    published = _format_datetime(bot, trigger, snippet["publishedAt"])
+    text = snippet['textDisplay']
+
+    message = '[YouTube] {author}: {text}'.format(author=author, text=text)
+    end = ' | 👍 {likes} | {date}'.format(likes=likes, date=published)
+
+    bot.say(message, truncation='…', trailing=end)
 
 
 def _say_video_result(bot, trigger, id_, include_link=True):