reddit: handle post and comment links in one regex

It's entirely impractical to try to handle post and comment links in
separate callables, because comment links contain an entire post link.

Before, this was handled by anchoring the post URL pattern at the end,
but that broke Sopel handling e.g. `?sort=confidence` if someone sorted
the comments before copying the link into IRC.

Lookaround assertions didn't appear to prevent matching the post link
contained in every comment link, so this solution seemed like the only
way forward. It's a nice tidy dispatcher pattern, really.

sopel/modules/reddit.py

@@ -27,10 +27,13 @@
 
 domain = r'https?://(?:www\.|old\.|pay\.|ssl\.|[a-z]{2}\.)?reddit\.com'
 subreddit_url = r'%s/r/([\w-]+)/?$' % domain
-post_url = r'%s/r/\S+?/comments/([\w-]+)(?:/[\w%%]+)?/?' % domain
+post_or_comment_url = (
+    domain +
+    r'/r/\S+?/comments/(?P<submission>[\w-]+)'
+    r'(?:/?(?:[\w%]+/(?P<comment>[\w-]+))?)'
+)
 short_post_url = r'https?://redd\.it/([\w-]+)'
 user_url = r'%s/u(?:ser)?/([\w-]+)' % domain
-comment_url = r'%s/r/\S+?/comments/\S+?/\S+?/([\w-]+)' % domain
 image_url = r'https?://i\.redd\.it/\S+'
 video_url = r'https?://v\.redd\.it/([\w-]+)'
 gallery_url = r'https?://(?:www\.)?reddit\.com/gallery/([\w-]+)'
@@ -107,18 +110,25 @@ def video_info(bot, trigger, match):
         timeout=(10.0, 4.0)).headers['Location']
     try:
         return say_post_info(
-            bot, trigger, re.match(post_url, url).group(1), False, True)
+            bot, trigger, re.match(post_or_comment_url, url).group('submission'), False, True
+        )
     except AttributeError:
         # Fail silently if we can't map the video link to a submission
         return plugin.NOLIMIT
 
 
-@plugin.url(post_url)
+@plugin.url(post_or_comment_url)
 @plugin.url(short_post_url)
 @plugin.output_prefix(PLUGIN_OUTPUT_PREFIX)
-def rpost_info(bot, trigger, match):
+def post_or_comment_info(bot, trigger, match):
     match = match or trigger
-    return say_post_info(bot, trigger, match.group(1))
+    comment = match.group('comment')
+
+    if comment:
+        say_comment_info(bot, trigger, comment)
+        return
+
+    say_post_info(bot, trigger, match.group('submission'))
 
 
 @plugin.url(gallery_url)
@@ -205,12 +215,9 @@ def say_post_info(bot, trigger, id_, show_link=True, show_comments_link=False):
         return plugin.NOLIMIT
 
 
-@plugin.url(comment_url)
-@plugin.output_prefix(PLUGIN_OUTPUT_PREFIX)
-def comment_info(bot, trigger, match):
-    """Shows information about the linked comment"""
+def say_comment_info(bot, trigger, id_):
     try:
-        c = bot.memory['reddit_praw'].comment(match.group(1))
+        c = bot.memory['reddit_praw'].comment(id_)
     except prawcore.exceptions.NotFound:
         bot.reply('No such comment.')
         return plugin.NOLIMIT