Replace is_tweet() with a check on content type

tildes/tildes/lib/url.py

@@ -17,9 +17,3 @@ def get_domain_from_url(url: str, strip_www: bool = True) -> str:
         domain = domain[4:]
 
     return domain
-
-
-def is_tweet(url: str) -> bool:
-    """Return whether a url is a link to a tweet."""
-    domain = get_domain_from_url(url)
-    return domain == "twitter.com" and "/status/" in url

tildes/tildes/models/topic/topic.py

@@ -32,7 +32,7 @@ from tildes.lib.datetime import utc_from_timestamp, utc_now
 from tildes.lib.id import id_to_id36
 from tildes.lib.markdown import convert_markdown_to_safe_html
 from tildes.lib.string import convert_to_url_slug
-from tildes.lib.url import get_domain_from_url, is_tweet
+from tildes.lib.url import get_domain_from_url
 from tildes.metrics import incr_counter
 from tildes.models import DatabaseModel
 from tildes.models.group import Group
@@ -492,7 +492,7 @@ class Topic(DatabaseModel):
         if self.is_text_type:
             return self.get_content_metadata("excerpt")
 
-        if self.link and is_tweet(self.link):
+        if self.content_type is TopicContentType.TWEET:
             authors = self.get_content_metadata("authors")
             tweet = self.get_content_metadata("description")
 
@@ -515,7 +515,7 @@ class Topic(DatabaseModel):
         if not self.is_link_type:
             return None
 
-        if self.link and is_tweet(self.link):
+        if self.content_type is TopicContentType.TWEET:
             authors = self.get_content_metadata("authors")
             tweet = self.get_content_metadata("description")