Merge branch 'newest-reply-sorting-option' into 'master'

Add a newest reply/newest leaf sorting method for comments

Closes #111

See merge request tildes/tildes!150

tildes/tildes/enums.py

@@ -45,6 +45,7 @@ class CommentTreeSortOption(enum.Enum):
     NEWEST = enum.auto()
     POSTED = enum.auto()
     RELEVANCE = enum.auto()
+    NEWEST_REPLY = enum.auto()
 
     @property
     def description(self) -> str:
@@ -55,6 +56,8 @@ class CommentTreeSortOption(enum.Enum):
             return "order posted"
         elif self.name == "RELEVANCE":
             return "relevance"
+        elif self.name == "NEWEST_REPLY":
+            return "newest reply"
 
         return "most {}".format(self.name.lower())
 

tildes/tildes/models/comment/comment_tree.py

@@ -92,6 +92,13 @@ class CommentTree:
                 comment.depth = 0
                 self.tree.append(comment)
 
+    @staticmethod
+    def _first_bottommost_reply(comment: Comment) -> Comment:
+        """Continuously gets the first reply from a comment until there is no more."""
+        while comment.replies:
+            comment = comment.replies[0]
+        return comment
+
     @staticmethod
     def _sort_tree(tree: list[Comment], sort: CommentTreeSortOption) -> list[Comment]:
         """Sort the tree by the desired ordering (recursively).
@@ -100,6 +107,15 @@ class CommentTree:
         compare equal on the sorting method will be the same as the order that they were
         originally in when passed to this function.
         """
+        # sort the tree's comments first, this will be important when sorting by newest
+        # reply
+        for comment in tree:
+            if not comment.has_visible_descendant:
+                # no need to bother sorting replies if none will be visible
+                continue
+
+            comment.replies = CommentTree._sort_tree(comment.replies, sort)
+
         if sort == CommentTreeSortOption.NEWEST:
             tree = sorted(tree, key=lambda c: c.created_time, reverse=True)
         elif sort == CommentTreeSortOption.POSTED:
@@ -108,13 +124,16 @@ class CommentTree:
             tree = sorted(tree, key=lambda c: c.num_votes, reverse=True)
         elif sort == CommentTreeSortOption.RELEVANCE:
             tree = sorted(tree, key=lambda c: c.relevance_sorting_value, reverse=True)
-
-        for comment in tree:
-            if not comment.has_visible_descendant:
-                # no need to bother sorting replies if none will be visible
-                continue
-
-            comment.replies = CommentTree._sort_tree(comment.replies, sort)
+        elif sort == CommentTreeSortOption.NEWEST_REPLY:
+            # sort by the creation time of the first bottom-most reply in the
+            # entire tree, or the comment itself if there are no replies.
+            # the comment's first bottom-most reply is the newest reply since
+            # it has been sorted above
+            tree = sorted(
+                tree,
+                key=lambda c: CommentTree._first_bottommost_reply(c).created_time,
+                reverse=True,
+            )
 
         return tree