More thorough support for comment threading.

[zzz-floof.git] / floof / model / comments.py

diff --git a/floof/model/comments.py b/floof/model/comments.py
index e1ad150..bcfee9f 100644 (file)
--- a/floof/model/comments.py
+++ b/floof/model/comments.py
@@ -3,6 +3,47 @@ import datetime
 from elixir import *
 from sqlalchemy import func
 
+### Utility function(s)
+
+def indent_comments(comments):
+    """Given a list of comment objects, returns the same comments (and changes
+    them in-place) with an `indent` property set on each comment.  This
+    indicates how deeply nested each comment is, relative to the first comment.
+    The first comment's indent level is 0.
+
+    The comments must be a complete subtree, ordered by their `left` property.
+    """
+
+    last_comment = None
+    indent = 0 
+    right_ancestry = []
+    for comment in comments:
+        # If this comment is a child of the last, bump the nesting level
+        if last_comment and comment.left < last_comment.right:
+            indent = indent + 1 
+            # Remember current ancestory relevant to the root
+            right_ancestry.append(last_comment)
+
+        # On the other hand, for every nesting level this comment may have just
+        # broken out of, back out a level
+        for i in xrange(len(right_ancestry) - 1, -1, -1):
+            if comment.left > right_ancestry[i].right:
+                indent = indent - 1 
+                right_ancestry.pop(i)
+
+        # Cache parent comment
+        if len(right_ancestry):
+            comment._parent = right_ancestry[-1]
+
+        comment.indent = indent
+
+        last_comment = comment
+
+    return comments
+
+
+### Usual database classes
+
 class Discussion(Entity):
     """Represents a collection of comments attached to some other object."""
     count = Field(Integer)
@@ -34,19 +75,20 @@ class Comment(Entity):
         self.discussion.count += 1
 
         if parent:
-            # Parent comment given.  Add this comment just before the parent's
-            # right side...
-            self.left = parent.right
-            self.right = parent.right + 1
-
-            # ...then adjust all rightward comments accordingly
+            # Parent comment given.
+            parent_right = parent.right
+            # Shift every left/right ahead by two to make room for the new
+            # comment's left/right
+            Comment.query.filter(Comment.discussion == self.discussion) \
+                         .filter(Comment.left >= parent_right) \
+                         .update({ Comment.left: Comment.left + 2 })
             Comment.query.filter(Comment.discussion == self.discussion) \
-                         .filter(Comment.right > parent.right) \
-                         .update({ Comment.left:  Comment.left + 2,
-                                   Comment.right: Comment.right + 2 })
+                         .filter(Comment.right >= parent_right) \
+                         .update({ Comment.right: Comment.right + 2 })
 
-            # And, finally, update the parent's right endpoint
-            parent.right += 2
+            # Then stick the new comment in the right place
+            self.left = parent_right
+            self.right = parent_right + 1
 
         else:
             query = session.query(func.max(Comment.right)) \
@@ -60,3 +102,4 @@ class Comment(Entity):
             else:
                 self.left = max_right + 1
                 self.right = max_right + 2
+