Give the sitemap its own view, with collapse and descendant counts

Extracted from admin#index's inline table into NodesController#sitemap.
Nested <details>/<summary> per branch, one linear pass over the
existing flat [node, level] list (no added queries) -- each node's own
descendant count computed the same way, via a small stack rather than
re-walking the tree per node. Branches under updates/, club/erfas,
club/chaostreffs, and disclosure start collapsed by default
(CccConventions::SITEMAP_COLLAPSED_PATHS); any branch currently
collapsed, whether by that default or because someone just closed it,
is highlighted via a plain :not([open]) selector -- no state tracked
outside the DOM itself.

Dropped the update?-post exclusion this view used to rely on -- no
longer needed now that updates/ collapses instead of being filtered
out, so its real children (previously silently absent) now show up
correctly. admin#index's own, separate @sitemap query is unchanged;
that view has no collapse mechanism to compensate and wasn't part of
this.

1 files changed, 23 insertions, 0 deletions

diff --git a/app/controllers/nodes_controller.rb b/app/controllers/nodes_controller.rb
index ede91ad..772bf4b 100644
--- a/app/controllers/nodes_controller.rb
+++ b/app/controllers/nodes_controller.rb
@@ -216,6 +216,11 @@ class NodesController < ApplicationController
     @nodes = nodes_matching_tags(tags)
   end
 
+  def sitemap
+    @sitemap = Node.root.self_and_descendants_ordered_with_level
+    @sitemap_descendant_counts = descendant_counts_for(@sitemap)
+  end
+
   private
 
     def slug_for(title)
@@ -248,6 +253,24 @@ class NodesController < ApplicationController
       end
     end
 
+    def descendant_counts_for(ordered_with_level)
+      counts = Hash.new(0)
+      stack = [] # [node, level, index]
+      ordered_with_level.each_with_index do |(node, level), index|
+        while stack.any? && stack.last[1] >= level
+          ancestor_node, _ancestor_level, ancestor_index = stack.pop
+          counts[ancestor_node.id] = index - ancestor_index - 1
+        end
+        stack << [node, level, index]
+      end
+      total = ordered_with_level.length
+      while stack.any?
+        ancestor_node, _ancestor_level, ancestor_index = stack.pop
+        counts[ancestor_node.id] = total - ancestor_index - 1
+      end
+      counts
+    end
+
     def nodes_matching_tags(tags)
       matching_pages = Page.tagged_with(tags, any: true).reselect(:id)
       base = Node.where(head_id: matching_pages).or(Node.where(draft_id: matching_pages))