1 files changed, 87 insertions, 0 deletions
diff --git a/app/controllers/concerns/status_controller_concern.rb b/app/controllers/concerns/status_controller_concern.rb
new file mode 100644
index 000000000..62a7cf508
--- /dev/null
+++ b/app/controllers/concerns/status_controller_concern.rb
@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+module StatusControllerConcern
+  extend ActiveSupport::Concern
+
+  ANCESTORS_LIMIT         = 40
+  DESCENDANTS_LIMIT       = 60
+  DESCENDANTS_DEPTH_LIMIT = 20
+
+  def create_descendant_thread(starting_depth, statuses)
+    depth = starting_depth + statuses.size
+
+    if depth < DESCENDANTS_DEPTH_LIMIT
+      {
+        statuses: statuses,
+        starting_depth: starting_depth,
+      }
+    else
+      next_status = statuses.pop
+
+      {
+        statuses: statuses,
+        starting_depth: starting_depth,
+        next_status: next_status,
+      }
+    end
+  end
+
+  def set_ancestors
+    @ancestors     = @status.reply? ? cache_collection(@status.ancestors(ANCESTORS_LIMIT, current_account), Status) : []
+    @next_ancestor = @ancestors.size < ANCESTORS_LIMIT ? nil : @ancestors.shift
+  end
+
+  def set_descendants
+    @max_descendant_thread_id   = params[:max_descendant_thread_id]&.to_i
+    @since_descendant_thread_id = params[:since_descendant_thread_id]&.to_i
+
+    descendants = cache_collection(
+      @status.descendants(
+        DESCENDANTS_LIMIT,
+        current_account,
+        @max_descendant_thread_id,
+        @since_descendant_thread_id,
+        DESCENDANTS_DEPTH_LIMIT
+      ),
+      Status
+    )
+
+    @descendant_threads = []
+
+    if descendants.present?
+      statuses       = [descendants.first]
+      starting_depth = 0
+
+      descendants.drop(1).each_with_index do |descendant, index|
+        if descendants[index].id == descendant.in_reply_to_id
+          statuses << descendant
+        else
+          @descendant_threads << create_descendant_thread(starting_depth, statuses)
+
+          # The thread is broken, assume it's a reply to the root status
+          starting_depth = 0
+
+          # ... unless we can find its ancestor in one of the already-processed threads
+          @descendant_threads.reverse_each do |descendant_thread|
+            statuses = descendant_thread[:statuses]
+
+            index = statuses.find_index do |thread_status|
+              thread_status.id == descendant.in_reply_to_id
+            end
+
+            if index.present?
+              starting_depth = descendant_thread[:starting_depth] + index + 1
+              break
+            end
+          end
+
+          statuses = [descendant]
+        end
+      end
+
+      @descendant_threads << create_descendant_thread(starting_depth, statuses)
+    end
+
+    @max_descendant_thread_id = @descendant_threads.pop[:statuses].first.id if descendants.size >= DESCENDANTS_LIMIT
+  end
+end