Give the `replies` collection an identifier and enable pagination (#10128)

1 files changed, 53 insertions, 0 deletions

diff --git a/app/controllers/statuses_controller.rb b/app/controllers/statuses_controller.rb
index 15d59fd89..3686bd9fd 100644
--- a/app/controllers/statuses_controller.rb
+++ b/app/controllers/statuses_controller.rb
@@ -18,6 +18,7 @@ class StatusesController < ApplicationController
   before_action :redirect_to_original, only: [:show]
   before_action :set_referrer_policy_header, only: [:show]
   before_action :set_cache_headers
+  before_action :set_replies, only: [:replies]
 
   content_security_policy only: :embed do |p|
     p.frame_ancestors(false)
@@ -63,8 +64,37 @@ class StatusesController < ApplicationController
     render 'stream_entries/embed', layout: 'embedded'
   end
 
+  def replies
+    skip_session!
+
+    render json: replies_collection_presenter,
+           serializer: ActivityPub::CollectionSerializer,
+           adapter: ActivityPub::Adapter,
+           content_type: 'application/activity+json',
+           skip_activities: true
+  end
+
   private
 
+  def replies_collection_presenter
+    page = ActivityPub::CollectionPresenter.new(
+      id: replies_account_status_url(@account, @status, page_params),
+      type: :unordered,
+      part_of: replies_account_status_url(@account, @status),
+      next: next_page,
+      items: @replies.map { |status| status.local ? status : status.id }
+    )
+    if page_requested?
+      page
+    else
+      ActivityPub::CollectionPresenter.new(
+        id: replies_account_status_url(@account, @status),
+        type: :unordered,
+        first: page
+      )
+    end
+  end
+
   def create_descendant_thread(starting_depth, statuses)
     depth = starting_depth + statuses.size
     if depth < DESCENDANTS_DEPTH_LIMIT
@@ -174,4 +204,27 @@ class StatusesController < ApplicationController
     return if @status.public_visibility? || @status.unlisted_visibility?
     response.headers['Referrer-Policy'] = 'origin'
   end
+
+  def page_requested?
+    params[:page] == 'true'
+  end
+
+  def set_replies
+    @replies = page_params[:other_accounts] ? Status.where.not(account_id: @account.id) : @account.statuses
+    @replies = @replies.where(in_reply_to_id: @status.id, visibility: [:public, :unlisted])
+    @replies = @replies.paginate_by_min_id(DESCENDANTS_LIMIT, params[:min_id])
+  end
+
+  def next_page
+    last_reply = @replies.last
+    return if last_reply.nil?
+    same_account = last_reply.account_id == @account.id
+    return unless same_account || @replies.size == DESCENDANTS_LIMIT
+    same_account = false unless @replies.size == DESCENDANTS_LIMIT
+    replies_account_status_url(@account, @status, page: true, min_id: last_reply.id, other_accounts: !same_account)
+  end
+
+  def page_params
+    { page: true, other_accounts: params[:other_accounts], min_id: params[:min_id] }.compact
+  end
 end