Add synchronization of remote featured tags (#19380)

* Add LIMIT of featured tag to instance API response

* Add featured_tags_collection_url to Account

* Add synchronization of remote featured tags

* Deliver update activity when updating featured tag

* Remove featured_tags_collection_url

* Revert "Add featured_tags_collection_url to Account"

This reverts commit cff349fc27b104ded2df6bb5665132dc24dab09c.

* Add hashtag sync from featured collections

* Fix tag name normalize

* Add target option to fetch featured collection

* Refactor fetch_featured_tags_collection_service

* Add LIMIT of featured tag to v1/instance API response

1 files changed, 78 insertions, 0 deletions

diff --git a/app/services/activitypub/fetch_featured_tags_collection_service.rb b/app/services/activitypub/fetch_featured_tags_collection_service.rb
new file mode 100644
index 000000000..555919938
--- /dev/null
+++ b/app/services/activitypub/fetch_featured_tags_collection_service.rb
@@ -0,0 +1,78 @@
+# frozen_string_literal: true
+
+class ActivityPub::FetchFeaturedTagsCollectionService < BaseService
+  include JsonLdHelper
+
+  def call(account, url)
+    return if url.blank? || account.suspended? || account.local?
+
+    @account = account
+    @json    = fetch_resource(url, true, local_follower)
+
+    return unless supported_context?(@json)
+
+    process_items(collection_items(@json))
+  end
+
+  private
+
+  def collection_items(collection)
+    all_items = []
+
+    collection = fetch_collection(collection['first']) if collection['first'].present?
+
+    while collection.is_a?(Hash)
+      items = begin
+        case collection['type']
+        when 'Collection', 'CollectionPage'
+          collection['items']
+        when 'OrderedCollection', 'OrderedCollectionPage'
+          collection['orderedItems']
+        end
+      end
+
+      break if items.blank?
+
+      all_items.concat(items)
+
+      break if all_items.size >= FeaturedTag::LIMIT
+
+      collection = collection['next'].present? ? fetch_collection(collection['next']) : nil
+    end
+
+    all_items
+  end
+
+  def fetch_collection(collection_or_uri)
+    return collection_or_uri if collection_or_uri.is_a?(Hash)
+    return if invalid_origin?(collection_or_uri)
+
+    fetch_resource_without_id_validation(collection_or_uri, local_follower, true)
+  end
+
+  def process_items(items)
+    names     = items.filter_map { |item| item['type'] == 'Hashtag' && item['name']&.delete_prefix('#') }.map { |name| HashtagNormalizer.new.normalize(name) }
+    to_remove = []
+    to_add    = names
+
+    FeaturedTag.where(account: @account).map(&:name).each do |name|
+      if names.include?(name)
+        to_add.delete(name)
+      else
+        to_remove << name
+      end
+    end
+
+    FeaturedTag.includes(:tag).where(account: @account, tags: { name: to_remove }).delete_all unless to_remove.empty?
+
+    to_add.each do |name|
+      FeaturedTag.create!(account: @account, name: name)
+    end
+  end
+
+  def local_follower
+    return @local_follower if defined?(@local_follower)
+
+    @local_follower = @account.followers.local.without_suspended.first
+  end
+end