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

3 files changed, 114 insertions, 2 deletions

diff --git a/app/services/activitypub/fetch_featured_collection_service.rb b/app/services/activitypub/fetch_featured_collection_service.rb
index 37d05e055..026fe24c5 100644
--- a/app/services/activitypub/fetch_featured_collection_service.rb
+++ b/app/services/activitypub/fetch_featured_collection_service.rb
@@ -3,10 +3,11 @@
 class ActivityPub::FetchFeaturedCollectionService < BaseService
   include JsonLdHelper
 
-  def call(account)
+  def call(account, **options)
     return if account.featured_collection_url.blank? || account.suspended? || account.local?
 
     @account = account
+    @options = options
     @json    = fetch_resource(@account.featured_collection_url, true, local_follower)
 
     return unless supported_context?(@json)
@@ -36,7 +37,15 @@ class ActivityPub::FetchFeaturedCollectionService < BaseService
   end
 
   def process_items(items)
+    process_note_items(items) if @options[:note]
+    process_hashtag_items(items) if @options[:hashtag]
+  end
+
+  def process_note_items(items)
     status_ids = items.filter_map do |item|
+      type = item['type']
+      next unless type == 'Note'
+
       uri = value_or_id(item)
       next if ActivityPub::TagManager.instance.local_uri?(uri)
 
@@ -67,6 +76,26 @@ class ActivityPub::FetchFeaturedCollectionService < BaseService
     end
   end
 
+  def process_hashtag_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)
 
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
diff --git a/app/services/activitypub/process_account_service.rb b/app/services/activitypub/process_account_service.rb
index 456b3524b..3834d79cc 100644
--- a/app/services/activitypub/process_account_service.rb
+++ b/app/services/activitypub/process_account_service.rb
@@ -39,6 +39,7 @@ class ActivityPub::ProcessAccountService < BaseService
 
     unless @options[:only_key] || @account.suspended?
       check_featured_collection! if @account.featured_collection_url.present?
+      check_featured_tags_collection! if @json['featuredTags'].present?
       check_links! unless @account.fields.empty?
     end
 
@@ -149,7 +150,11 @@ class ActivityPub::ProcessAccountService < BaseService
   end
 
   def check_featured_collection!
-    ActivityPub::SynchronizeFeaturedCollectionWorker.perform_async(@account.id)
+    ActivityPub::SynchronizeFeaturedCollectionWorker.perform_async(@account.id, { 'hashtag' => @json['featuredTags'].blank? })
+  end
+
+  def check_featured_tags_collection!
+    ActivityPub::SynchronizeFeaturedTagsCollectionWorker.perform_async(@account.id, @json['featuredTags'])
   end
 
   def check_links!