Use ResourceLabelEvent for tracking label changes

5 files changed, 212 insertions, 22 deletions

diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index 7f14d78e976..5f65fceb7af 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -109,10 +109,6 @@ module Issuable
       false
     end
 
-    def etag_caching_enabled?
-      false
-    end
-
     def has_multiple_assignees?
       assignees.count > 1
     end
diff --git a/app/models/concerns/noteable.rb b/app/models/concerns/noteable.rb
index ce778eae271..098eed137ba 100644
--- a/app/models/concerns/noteable.rb
+++ b/app/models/concerns/noteable.rb
@@ -82,4 +82,23 @@ module Noteable
   def lockable?
     [MergeRequest, Issue].include?(self.class)
   end
+
+  def etag_caching_enabled?
+    false
+  end
+
+  def expire_note_etag_cache
+    return unless discussions_rendered_on_frontend?
+    return unless etag_caching_enabled?
+
+    Gitlab::EtagCaching::Store.new.touch(note_etag_key)
+  end
+
+  def note_etag_key
+    Gitlab::Routing.url_helpers.project_noteable_notes_path(
+      project,
+      target_type: self.class.name.underscore,
+      target_id: id
+    )
+  end
 end
diff --git a/app/models/label_note.rb b/app/models/label_note.rb
new file mode 100644
index 00000000000..680952cf421
--- /dev/null
+++ b/app/models/label_note.rb
@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+class LabelNote < Note
+  attr_accessor :resource_parent
+  attr_reader :events
+
+  def self.from_events(events, resource: nil, resource_parent: nil)
+    resource ||= events.first.issuable
+
+    attrs = {
+      system: true,
+      author: events.first.user,
+      created_at: events.first.created_at,
+      discussion_id: events.first.discussion_id,
+      noteable: resource,
+      system_note_metadata: SystemNoteMetadata.new(action: 'label'),
+      events: events,
+      resource_parent: resource_parent
+    }
+
+    if resource_parent.is_a?(Project)
+      attrs[:project_id] = resource_parent.id
+    end
+
+    LabelNote.new(attrs)
+  end
+
+  def events=(events)
+    @events = events
+
+    update_outdated_markdown
+  end
+
+  def cached_html_up_to_date?(markdown_field)
+    true
+  end
+
+  def note
+    @note ||= note_text
+  end
+
+  def note_html
+    @note_html ||= "<p dir=\"auto\">#{note_text(html: true)}</p>"
+  end
+
+  def project
+    resource_parent if resource_parent.is_a?(Project)
+  end
+
+  def group
+    resource_parent if resource_parent.is_a?(Group)
+  end
+
+  private
+
+  def update_outdated_markdown
+    events.each do |event|
+      if event.outdated_markdown?
+        event.refresh_invalid_reference
+      end
+    end
+  end
+
+  def note_text(html: false)
+    added = labels_str('added', label_refs_by_action('add', html))
+    removed = labels_str('removed', label_refs_by_action('remove', html))
+
+    [added, removed].compact.join(' and ')
+  end
+
+  # returns string containing added/removed labels including
+  # count of deleted labels:
+  #
+  # added ~1 ~2 + 1 deleted label
+  # added 3 deleted labels
+  # added ~1 ~2 labels
+  def labels_str(prefix, label_refs)
+    existing_refs = label_refs.select { |ref| ref.present? }.sort
+    refs_str = existing_refs.empty? ? nil : existing_refs.join(' ')
+
+    deleted = label_refs.count - existing_refs.count
+    deleted_str = deleted == 0 ? nil : "#{deleted} deleted"
+
+    return nil unless refs_str || deleted_str
+
+    label_list_str = [refs_str, deleted_str].compact.join(' + ')
+    suffix = 'label'.pluralize(deleted > 0 ? deleted : existing_refs.count)
+
+    "#{prefix} #{label_list_str} #{suffix}"
+  end
+
+  def label_refs_by_action(action, html)
+    field = html ? :reference_html : :reference
+
+    events.select { |e| e.action == action }.map(&field)
+  end
+end
diff --git a/app/models/note.rb b/app/models/note.rb
index 2e343b8f9f8..8f090cc31e6 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -389,18 +389,7 @@ class Note < ActiveRecord::Base
   end
 
   def expire_etag_cache
-    return unless noteable&.discussions_rendered_on_frontend?
-    return unless noteable&.etag_caching_enabled?
-
-    Gitlab::EtagCaching::Store.new.touch(etag_key)
-  end
-
-  def etag_key
-    Gitlab::Routing.url_helpers.project_noteable_notes_path(
-      project,
-      target_type: noteable_type.underscore,
-      target_id: noteable_id
-    )
+    noteable&.expire_note_etag_cache
   end
 
   def touch(*args)
diff --git a/app/models/resource_label_event.rb b/app/models/resource_label_event.rb
index 42c255fcd1e..3fd96b9dc18 100644
--- a/app/models/resource_label_event.rb
+++ b/app/models/resource_label_event.rb
@@ -3,33 +3,122 @@
 # This model is not used yet, it will be used for:
 # https://gitlab.com/gitlab-org/gitlab-ce/issues/48483
 class ResourceLabelEvent < ActiveRecord::Base
+  include Importable
+  include Gitlab::Utils::StrongMemoize
+  include CacheMarkdownField
+
+  cache_markdown_field :reference
+
   belongs_to :user
   belongs_to :issue
   belongs_to :merge_request
   belongs_to :label
 
-  validates :user, presence: true, on: :create
-  validates :label, presence: true, on: :create
+  scope :created_after, ->(time) { where('created_at > ?', time) }
+
+  validates :user, presence: { unless: :importing? }, on: :create
+  validates :label, presence: { unless: :importing? }, on: :create
   validate :exactly_one_issuable
 
+  after_save :expire_etag_cache
+  after_destroy :expire_etag_cache
+
   enum action: {
     add: 1,
     remove: 2
   }
 
-  def self.issuable_columns
-    %i(issue_id merge_request_id).freeze
+  def self.issuable_attrs
+    %i(issue merge_request).freeze
   end
 
   def issuable
     issue || merge_request
   end
 
+  # create same discussion id for all actions with the same user and time
+  def discussion_id(resource = nil)
+    strong_memoize(:discussion_id) do
+      Digest::SHA1.hexdigest([self.class.name, created_at, user_id].join("-"))
+    end
+  end
+
+  def project
+    issuable.project
+  end
+
+  def group
+    issuable.group if issuable.respond_to?(:group)
+  end
+
+  def outdated_markdown?
+    return true if label_id.nil? && reference.present?
+
+    reference.nil? || latest_cached_markdown_version != cached_markdown_version
+  end
+
+  def banzai_render_context(field)
+    super.merge(pipeline: 'label', only_path: true)
+  end
+
+  def refresh_invalid_reference
+    # label_id could be nullified on label delete
+    self.reference = '' if label_id.nil?
+
+    # reference is not set for events which were not rendered yet
+    self.reference ||= label_reference
+
+    if changed?
+      save
+    elsif invalidated_markdown_cache?
+      refresh_markdown_cache!
+    end
+  end
+
   private
 
+  def label_reference
+    if local_label?
+      label.to_reference(format: :id)
+    elsif label.is_a?(GroupLabel)
+      label.to_reference(label.group, target_project: resource_parent, format: :id)
+    else
+      label.to_reference(resource_parent, format: :id)
+    end
+  end
+
   def exactly_one_issuable
-    if self.class.issuable_columns.count { |attr| self[attr] } != 1
-      errors.add(:base, "Exactly one of #{self.class.issuable_columns.join(', ')} is required")
+    issuable_count = self.class.issuable_attrs.count { |attr| self["#{attr}_id"] }
+
+    return true if issuable_count == 1
+
+    # if none of issuable IDs is set, check explicitly if nested issuable
+    # object is set, this is used during project import
+    if issuable_count == 0 && importing?
+      issuable_count = self.class.issuable_attrs.count { |attr| self.public_send(attr) } # rubocop:disable GitlabSecurity/PublicSend
+
+      return true if issuable_count == 1
     end
+
+    errors.add(:base, "Exactly one of #{self.class.issuable_attrs.join(', ')} is required")
+  end
+
+  def expire_etag_cache
+    issuable.expire_note_etag_cache
+  end
+
+  def local_label?
+    params = { include_ancestor_groups: true }
+    if resource_parent.is_a?(Project)
+      params[:project_id] = resource_parent.id
+    else
+      params[:group_id] = resource_parent.id
+    end
+
+    LabelsFinder.new(nil, params).execute(skip_authorization: true).where(id: label.id).any?
+  end
+
+  def resource_parent
+    issuable.project || issuable.group
   end
 end