1 files changed, 85 insertions, 0 deletions
diff --git a/app/finders/autocomplete/users_finder.rb b/app/finders/autocomplete/users_finder.rb
new file mode 100644
index 00000000000..b2557469079
--- /dev/null
+++ b/app/finders/autocomplete/users_finder.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+
+module Autocomplete
+  class UsersFinder
+    # The number of users to display in the results is hardcoded to 20, and
+    # pagination is not supported. This ensures that performance remains
+    # consistent and removes the need for implementing keyset pagination to
+    # ensure good performance.
+    LIMIT = 20
+
+    attr_reader :current_user, :project, :group, :search, :skip_users,
+                :author_id, :todo_filter, :todo_state_filter,
+                :filter_by_current_user
+
+    def initialize(params:, current_user:, project:, group:)
+      @current_user = current_user
+      @project = project
+      @group = group
+      @search = params[:search]
+      @skip_users = params[:skip_users]
+      @author_id = params[:author_id]
+      @todo_filter = params[:todo_filter]
+      @todo_state_filter = params[:todo_state_filter]
+      @filter_by_current_user = params[:current_user]
+    end
+
+    def execute
+      items = limited_users
+
+      if search.blank?
+        # Include current user if available to filter by "Me"
+        items.unshift(current_user) if prepend_current_user?
+
+        if prepend_author? && (author = User.find_by_id(author_id))
+          items.unshift(author)
+        end
+      end
+
+      items.uniq
+    end
+
+    private
+
+    # Returns the users based on the input parameters, as an Array.
+    #
+    # This method is separate so it is easier to extend in EE.
+    def limited_users
+      # When changing the order of these method calls, make sure that
+      # reorder_by_name() is called _before_ optionally_search(), otherwise
+      # reorder_by_name will break the ORDER BY applied in optionally_search().
+      find_users
+        .active
+        .reorder_by_name
+        .optionally_search(search)
+        .where_not_in(skip_users)
+        .limit_to_todo_authors(
+          user: current_user,
+          with_todos: todo_filter,
+          todo_state: todo_state_filter
+        )
+        .limit(LIMIT)
+        .to_a
+    end
+
+    def prepend_current_user?
+      filter_by_current_user.present? && current_user
+    end
+
+    def prepend_author?
+      author_id.present? && current_user
+    end
+
+    def find_users
+      if project
+        project.authorized_users.union_with_user(author_id)
+      elsif group
+        group.users_with_parents
+      elsif current_user
+        User.all
+      else
+        User.none
+      end
+    end
+  end
+end