Refactor AutocompleteControllerdefine-abstraction-levels

This refactors the AutocompleteController according to the guidelines
and boundaries discussed in
https://gitlab.com/gitlab-org/gitlab-ce/issues/49653. Specifically,
ActiveRecord logic is moved to different finders, which are then used in
the controller. View logic in turn is moved to presenters, instead of
directly using ActiveRecord's "to_json" method.

The finder MoveToProjectFinder is also adjusted according to the
abstraction guidelines and boundaries, resulting in a much more simple
finder.

By using finders (and other abstractions) more actively, we can push a
lot of logic out of the controller. We also remove the need for various
"before_action" hooks, though this could be achieved without using
finders as well.

The various finders related to AutcompleteController have also been
moved into a namespace. This removes the need for calling everything
"AutocompleteSmurfFinder", instead you can use
"Autocomplete::SmurfFinder".

1 files changed, 22 insertions, 50 deletions

diff --git a/app/controllers/autocomplete_controller.rb b/app/controllers/autocomplete_controller.rb
index 86bade49ec9..9e30b982b06 100644
--- a/app/controllers/autocomplete_controller.rb
+++ b/app/controllers/autocomplete_controller.rb
@@ -1,67 +1,39 @@
 class AutocompleteController < ApplicationController
-  AWARD_EMOJI_MAX = 100
-
   skip_before_action :authenticate_user!, only: [:users, :award_emojis]
-  before_action :load_project, only: [:users]
-  before_action :load_group, only: [:users]
 
   def users
-    @users = AutocompleteUsersFinder.new(params: params, current_user: current_user, project: @project, group: @group).execute
-
-    render json: UserSerializer.new.represent(@users)
-  end
-
-  def user
-    @user = User.find(params[:id])
-    render json: UserSerializer.new.represent(@user)
-  end
-
-  def projects
-    project = Project.find_by_id(params[:project_id])
-    projects = projects_finder.execute(project, search: params[:search], offset_id: params[:offset_id])
+    project = Autocomplete::ProjectFinder
+      .new(current_user, params)
+      .execute
 
-    render json: projects.to_json(only: [:id, :name_with_namespace], methods: :name_with_namespace)
-  end
+    group = Autocomplete::GroupFinder
+      .new(current_user, project, params)
+      .execute
 
-  def award_emojis
-    emoji_with_count = AwardEmoji
-      .limit(AWARD_EMOJI_MAX)
-      .where(user: current_user)
-      .group(:name)
-      .order('count_all DESC, name ASC')
-      .count
+    users = Autocomplete::UsersFinder
+      .new(params: params, current_user: current_user, project: project, group: group)
+      .execute
 
-    # Transform from hash to array to guarantee json order
-    # e.g. { 'thumbsup' => 2, 'thumbsdown' = 1 }
-    #   => [{ name: 'thumbsup' }, { name: 'thumbsdown' }]
-    render json: emoji_with_count.map { |k, v| { name: k } }
+    render json: UserSerializer.new.represent(users)
   end
 
-  private
-
-  def load_group
-    @group ||= begin
-      if @project.blank? && params[:group_id].present?
-        group = Group.find(params[:group_id])
-        return render_404 unless can?(current_user, :read_group, group)
+  def user
+    user = UserFinder.new(params).execute!
 
-        group
-      end
-    end
+    render json: UserSerializer.new.represent(user)
   end
 
-  def load_project
-    @project ||= begin
-      if params[:project_id].present?
-        project = Project.find(params[:project_id])
-        return render_404 unless can?(current_user, :read_project, project)
+  # Displays projects to use for the dropdown when moving a resource from one
+  # project to another.
+  def projects
+    projects = Autocomplete::MoveToProjectFinder
+      .new(current_user, params)
+      .execute
 
-        project
-      end
-    end
+    render json: MoveToProjectSerializer.new.represent(projects)
   end
 
-  def projects_finder
-    MoveToProjectFinder.new(current_user)
+  def award_emojis
+    render json: AwardedEmojiFinder.new(current_user).execute
   end
 end