Move Project#rename_repo to a service classrefactor-project-rename-repo

This moves the logic of Project#rename_repo and all methods _only_ used
by this method into a new service class: Projects::AfterRenameService.
By moving this code into a separate service class we can more easily
refactor it, and we also get rid of some RuboCop "disable" statements
automatically.

During the refactoring of this code, I removed most of the explicit
logging using Gitlab::AppLogger. The data that was logged would not be
useful when debugging renaming issues, as it does not add any value on
top of data provided by users.

I also removed a variety of comments that either mentioned something the
code does in literal form, or contained various grammatical errors.
Instead we now resort to more clearly named methods, removing the need
for code comments.

This method was chosen based on analysis in
https://gitlab.com/gitlab-org/release/framework/issues/28. In this issue
we determined this method has seen a total of 293 lines being changed in
it. We also noticed that RuboCop determined the ABC size
(https://www.softwarerenovation.com/ABCMetric.pdf) was too great.

3 files changed, 142 insertions, 74 deletions

diff --git a/app/models/project.rb b/app/models/project.rb
index b80e41e4a96..731272b3bf8 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -1640,34 +1640,6 @@ class Project < ActiveRecord::Base
   end
   # rubocop: enable CodeReuse/ServiceClass
 
-  def rename_repo
-    path_before      = previous_changes['path'].first
-    full_path_before = full_path_was
-    full_path_after  = build_full_path
-
-    Gitlab::AppLogger.info("Attempting to rename #{full_path_was} -> #{full_path_after}")
-
-    if has_container_registry_tags?
-      Gitlab::AppLogger.info("Project #{full_path_was} cannot be renamed because container registry tags are present!")
-
-      # we currently don't support renaming repository if it contains images in container registry
-      raise StandardError.new('Project cannot be renamed, because images are present in its container registry')
-    end
-
-    expire_caches_before_rename(full_path_before)
-
-    if rename_or_migrate_repository!
-      Gitlab::AppLogger.info("Project was renamed: #{full_path_before} -> #{full_path_after}")
-      after_rename_repository(full_path_before, path_before)
-    else
-      Gitlab::AppLogger.info("Repository could not be renamed: #{full_path_before} -> #{full_path_after}")
-
-      # if we cannot move namespace directory we should rollback
-      # db changes in order to prevent out of sync between db and fs
-      raise StandardError.new('Repository cannot be renamed')
-    end
-  end
-
   def write_repository_config(gl_full_path: full_path)
     # We'd need to keep track of project full path otherwise directory tree
     # created with hashed storage enabled cannot be usefully imported using
@@ -2096,51 +2068,6 @@ class Project < ActiveRecord::Base
     auto_cancel_pending_pipelines == 'enabled'
   end
 
-  private
-
-  # rubocop: disable CodeReuse/ServiceClass
-  def rename_or_migrate_repository!
-    if Gitlab::CurrentSettings.hashed_storage_enabled? &&
-        storage_upgradable? &&
-        Feature.disabled?(:skip_hashed_storage_upgrade) # kill switch in case we need to disable upgrade behavior
-      ::Projects::HashedStorageMigrationService.new(self, full_path_was).execute
-    else
-      storage.rename_repo
-    end
-  end
-  # rubocop: enable CodeReuse/ServiceClass
-
-  def storage_upgradable?
-    storage_version != LATEST_STORAGE_VERSION
-  end
-
-  def after_rename_repository(full_path_before, path_before)
-    execute_rename_repository_hooks!(full_path_before)
-
-    write_repository_config
-
-    # We need to check if project had been rolled out to move resource to hashed storage or not and decide
-    # if we need execute any take action or no-op.
-    unless hashed_storage?(:attachments)
-      Gitlab::UploadsTransfer.new.rename_project(path_before, self.path, namespace.full_path)
-    end
-
-    Gitlab::PagesTransfer.new.rename_project(path_before, self.path, namespace.full_path)
-  end
-
-  # rubocop: disable CodeReuse/ServiceClass
-  def execute_rename_repository_hooks!(full_path_before)
-    # When we import a project overwriting the original project, there
-    # is a move operation. In that case we don't want to send the instructions.
-    send_move_instructions(full_path_before) unless import_started?
-
-    self.old_path_with_namespace = full_path_before
-    SystemHooksService.new.execute_hooks_for(self, :rename)
-
-    reload_repository!
-  end
-  # rubocop: enable CodeReuse/ServiceClass
-
   def storage
     @storage ||=
       if hashed_storage?(:repository)
@@ -2150,6 +2077,12 @@ class Project < ActiveRecord::Base
       end
   end
 
+  def storage_upgradable?
+    storage_version != LATEST_STORAGE_VERSION
+  end
+
+  private
+
   def use_hashed_storage
     if self.new_record? && Gitlab::CurrentSettings.hashed_storage_enabled
       self.storage_version = LATEST_STORAGE_VERSION
diff --git a/app/services/projects/after_rename_service.rb b/app/services/projects/after_rename_service.rb
new file mode 100644
index 00000000000..4131da44f5a
--- /dev/null
+++ b/app/services/projects/after_rename_service.rb
@@ -0,0 +1,135 @@
+# frozen_string_literal: true
+
+module Projects
+  # Service class for performing operations that should take place after a
+  # project has been renamed.
+  #
+  # Example usage:
+  #
+  #     project = Project.find(42)
+  #
+  #     project.update(...)
+  #
+  #     Projects::AfterRenameService.new(project).execute
+  class AfterRenameService
+    attr_reader :project, :full_path_before, :full_path_after, :path_before
+
+    RenameFailedError = Class.new(StandardError)
+
+    # @param [Project] project The Project of the repository to rename.
+    def initialize(project)
+      @project = project
+
+      # The full path of the namespace + project, before the rename took place.
+      @full_path_before = project.full_path_was
+
+      # The full path of the namespace + project, after the rename took place.
+      @full_path_after = project.build_full_path
+
+      # The path of just the project, before the rename took place.
+      @path_before = project.path_was
+    end
+
+    def execute
+      first_ensure_no_registry_tags_are_present
+      expire_caches_before_rename
+      rename_or_migrate_repository!
+      send_move_instructions
+      execute_system_hooks
+      update_repository_configuration
+      rename_transferred_documents
+      log_completion
+    end
+
+    def first_ensure_no_registry_tags_are_present
+      return unless project.has_container_registry_tags?
+
+      raise RenameFailedError.new(
+        "Project #{full_path_before} cannot be renamed because images are " \
+          "present in its container registry"
+      )
+    end
+
+    def expire_caches_before_rename
+      project.expire_caches_before_rename(full_path_before)
+    end
+
+    def rename_or_migrate_repository!
+      success =
+        if migrate_to_hashed_storage?
+          ::Projects::HashedStorageMigrationService
+            .new(project, full_path_before)
+            .execute
+        else
+          project.storage.rename_repo
+        end
+
+      rename_failed! unless success
+    end
+
+    def send_move_instructions
+      return unless send_move_instructions?
+
+      project.send_move_instructions(full_path_before)
+    end
+
+    def execute_system_hooks
+      project.old_path_with_namespace = full_path_before
+      SystemHooksService.new.execute_hooks_for(project, :rename)
+    end
+
+    def update_repository_configuration
+      project.reload_repository!
+      project.write_repository_config
+    end
+
+    def rename_transferred_documents
+      if rename_uploads?
+        Gitlab::UploadsTransfer
+          .new
+          .rename_project(path_before, project_path, namespace_full_path)
+      end
+
+      Gitlab::PagesTransfer
+        .new
+        .rename_project(path_before, project_path, namespace_full_path)
+    end
+
+    def log_completion
+      Gitlab::AppLogger.info(
+        "Project #{project.id} has been renamed from " \
+          "#{full_path_before} to #{full_path_after}"
+      )
+    end
+
+    def migrate_to_hashed_storage?
+      Gitlab::CurrentSettings.hashed_storage_enabled? &&
+        project.storage_upgradable? &&
+        Feature.disabled?(:skip_hashed_storage_upgrade)
+    end
+
+    def send_move_instructions?
+      !project.import_started?
+    end
+
+    def rename_uploads?
+      !project.hashed_storage?(:attachments)
+    end
+
+    def project_path
+      project.path
+    end
+
+    def namespace_full_path
+      project.namespace.full_path
+    end
+
+    def rename_failed!
+      error = "Repository #{full_path_before} could not be renamed to #{full_path_after}"
+
+      Gitlab::AppLogger.error(error)
+
+      raise RenameFailedError.new(error)
+    end
+  end
+end
diff --git a/app/services/projects/update_service.rb b/app/services/projects/update_service.rb
index f25a4e30938..93e48fc0199 100644
--- a/app/services/projects/update_service.rb
+++ b/app/services/projects/update_service.rb
@@ -67,7 +67,7 @@ module Projects
       end
 
       if project.previous_changes.include?('path')
-        project.rename_repo
+        AfterRenameService.new(project).execute
       else
         system_hook_service.execute_hooks_for(project, :update)
       end