Update iteration cadence mutation [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Adds GraphQL support for updating iteration cadences. #322742 (closed)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

ee/app/finders/iterations/cadences_finder.rb

+# frozen_string_literal: true
+
+# Search for iterations cadences
+#
+# params - Hash
+#   id: Find iterations cadence by its ID.
+#   include_ancestor_groups: A flag to indicate if we should also look up iteration cadences in ancestor groups.
+#   title - Filter by title with a fuzzy match.
+
+module Iterations
+  class CadencesFinder
+    attr_reader :current_user, :group, :params
+
+    ResourceNotFoundError = Class.new(RuntimeError)
+
+    def initialize(current_user, group, params = {})
+      @current_user = current_user
+      @group = group
+      @params = params
+    end
+
+    def execute
+      raise ResourceNotFoundError, "Resource not found" unless group.iteration_cadences_enabled?
+
+      items = Iterations::Cadence.all
+      items = by_id(items)
+      items = by_groups(items)
+      items = by_title(items)
+      items = by_duration(items)
+      items = by_automatic(items)
+      items = by_active(items)
+
+      items.order(:title) # rubocop: disable CodeReuse/ActiveRecord
+    end
+
+    private
+
+    def by_groups(items)
+      items.with_groups(groups)
+    end
+
+    def groups
+      groups = groups_to_include(group)
+
+      # Because we are sure that all groups are in the same hierarchy tree
+      # we can preset root group for all of them to optimize permission checks
+      Group.preset_root_ancestor_for(groups)
+
+      groups_user_can_read_cadences(groups).map(&:id)
+    end
+
+    def groups_to_include(group)
+      groups = [group]
+      groups += group.ancestors if include_ancestor_groups?
+
+      groups
+    end
+
+    def groups_user_can_read_cadences(groups)
+      DeclarativePolicy.user_scope do
+        groups.select { |group| Ability.allowed?(current_user, :read_label, group) }
+      end
+    end
+
+    def include_ancestor_groups?
+      params[:include_ancestor_groups]
+    end
+
+    def by_id(items)
+      if params[:id]
+        items.id_in(params[:id])
+      else
+        items
+      end
+    end
+
+    def by_title(items)
+      if params[:title]
+        items.search_title(params[:title])
+      else
+        items
+      end
+    end
+
+    def by_duration(items)
+      return items if params[:duration_in_weeks].blank?
+
+      items.with_duration(params[:duration_in_weeks])
+    end
+
+    def by_automatic(items)
+      return items if params[:automatic].nil?
+
+      items.is_automatic(params[:automatic])
+    end
+
+    def by_active(items)
+      return items if params[:active].nil?
+
+      items.is_active(params[:active])
+    end
+  end
+end