# frozen_string_literal: true

module CoreExtensions
  module ActiveRecord
    # Assumes that the model has the #position attribute and adds 2 features to a model that
    # includes it:
    # 1. Set the :position to the next highest value when a new row is added. If the model has a
    #    position_sorting_scope scope or class method, this is used to narrow the range of records
    #    searched when finding the current max position
    # 2. Add ability to sort rows based on an array of ids.
    #
    # TODO: move to a model concern and include selectively rather than globally.
    module Sort
      def self.included(base)
        base.extend ClassMethods

        base.before_create :set_position
      end

      module ClassMethods
        # A controller #sort action might for instance invoke this class method on an object.
        # The array of ids are the model to sort, and sorting is done by updating each model's
        # position to reflect their place in the array.
        def sort(ids)
          Array(ids).each_with_index do |id, index|
            where(id: id).update_all(["position=?", index + 1])
          end
        end
      end

      # Invoked by the callback when a record is created to set the initial value of #position.
      # If no position_sorting_scope is defined on the model class, we set position to the max
      # position in the whole table. If position_sorting_scope is provided we use it to refine the
      # grouping and hence the max(position) found - for example to get the max position where
      # patient_id = 123
      #
      # Example scope in a model:
      #   scope :position_sorting_scope, ->(problem) { where(patient_id: problem.patient.id) }
      #
      def set_position
        return unless respond_to?(:position)

        scope = if self.class.respond_to?(:position_sorting_scope)
                  self.class.position_sorting_scope(self)
                else
                  self.class
                end
        self.position = (scope.maximum(:position) || 0) + 1
      end
    end
  end
end