# frozen_string_literal: true

module Spree
  module Core
    module CalculatedAdjustments
      def self.included(klass)
        klass.class_eval do
          has_one :calculator, class_name: "Spree::Calculator", as: :calculable, dependent: :destroy
          accepts_nested_attributes_for :calculator
          validates :calculator, presence: true

          def self.calculators
            spree_calculators.__send__(model_name_without_spree_namespace)
          end

          def calculator_type
            calculator.class.to_s if calculator
          end

          def calculator_type=(calculator_type)
            klass = calculator_type.constantize if calculator_type
            self.calculator = klass.new if klass && !calculator.is_a?(klass)
          end

          # Creates a new adjustment for the target object
          #   (which is any class that has_many :adjustments) and sets amount based on the
          #   calculator as applied to the given calculable (Order, LineItems[], Shipment, etc.)
          # By default the adjustment will not be considered mandatory
          def create_adjustment(label, target, calculable, mandatory = false, state = "closed")
            # Adjustment calculations done on Spree::Shipment objects MUST
            # be done on their to_package'd variants instead
            # It's only the package that contains the correct information.
            # See https://github.com/spree/spree_active_shipping/pull/96 et. al
            old_calculable = calculable
            calculable = calculable.to_package if calculable.is_a?(Spree::Shipment)
            amount = compute_amount(calculable)
            return if amount.zero? && !mandatory

            target.adjustments.create(
              amount: amount,
              source: old_calculable,
              originator: self,
              label: label,
              mandatory: mandatory,
              state: state
            )
          end

          # Updates the amount of the adjustment using our Calculator and
          #   calling the +compute+ method with the +calculable+
          #   referenced passed to the method.
          def update_adjustment(adjustment, calculable)
            # Adjustment calculations done on Spree::Shipment objects MUST
            # be done on their to_package'd variants instead
            # It's only the package that contains the correct information.
            # See https://github.com/spree/spree_active_shipping/pull/96 et. al
            calculable = calculable.to_package if calculable.is_a?(Spree::Shipment)
            adjustment.update_column(:amount, compute_amount(calculable))
          end

          # Calculate the amount to be used when creating an adjustment
          # NOTE: May be overriden by classes where this module is included into.
          # Such as Spree::Promotion::Action::CreateAdjustment.
          def compute_amount(calculable)
            calculator.compute(calculable)
          end

          def self.model_name_without_spree_namespace
            to_s.tableize.gsub('/', '_').sub('spree_', '')
          end
          private_class_method :model_name_without_spree_namespace

          def self.spree_calculators
            Rails.application.config.spree.calculators
          end
          private_class_method :spree_calculators
        end
      end
    end
  end
end