# EasyParcel live courier rates as a real Spree shipping cost.
#
# The storefront has always shown live EasyParcel quotes — 20 couriers for a
# Melaka address, with logos and durations. What was missing is that the chosen
# one never reached Spree, so the customer picked "City-Link RM6.79" and the
# order was charged whatever the flat-rate method said. The quote screen looked
# decorative because of that last missing step, and I removed it on that reading.
# This restores it by making the selection the thing Spree actually charges.
#
# The amount is read from order.private_metadata['easyparcel_amount'], written
# ONLY by the storefront's /api/shipping/select route, which re-fetches the live
# quotes server-side and confirms the chosen service_id really costs that. The
# browser can PATCH cart metadata directly, so an unverified amount here would
# let a customer set their own shipping to one sen.
#
# No quote chosen => nil => no shipping rate => no fulfillment => checkout cannot
# complete. That is deliberate: a Malaysian order must carry a real courier.
#
# The class is defined INSIDE to_prepare: at initializer load time Spree is not
# autoloaded yet, and `require 'spree/shipping_calculator'` raises LoadError
# under Zeitwerk — that took the container down once.
#
# Bind-mounted — the prebuilt image mounts no app code. See docker-compose.yml.

Rails.application.config.to_prepare do
  unless defined?(Spree::Calculator::Shipping::EasyParcelQuote)
    Spree::Calculator::Shipping.const_set(
      :EasyParcelQuote,
      Class.new(Spree::ShippingCalculator) do
        preference :currency, :string, default: 'MYR'

        def self.description
          'EasyParcel live courier quote'
        end

        def compute_package(package)
          order = package.respond_to?(:order) ? package.order : nil
          return nil if order.nil?

          meta = order.private_metadata || {}
          raw = meta['easyparcel_amount'] || meta[:easyparcel_amount]
          return nil if raw.blank?

          BigDecimal(raw.to_s)
        rescue ArgumentError, TypeError
          # A malformed amount must not become a free shipment.
          nil
        end
      end
    )
  end

  # Registering only populates the admin's calculator dropdown; the method below
  # gets the class assigned directly, so a nil list here must not abort boot.
  klass = Spree::Calculator::Shipping::EasyParcelQuote
  list = Rails.application.config.spree.calculators&.shipping_methods
  list << klass if list.respond_to?(:include?) && !list.include?(klass)
end