Migrate shipping taxes to adjustments

db/migrate/20210224190247_migrate_shipping_taxes.rb

@@ -0,0 +1,83 @@
+class MigrateShippingTaxes < ActiveRecord::Migration
+  def up
+    return unless instance_uses_shipping_tax?
+
+    create_shipping_tax_rates
+    assign_to_shipping_methods
+    migrate_tax_amounts_to_adjustments
+  end
+
+  def instance_uses_shipping_tax?
+    Spree::Preference.find_by(key: '/spree/app_configuration/shipment_inc_vat').value
+  end
+
+  def instance_shipping_tax_rate
+    Spree::Preference.find_by(key: '/spree/app_configuration/shipping_tax_rate').value
+  end
+  
+  def shipping_tax_category
+    @shipping_tax_category ||= Spree::TaxCategory.create(name: I18n.t(:shipping))
+  end
+  
+  def create_shipping_tax_rates
+    # Create a shipping tax rate for each zone, set to current default rate
+    Spree::Zone.all.each do |tax_zone|
+      Spree::TaxRate.create!(
+        name: shipping_rate_label(tax_zone),
+        zone: tax_zone,
+        tax_category: shipping_tax_category,
+        amount: instance_shipping_tax_rate,
+        included_in_price: true,
+        calculator: Calculator::DefaultTax.new
+      )
+    end
+  end
+
+  def assign_to_shipping_methods
+    # Assign the new default shipping tax category to all existing shipping methods
+    Spree::ShippingMethod.update_all(tax_category_id: shipping_tax_category.id)
+  end
+  
+  def migrate_tax_amounts_to_adjustments
+    # Migrate all shipping tax amounts from shipment field to tax adjustments
+    Spree::Adjustment.shipping.where("included_tax <> 0").includes(:source, :order).find_each do |shipping_fee|
+      shipment = shipping_fee.source
+      order = shipping_fee.order
+      next if order.nil?
+
+      tax_rate = Spree::TaxRate.find_by(tax_category: shipping_tax_category, zone: order.tax_zone)
+
+      # Move all tax totals to adjustments
+      Spree::Adjustment.create!(
+        label: tax_adjustment_label(tax_rate),
+        amount: shipping_fee.included_tax,
+        included: true,
+        order_id: order.id,
+        state: "closed",
+        adjustable_type: "Spree::Shipment",
+        adjustable_id: shipment.id,
+        source_type: "Spree::Shipment",
+        source_id: shipment.id,
+        originator_type: "Spree::TaxRate",
+        originator_id: tax_rate.id
+      )
+
+      # Update shipment included tax total
+      shipment.update_columns(
+        included_tax_total: shipping_fee.included_tax
+      )
+    end
+  end
+
+  def shipping_rate_label(zone)
+    I18n.t(:shipping) + " - #{zone.name.chomp('_VAT')}"
+  end
+
+  def tax_adjustment_label(tax_rate)
+    label = ""
+    label << tax_rate.name
+    label << " #{tax_rate.amount * 100}%"
+    label << " (#{I18n.t('models.tax_rate.included_in_price')})"
+    label
+  end
+end