module Comee
  module Core
    class CustomerOrderService
      ##
      # This method converts a price value per a unit of measure to a price value per another
      # unit of measure.
      #
      # @param price [Numeric] the price value
      # @param unit [Numeric] the unit id of measure for the price
      # @param new_unit [Numeric] the new unit id of measure
      #
      # @return [Numeric] the converted price for the new unit
      #
      def convert_price(price, unit_id, new_unit_id)
        return price if unit_id == new_unit_id

        conversions = UnitConversion.where("from_id = ? AND to_id = ?", unit_id, new_unit_id)
                                    .or(UnitConversion.where("from_id = ? AND to_id = ?", new_unit_id, unit_id))
        unless conversions.count.positive?
          units = Unit.where(id: [unit_id, new_unit_id]).select(:code)
          raise(StandardError, "There is no conversion factor between #{units[0].code} and #{units[1].code}.")
        end

        conversion = conversions.first
        return (price / conversion.factor).round(2) if unit_id == conversion.from_id && new_unit_id == conversion.to_id

        (price * conversion.factor).round(2)
      end

      ##
      # This method converts a price value per a unit of measure to a price value per another
      # unit of measure.
      #
      # @param quantity [Numeric] the price value
      # @param unit_id [Numeric] the unit id of measure for the price
      # @param new_unit_id [Numeric] the new unit id of measure
      #
      # @return [Numeric] the converted price for the new unit
      #
      def convert_quantity(quantity, unit_id, new_unit_id)
        return quantity if unit_id == new_unit_id

        conversions = UnitConversion.where("from_id = ? AND to_id = ?", unit_id, new_unit_id)
                                    .or(UnitConversion.where("from_id = ? AND to_id = ?", new_unit_id, unit_id))

        unless conversions.count.positive?
          units = Unit.where(id: [unit_id, new_unit_id])
          raise(StandardError, "There is no conversion factor between #{units[0].code} and #{units[1].code}.")
        end

        conversion = conversions.first
        return (quantity * conversion.factor).round if unit_id == conversion.from_id && new_unit_id == conversion.to_id

        (quantity / conversion.factor).round
      end

      def suggest_values(item_id, new_unit_id)
        item = CustomerOrderItem.includes(:customer_order).find_by(id: item_id)
        raise(StandardError, "Order item with id `#{item_id}` not found.") unless item

        quantity = convert_quantity(item.quantity, item.unit_id, new_unit_id)
        client_price = ClientPrice.find_by(product_id: item.product_id, client_id: item.customer_order.client_id)
        if client_price
          price = convert_price(client_price.price, client_price.unit_id, new_unit_id)
        else
          master_price = MasterPrice.find_by(product_id: item.product_id, primary: true)
          raise(StandardError, "No price entry could be found for product `#{item.product.code}`.") unless master_price

          price = convert_price(master_price.selling_price, master_price.unit_id, new_unit_id)
        end
        {quantity: quantity, price: price}
      end

      def submit(id)
        order = CustomerOrder.find_by(id: id)
        raise(StandardError, "Customer order with id `#{id}` not found.") unless order

        unless CustomerOrder.statuses[order.status] == CustomerOrder.statuses[:draft]
          raise(StandardError, "Customer order should be in draft state.")
        end

        raise(StandardError, "Customer order should have at least one item.") unless order.customer_order_items.count.positive?

        order.update!(status: CustomerOrder.statuses[:submitted])
        order
      end

      def submit_for_confirmation(id)
        order = CustomerOrder.find_by(id: id)
        raise(StandardError, "Customer order with id `#{id}` not found.") unless order

        unless CustomerOrder.statuses[order.status] == CustomerOrder.statuses[:submitted]
          raise(StandardError, "Customer order should be in submitted state.")
        end

        raise(StandardError, "Customer order does not have any items.") if order.customer_order_items.count.zero?

        order.update!(status: CustomerOrder.statuses[:awaiting_confirmation])
        order
      end

      def accept(id)
        order = CustomerOrder.find_by(id: id)
        raise(StandardError, "Customer order with id `#{id}` not found.") unless order

        if CustomerOrder.statuses[order.status] == CustomerOrder.statuses[:accepted]
          raise(StandardError, "Customer order is already in accepted state.")
        end

        allowed_statuses = [CustomerOrder.statuses[:submitted], CustomerOrder.statuses[:awaiting_confirmation]]
        unless allowed_statuses.include?(CustomerOrder.statuses[order.status])
          raise(StandardError, "Customer order should be in submitted or awaiting confirmation state.")
        end

        if order.customer_order_items.count.zero? ||
           order.customer_order_items.all?(&:canceled?)
          raise(StandardError, "Customer order does not have any items.")
        end

        sales_order = nil
        CustomerOrder.transaction do
          sales_order = SalesOrder.create!(
            order_number: order.order_number,
            customer_order: order,
            status: SalesOrder.statuses[:draft]
          )
          order_items = order.customer_order_items.includes(:product, :unit)
          client_prices = ClientPrice.where(client: order.client, product_id: order_items.map(&:product_id))
          master_prices = MasterPrice.where(primary: true, status: Price.statuses[:current], product: order_items.map(&:product))
          items = order_items.each_with_object([]) do |item, res|
            next if item.canceled?

            default_unit = item.product.default_unit
            unit_id = default_unit ? default_unit["id"] : item.unit_id
            quantity = convert_quantity(item.quantity, item.unit_id, unit_id)
            client_price = client_prices.find { |price| price.product_id == item.product_id }
            master_price = master_prices.find { |price| price.product_id == item.product_id }
            if client_price
              price = convert_price(client_price.price, client_price.unit_id, unit_id)
            else
              raise(StandardError, "No price entry could be found for product `#{item.product.code}`.") unless master_price

              price = convert_price(master_price.selling_price, master_price.unit_id, unit_id)
            end

            res << {
              sales_order_id: sales_order.id,
              customer_order_item_id: item.id,
              product_id: item.product_id,
              unit_id: unit_id,
              customer_item_no: item.product.code,
              quantity: quantity,
              price: price,
              delivery_date: item.delivery_date,
              lead_time: master_price&.lead_time
            }
          end
          SalesOrderItem.insert_all!(items)
          order.update!(status: CustomerOrder.statuses[:accepted])
        end
        sales_order
      end

      def cancel(id)
        order = CustomerOrder.find_by(id: id)
        raise(StandardError, "Customer order with id `#{id}` not found.") unless order

        if CustomerOrder.statuses[order.status] == CustomerOrder.statuses[:canceled]
          raise(StandardError, "Customer order is already canceled.")
        end

        order.update!(status: CustomerOrder.statuses[:canceled])
        order
      end
    end
  end
end