spree/spree-product-assembly

module Spree::OrderContentsDecorator
  def add_to_line_item(variant, quantity, options = {})
    line_item = grab_line_item_by_variant(variant, false, options)

    if line_item && part_variants_match?(line_item, variant, quantity, options)
      line_item.quantity += quantity.to_i
      line_item.currency = currency unless currency.nil?
    else
      opts = { currency: order.currency }.merge(whitelist(options))
      line_item = order.line_items.new(quantity: quantity,
                                        variant: variant,
                                        options: opts)
    end

    line_item.target_shipment = options[:shipment] if options.has_key? :shipment
    line_item.save!

    line_item
  end

  def add_to_line_item_with_parts(variant, quantity, options = {})
    add_to_line_item_without_parts(variant, quantity, options).
      tap do |line_item|
      populate_part_line_items(
        line_item,
        variant.parts_variants,
        options["selected_variants"]
      )
    end
  end

  alias_method :add_to_line_item_without_parts, :add_to_line_item
  alias_method :add_to_line_item, :add_to_line_item_with_parts

  private

  def part_variants_match?(line_item, variant, quantity, options)
    if line_item.parts.any? && options["selected_variants"]
      selected_variant_ids = options["selected_variants"].values.map(&:to_i)
      matched = part_variant_ids(line_item) & selected_variant_ids

      matched == selected_variant_ids
    else
      true
    end
  end

  def part_variant_ids(line_item)
    line_item.part_line_items.map(&:variant_id)
  end

  def populate_part_line_items(line_item, parts, selected_variants)
    parts.each do |part|
      part_line_item = line_item.part_line_items.find_or_initialize_by(
        line_item: line_item,
        variant_id: variant_id_for(part, selected_variants)
      )

      part_line_item.update!(quantity: part.count)
    end
  end

  def variant_id_for(part, selected_variants)
    if part.variant_selection_deferred?
      selected_variants[part.part.id.to_s]
    else
      part.part.id
    end
  end

  def whitelist(params)
    if params.is_a? ActionController::Parameters
      params.permit(Spree::PermittedAttributes.line_item_attributes)
    else
      params.slice(Spree::PermittedAttributes.line_item_attributes)
    end
  end
end

Spree::OrderContents.prepend Spree::OrderContentsDecorator if Spree.version.to_f < 3.7