module Spree
  class ShippingMethod < Spree::Base
    acts_as_paranoid
    include Spree::CalculatedAdjustments
    DISPLAY = [:both, :front_end, :back_end]

    # Used for #refresh_rates
    DISPLAY_ON_FRONT_END = 1
    DISPLAY_ON_BACK_END = 2

    default_scope { where(deleted_at: nil) }

    has_many :shipping_method_categories, dependent: :destroy
    has_many :shipping_categories, through: :shipping_method_categories
    has_many :shipping_rates, inverse_of: :shipping_method
    has_many :shipments, through: :shipping_rates

    has_many :shipping_method_zones, class_name: 'Spree::ShippingMethodZone',
                                     foreign_key: 'shipping_method_id'
    has_many :zones, through: :shipping_method_zones, class_name: 'Spree::Zone'

    belongs_to :tax_category, class_name: 'Spree::TaxCategory', optional: true

    validates :name, presence: true

    validate :at_least_one_shipping_category

    def include?(address)
      return false unless address
      zones.includes(:zone_members).any? do |zone|
        zone.include?(address)
      end
    end

    def build_tracking_url(tracking)
      return if tracking.blank? || tracking_url.blank?
      tracking_url.gsub(/:tracking/, ERB::Util.url_encode(tracking)) # :url_encode exists in 1.8.7 through 2.1.0
    end

    def self.calculators
      spree_calculators.send(model_name_without_spree_namespace).
        select { |c| c.to_s.constantize < Spree::ShippingCalculator }
    end

    def tax_category
      Spree::TaxCategory.unscoped { super }
    end

    def available_to_display?(display_filter)
      (frontend? && display_filter == DISPLAY_ON_FRONT_END) ||
        (backend? && display_filter == DISPLAY_ON_BACK_END)
    end

    private

    # Some shipping methods are only meant to be set via backend
    def frontend?
      display_on.in?(['both', 'front_end'])
    end

    def backend?
      display_on.in?(['both', 'back_end'])
    end

    def at_least_one_shipping_category
      if shipping_categories.empty?
        errors.add(:base, :required_shipping_category)
      end
    end
  end
end
