module Billing
  class Account < ActiveRecord::Base
    monetize :charges_sum_cents
    monetize :discounts_sum_cents
    monetize :surcharges_sum_cents
    monetize :payments_sum_cents
    monetize :total_cents
    monetize :balance_cents
    
    belongs_to :billable, polymorphic: true
    has_many :charges, inverse_of: :account
    has_many :modifiers, inverse_of: :account
    has_many :payments, inverse_of: :account
    
    accepts_nested_attributes_for :charges, :modifiers, :payments
    
    before_validation :update_sumaries
    
    validates_numericality_of :total, greater_than_or_equal_to: 0
    
    def charge(*args)
      c = charges.new Charge.args(*args)
      c if c.save
    end
    
    def modify(*args)
      m = modifiers.new Modifier.args(*args)
      m if m.save
    end
    
    def pay(*args)
      p = payments.new Payment.args(*args)
      p if p.save
    end
    
    def modifier_items
      calculate_modifiers
    end
    
    def payment_types
      billable.try(:billing_payment_types) || billable.try(:payment_types) || []
    end

    private
      def calculate_modifiers
        @modifier_items = ModifierItems.new.tap() do |items|
          modifiers.each do |modifier|
            if charge = modifier.charge
              items << Charge.new(price: modifier.percent_ratio.nil? ? modifier.fixed_value : (charge.price * modifier.percent_ratio), chargable: charge)
            else
              items << Charge.new(price: modifier.percent_ratio.nil? ? modifier.fixed_value : (charges.to_a.sum(&:price).to_money * modifier.percent_ratio))
            end
          end
        end
      end
      def update_sumaries
        self.charges_sum = charges.to_a.sum(&:price).to_money
        calculate_modifiers
        self.discounts_sum = -@modifier_items.discounts.sum(&:price).to_money
        self.surcharges_sum = @modifier_items.surcharges.sum(&:price).to_money
        self.payments_sum = payments.to_a.sum(&:value).to_money
        self.total = charges_sum + surcharges_sum - discounts_sum
        self.balance = payments_sum - total
      end
  end
end