module Voucherify
  module Utils
    def self.round_money(value)
      value.round(2)
    end

    def self.validate_percent_discount(discount)
      if !(discount.is_a? Numeric) || !discount.between?(0, 100)
        raise 'Invalid voucher, percent discount should be between 0-100.'
      end
    end

    def self.validate_amount_discount(discount)
      if !(discount.is_a? Numeric) || discount < 0
        raise 'Invalid voucher, amount discount must be bigger than zero.'
      end
    end

    def self.validate_unit_discount(discount)
      if !(discount.is_a? Numeric) || discount < 0
        raise 'Invalid voucher, unit discount must be bigger than zero.'
      end
    end

    def self.calculate_price(base_price, voucher, unit_price = nil)
      e = 100.0

      if voucher[:gift]
        discount = [voucher[:gift][:balance] / e, base_price].min
        return round_money(base_price - discount)
      end

      if !voucher[:discount]
        raise 'Unsupported voucher type.'
      end

      if voucher[:discount][:type] === 'PERCENT'
        discount = voucher[:discount][:percent_off]
        validate_percent_discount(discount);
        price_discount = base_price * (discount / 100.0)
        return round_money(base_price - price_discount)

      elsif voucher[:discount][:type] === 'AMOUNT'
        discount = voucher[:discount][:amount_off] / e
        validate_amount_discount(discount)
        new_price = base_price - discount
        return round_money(new_price > 0 ? (new_price) : 0)

      elsif voucher[:discount][:type] === 'UNIT'
        if !unit_price
          raise 'Missing unit_price argument.'
        end
        discount = voucher[:discount][:unit_off]
        validate_unit_discount(discount)
        new_price = base_price - unit_price * discount
        return round_money(new_price > 0 ? (new_price) : 0)

      else
        raise 'Unsupported discount type'
      end
    end

    def self.calculate_discount(base_price, voucher, unit_price = nil)
      e = 100.0

      if voucher[:gift]
        discount = [voucher[:gift][:balance] / e, base_price].min
        return round_money(discount)
      end

      if !voucher[:discount]
        raise 'Unsupported voucher type.'
      end

      if voucher[:discount][:type] === 'PERCENT'
        discount = voucher[:discount][:percent_off]
        validate_percent_discount(discount);
        price_discount = base_price * (discount / 100.0)
        return round_money(price_discount)

      elsif voucher[:discount][:type] === 'AMOUNT'
        discount = voucher[:discount][:amount_off] / e
        validate_amount_discount(discount)
        new_price = base_price - discount
        return round_money(new_price > 0 ? (discount) : (base_price))

      elsif voucher[:discount][:type] === 'UNIT'
        if !unit_price
          raise 'Missing unit_price argument.'
        end
        discount = voucher[:discount][:unit_off]
        validate_unit_discount(discount)
        price_discount = unit_price * discount
        return round_money(price_discount > base_price ? (base_price) : (price_discount))

      else
        raise 'Unsupported discount type'
      end
    end
  end
end