Борис обнови решението на 07.11.2011 11:12 (преди над 12 години)
+require 'bigdecimal'
+require 'bigdecimal/util'
+require 'singleton'
+
+class Product
+ attr_reader :name
+ attr_reader :price
+
+ def initialize(name, price)
+ @name = name
+ @price = price
+ end
+end
+
+class Inventory
+ attr_reader :products
+ attr_reader :promotion_per_product
+ attr_reader :coupon_by_name
+
+ def initialize
+ @products = Array.new
+ @promotion_per_product = Hash.new
+ @coupon_by_name = Hash.new
+ end
+
+ def register(name, price, promotion = nil)
+ if name.length > 40
+ raise "Product name exceeds 40 symbols"
+ end
+ unless price.to_d.between? 0.01, 999.99
+ raise "Price not in the range of 0.01 and 999.99"
+ end
+ if @products and @products.any? { |product| product.name == name }
+ raise "Product already exists"
+ end
+
+ @products << Product.new(name, price)
+ @promotion_per_product[@products.last] = promotion if promotion
+ end
+
+ def new_cart
+ Cart.new(self)
+ end
+
+ def register_coupon(name, info)
+ # TODO coupons vs. coupon_by_name
+ @coupon_by_name[name] = info
+ end
+
+ def get_product(name)
+ @products.find { |product| product.name == name }
+ end
+end
+
+class Cart
+ attr_reader :inventory
+ attr_reader :quantity_per_product
+ attr_reader :coupon_name
+ attr_reader :coupon_type
+ attr_reader :coupon_info
+
+ def initialize(inventory)
+ @inventory = inventory
+ @quantity_per_product = Hash.new(0)
+ end
+
+ def add(name, quantity = 1)
+ product = @inventory.get_product(name)
+
+ unless product
+ raise "Name already exists"
+ end
+ if @quantity_per_product[product] + quantity <= 0
+ raise "Quantity should be a positive number"
+ end
+ if @quantity_per_product[product] + quantity > 99
+ raise "Quantity should be less or equal to 99"
+ end
+
+ @quantity_per_product[product] += quantity
+ end
+
+ def total
+ sum = total_without_coupon
+ coupon = CouponFactory.get_coupon(@coupon_type, @coupon_info)
+ if coupon
+ sum -= coupon.discount(sum)
+ else
+ sum
+ end
+ end
+
+ def total_without_coupon
+ @quantity_per_product.inject(0) do |sum, (product, quantity)|
+ promotion = @inventory.promotion_per_product[product]
+ if promotion
+ promo = PromotionFactory.get_promotion(promotion.keys[0], promotion)
+ sum -= promo.discount(product.price, quantity)
+ end
+ sum + product.price.to_d * quantity
+ end
+ end
+
+ def invoice
+ result = Invoice.header
+
+ @quantity_per_product.each do |product, quantity|
+ price = product.price.to_d * quantity
+
+ result += Invoice.line_for_product(product.name, quantity, price)
+ promo = @inventory.promotion_per_product[product]
+ if promo
+ result += Invoice.line_for_promotion(product.price, quantity, product, promo)
+ end
+ end
+
+ result += coupon_line + Invoice.footer(total)
+ end
+
+ def coupon_line
+ Invoice.line_coupon(@coupon_name, @coupon_type, @coupon_info, total_without_coupon)
+ end
+
+ def use(coupon_name)
+ raise "Coupon name does not exist" unless @inventory.coupon_by_name[coupon_name]
+
+ @coupon_name = coupon_name
+ @coupon_type = @inventory.coupon_by_name[coupon_name].keys[0]
+ @coupon_info = @inventory.coupon_by_name[coupon_name].values[0]
+ end
+end
+
+class Invoice
+ include Singleton
+
+ def self.line
+ "+------------------------------------------------+----------+\n"
+ end
+
+ def self.header
+ res = line
+ res << "| Name qty | price |\n"
+ res += line
+ end
+
+ def self.footer(sum)
+ res = line
+ res << "| TOTAL |" + "%9.2f" % [sum] + " |\n"
+ res += line
+ end
+
+ def self.line_for_product(name, quantity, price)
+ result = String.new
+ result += "| " + name + " " * (44 - name.length)
+ result += " " * (2 - quantity.to_s.length) + quantity.to_s + " |"
+ result += "%9.2f" % [price] + " |\n"
+ end
+
+ def self.line_for_promotion(price, quantity, product, promotion)
+ result = String.new
+ promo = PromotionFactory.get_promotion(promotion.keys[0], promotion)
+ if promo
+ discount = "-" + "%0.2f" % [promo.discount(price, quantity)]
+ result += "| " + promo.to_s + " " * (47 - promo.to_s.length) + "|"
+ result += " " * (9 - discount.length) + discount + " |" + "\n"
+ end
+ end
+
+ def self.line_coupon(name, type, info, total)
+ result = String.new
+ if name
+ coupon = CouponFactory.get_coupon(type, info)
+ coupon_str = "Coupon " + name + " " + "#{coupon.to_s}"
+ coupon_dis = "-" + "%0.2f" % [coupon.discount(total)]
+ result += "| " + coupon_str + " " * (47 - coupon_str.length) + "|"
+ result += " " * (9 - coupon_dis.length) + coupon_dis + " |" + "\n"
+ end
+ result
+ end
+end
+
+module Coupon
+ def initialize(coupon_info)
+ @coupon_info = coupon_info
+ end
+
+ #too sexy for Java interfaces
+ def discount
+ raise NotImplementedError.new
+ end
+
+ class Percent
+ include Coupon
+
+ def discount(sum)
+ sum * @coupon_info / 100.0
+ end
+ end
+
+ def to_s
+ "- #{@coupon_info}% off"
+ end
+
+ class Amount
+ include Coupon
+
+ def discount(sum)
+ sum > @coupon_info ? @coupon_info : sum
+ end
+
+ def to_s
+ a = "%0.2f" % [@coupon_info]
+ "- #{a} off"
+ end
+ end
+end
+
+class CouponFactory
+ include Singleton
+
+ def self.get_coupon(type, coupon_info)
+ case type
+ when :percent
+ Coupon::Percent.new(coupon_info)
+ when :amount
+ Coupon::Amount.new(coupon_info)
+ end
+ end
+end
+
+module Promotion
+ def initialize(promo_info)
+ @promo_info = promo_info
+ end
+
+ #too sexy for Java interfaces
+ def discount(price, quantity)
+ raise NotImplementedError.new
+ end
+
+ class GetOnFree
+ include Promotion
+
+ def discount(price, quantity)
+ free_items_count = quantity / @promo_info.values[0]
+ price.to_d * free_items_count
+ end
+
+ def to_s
+ " (buy #{@promo_info.values[0] - 1}, get 1 free)"
+ end
+ end
+
+ class Package
+ include Promotion
+
+ def discount(price, quantity)
+ count = @promo_info.values[0].keys[0]
+ result = BigDecimal(@promo_info.values[0].values[0].to_s)
+ (quantity / count) * (count * price.to_d * (result / 100))
+ end
+
+ def to_s
+ a = BigDecimal(@promo_info.values[0].values[0].to_s)
+ " (get #{a.to_i}% off for every #{@promo_info.values[0].keys[0]})"
+ end
+ end
+
+ class Threshold
+ include Promotion
+
+ def discount(price, quantity)
+ count = @promo_info.values[0].keys[0]
+ result = BigDecimal(@promo_info.values[0].values[0].to_s)
+ extra = quantity > count ? quantity - count : 0
+ extra * price.to_d * (result / 100)
+ end
+
+ def to_s
+ count = @promo_info.values[0].keys[0]
+ a = BigDecimal(@promo_info.values[0].values[0].to_s)
+ postfix = number_postfix(count)
+ " (#{a.to_i}% off of every after the #{count}#{postfix})"
+ end
+
+ def number_postfix(number)
+ case number
+ when 1 then return "st"
+ when 2 then return "nd"
+ when 3 then return "rd"
+ end
+ return "th"
+ end
+ end
+end
+
+class PromotionFactory
+ include Singleton
+
+ def self.get_promotion(name, promotion)
+ case name
+ when :get_one_free
+ Promotion::GetOnFree.new(promotion)
+ when :package
+ Promotion::Package.new(promotion)
+ when :threshold
+ Promotion::Threshold.new(promotion)
+ end
+ end
+end