Михаил обнови решението на 07.11.2011 14:22 (преди около 13 години)
+require 'bigdecimal'
+require 'bigdecimal/util'
+
+class Promotion
+ attr_reader :description
+
+ def initialize key, value
+ send key, value
+ end
+
+ def apply count,price
+ @lambda.call count, price
+ end
+
+private
+ def get_one_free value
+ @description = "(buy #{value-1}, get 1 free)"
+ @lambda = ->(count, price) { return count/value * price }
+ end
+
+ def threshold value
+ percent = value.first[1]/'100'.to_d
+ threshold = value.first[0]
+ @description = "(#{value.first[1]}% off of every after the #{ordinal threshold})"
+ @lambda = ->(count, price) do
+ return count > threshold ? (count - threshold) * price * percent : 0
+ end
+ end
+
+ def package value
+ package = value.first[0]
+ percent = value.first[1]/'100'.to_d
+ @description = "(get #{value.first[1]}% off for every #{value.first[0]})"
+ @lambda = ->(count, price) do
+ if count >= package then
+ on_promo = count - count%package
+ return (price * on_promo * percent)
+ else
+ 0
+ end
+ end
+ end
+
+ def ordinal number
+ result = number.to_s
+ if (number >= 10 and number <= 19)
+ result+="th"
+ elsif (number%10 == 1) then result += "st"
+ elsif (number%10 == 2) then result += "nd"
+ elsif (number%10 == 3) then result += "rd"
+ else result += "th"
+ end
+ result
+ end
+end
+
+class Product
+ attr_reader :name, :price, :promotion
+
+ def initialize name, price, promotion = nil
+ @price = price.to_d
+ raise "too long" if name.length > 40
+ raise "too low" if not ('999.99'.to_d >= @price and @price>= '0.01'.to_d)
+ #TODO constants
+ @name, @price = name, price.to_d
+ @promotion = Promotion.new *promotion.first if promotion
+ end
+
+ def calculate count
+ result = flat_calculate count
+ result -= discount count
+ result
+ end
+
+ def discount count
+ promotion != nil ? promotion.apply(count, price) : 0
+ end
+
+ def flat_calculate count
+ price * count
+ end
+
+ def eql? (other)
+ name == other.name
+ end
+
+ alias :== :eql?
+
+ def hash
+ name.hash
+ end
+
+ alias :to_hash :hash
+end
+
+class Coupon
+ attr_reader :name, :description, :info
+
+ def initialize name, description
+ @name,@description = name, description
+ @info = "Coupon " + name + " - "
+ @info << "%d%% off" % description.first[1] if description[:percent]
+ @info << "%-.2f off" % description.first[1] if description[:amount]
+ end
+
+ def apply price
+ return -(price * description[:percent]/'100'.to_d) if description[:percent]
+ return -price if description[:amount] and description[:amount].to_d > price
+ return -description[:amount].to_d if description[:amount]
+ end
+end
+
+class Inventory
+ def initialize
+ @items = {}
+ @coupons = {}
+ end
+ def register(name, cost, promotion = nil)
+ raise "exist" if @items[name]
+ @items[name] = Product.new(name, cost, promotion)
+ end
+
+ def register_coupon name, description
+ raise "exist" if @coupons[name]
+ @coupons[name] = Coupon.new(name, description)
+ end
+
+ def new_cart
+ Cart.new method(:get_item), method(:get_coupon)
+ end
+
+ def get_item name
+ @items[name]
+ end
+
+ def get_coupon name
+ @coupons[name]
+ end
+end
+
+class Cart
+ def initialize get_item, get_coupon
+ @get_item, @get_coupon = get_item, get_coupon
+ @items = Hash.new(0)
+ @coupon = nil
+ end
+
+ def add name, count = 1
+ raise "negative" if count < 1
+ item = @get_item.call name
+ raise "Missing Error" if not item
+ raise "Sexist Error" if @items[item] + count > 99
+ @items[item] += count
+ end
+
+ def use name
+ coupon = @get_coupon.call name
+ raise "Missing Error" if not coupon
+ raise "Sexist Error2" if @coupon
+ @coupon = coupon
+ end
+
+ def total
+ return total_invoice[0]
+ end
+
+
+ def invoice
+ return total_invoice[1]
+ end
+
+private
+ NEWHEAD =<<LINES
++------------------------------------------------+----------+
+| Name qty | price |
++------------------------------------------------+----------+
+LINES
+
+ InvoiceEnd =<<LINES
++------------------------------------------------+----------+
+| TOTAL | %8.2f |
++------------------------------------------------+----------+
+LINES
+
+ def item_info item
+ result = [item.name, @items[item]]
+ result << item.flat_calculate(result[1])
+ if item.promotion then
+ promotion = item.promotion
+ result += [promotion.description, -promotion.apply(@items[item], item.price)]
+ end
+ result
+ end
+
+ def item_invoice info
+ result = "| %-42s%4d | %8.2f |\n" % info
+ result << "| %-44s | %8.2f |\n" % info[3..4] if info.size == 5
+ result
+ end
+
+ def coupon_invoice info
+ "| %-46s | %8.2f |\n" % info
+ end
+
+ def total_invoice
+ result, invoice = '0'.to_d, NEWHEAD.clone
+ result, invoice = [result, invoice].zip(total_invoice_items).map { |i| i.inject(&:+) }
+ if @coupon
+ info = [@coupon.info, @coupon.apply(result)]
+ invoice << coupon_invoice(info)
+ result += info[1]
+ end
+ invoice << InvoiceEnd % result
+ [result, invoice]
+ end
+
+ def total_invoice_items
+ result, invoice = '0'.to_d, ""
+ @items.keys.map { |item| item_info(item) }.each do |info|
+ invoice << item_invoice(info)
+ result += info[2]
+ result += info[4] if info[4]
+ end
+ [result, invoice]
+ end
+end