Венета обнови решението на 05.11.2011 02:28 (преди над 12 години)
+require 'bigdecimal'
+require 'bigdecimal/util'
+
+class Product
+ attr_accessor :name, :price, :discount
+ def initialize(product_name, price, discount = {})
+ @name = product_name
+ @price = price
+ initialize_discount(discount) if discount.length > 0
+ end
+
+ private
+ def initialize_discount(discount)
+ if discount[:get_one_free]
+ @discount = GetOneFreeDiscount.new(discount[:get_one_free])
+ elsif discount[:package]
+ @discount = PackageDiscount.new(discount[:package])
+ elsif discount[:threshold]
+ @discount = ThresholdDiscount.new(discount[:threshold])
+ end
+ end
+
+ def calculate_price(quantity)
+ @price.to_d * quantity
+ end
+
+ def calculate_discount(quantity)
+ @discount ? @discount.calculate_discount(@price, quantity) : 0
+ end
+
+ public
+ def hash
+ @name.hash
+ end
+
+ def eql?(other)
+ @name.eql? other.name
+ end
+
+ def total_price(quantity)
+ calculate_price(quantity) - calculate_discount(quantity)
+ end
+
+ def print(quantity)
+ product_price = calculate_price(quantity)
+ product_inv = "\n| %-38s %7s |%9.2f |" % [@name, quantity, product_price]
+ if @discount
+ product_inv += @discount.print(@price, quantity)
+ end
+ product_inv
+ end
+end
+
+class GetOneFreeDiscount
+ def initialize(discount)
+ @get_one_free = discount
+ end
+
+ def calculate_discount(product_price, quantity)
+ (quantity / @get_one_free) * product_price.to_d
+ end
+
+ def print(product_price, quantity)
+ discount_calc = calculate_discount(product_price, quantity)
+ if discount_calc > 0
+ discount_text = "(buy #{@get_one_free - 1}, get 1 free)"
+ discount_neg = '-'.concat(discount_calc.to_s)
+ "\n| %-45s|%9.2f |" % [discount_text, discount_neg]
+ else
+ ""
+ end
+ end
+end
+
+class PackageDiscount
+ def initialize(discount)
+ @package = discount.keys[0]
+ @percent = discount.values[0]
+ end
+
+ def calculate_discount(product_price, quantity)
+ (quantity / @package) * @package * product_price.to_d * @percent / 100
+ end
+
+ def print(product_price, quantity)
+ discount_calc = calculate_discount(product_price, quantity)
+ if discount_calc > 0
+ discount_text = "(get #{@percent}% off for every #{@package})"
+ discount_neg = '-'.concat(discount_calc.to_s)
+ "\n| %-45s|%9.2f |" % [discount_text, discount_neg]
+ else
+ ""
+ end
+ end
+end
+
+class ThresholdDiscount
+ def initialize(discount)
+ @amount = discount.keys[0]
+ @percent = discount.values[0]
+ end
+
+ def calculate_discount(product_price, quantity)
+ if (quantity > @amount)
+ (quantity - @amount) * product_price.to_d * @percent / 100
+ else
+ 0
+ end
+ end
+
+ def print(product_price, quantity)
+ discount_calc = calculate_discount(product_price, quantity)
+ if discount_calc > 0
+ discount_text = "(#{@percent}% off of every after the #{amount_words})"
+ discount_neg = '-'.concat(discount_calc.to_s)
+ "\n| %-45s|%9.2f |" % [discount_text, discount_neg]
+ else
+ ""
+ end
+ end
+
+ def amount_words
+ if (@amount == 1)
+ "1st"
+ elsif (@amount == 2)
+ "2nd"
+ elsif (@amount == 3)
+ "3rd"
+ else
+ "#{@amount}th"
+ end
+ end
+end
+
+class AmountCoupon
+ attr_accessor :name
+ def initialize(coupon_name, discount)
+ @name = coupon_name
+ @amount = discount.kind_of?(String) ? discount.to_d : discount
+ end
+
+ def calculate_discount(price)
+ @amount < price ? @amount : price
+ end
+
+ def print(price)
+ coupon_discount = calculate_discount(price)
+ discount_text = "Coupon %s - %.2f off" % [@name, @amount]
+ discount_neg = '-'.concat(coupon_discount.to_s)
+ "\n| %-46s | %8.2f |" % [discount_text, discount_neg]
+ end
+end
+
+class PercentCoupon
+ attr_accessor :name
+ def initialize(coupon_name, discount)
+ @name = coupon_name
+ @percent = discount
+ end
+
+ def calculate_discount(price)
+ price * @percent / 100
+ end
+
+ def print(price)
+ coupon_discount = calculate_discount(price)
+ discount_text = "Coupon #{@name} - #{@percent}% off"
+ discount_neg = '-'.concat(coupon_discount.to_s)
+ "\n| %-46s | %8.2f |" % [discount_text, discount_neg]
+ end
+end
+
+class Inventory
+ def initialize
+ @products_registered = []
+ @coupons_registered = []
+ end
+
+ def register(product_name, price, discount = {})
+ raise "Product name is too long" if product_name.length > 40
+ raise "Duplicated product name" if product_registered?(product_name)
+ raise "Invalid product price." if price.to_d < 0.01 or price.to_d > 999.99
+ @products_registered << Product.new(product_name, price, discount)
+ end
+
+ def register_coupon(coupon_name, discount)
+ raise "Duplicated coupon name" if coupon_registered?(coupon_name)
+ if discount[:amount]
+ @coupons_registered << AmountCoupon.new(coupon_name, discount[:amount])
+ elsif discount[:percent]
+ @coupons_registered << PercentCoupon.new(coupon_name, discount[:percent])
+ end
+ end
+
+ def new_cart
+ @cart = Cart.new(self)
+ end
+
+ def product_registered?(product_name)
+ @products_registered.any? { |product| product.name == product_name }
+ end
+
+ def product_by_name(product_name)
+ @products_registered.find(product_name) { |item| item.name == product_name }
+ end
+
+ def coupon_registered?(coupon_name)
+ @coupons_registered.any? { |coupon| coupon.name == coupon_name }
+ end
+
+ def coupon_by_name(coupon_name)
+ @coupons_registered.find(coupon_name) { |item| item.name == coupon_name }
+ end
+end
+
+class Cart
+ def initialize(inventory)
+ @inventory = inventory
+ @products_added = {}
+ end
+
+ private
+ def total_products_price
+ @products_added.inject(0) do |sum, (product, quantity)|
+ sum += product.total_price(quantity)
+ end
+ end
+
+ def total_coupon_discount(price)
+ @coupon_used ? @coupon_used.calculate_discount(price) : 0
+ end
+
+ def build_invoice(total_result, products_price)
+ border = "+" + "-" * 48 + "+" + "-" * 10 + "+"
+ invoice = border
+ invoice += "\n| %-38s %7s |%9s |" % ["Name", "qty", "price"]
+ invoice += "\n" + border
+ invoice += invoice_rows(products_price)
+ invoice += "\n" + border
+ invoice += "\n| %-47s|%9.2f |" % ["TOTAL", total_result]
+ invoice += "\n" + border + "\n"
+ end
+
+ def invoice_rows(products_price)
+ invoice_rows = @products_added.inject("") do |invoice, (product, quantity)|
+ invoice += product.print(quantity)
+ end
+ if @coupon_used
+ invoice_rows += @coupon_used.print(products_price)
+ end
+ invoice_rows
+ end
+
+ public
+ def add(product_name, quantity = 1)
+ unless @inventory.product_registered?(product_name)
+ raise "Product #{product_name} doesn't exist in inventory."
+ end
+ raise "Product quantity 0 or less." if quantity <= 0
+ raise "Product quantity greater than 99." if (quantity > 99)
+ product = @inventory.product_by_name(product_name)
+ @products_added[product] = (@products_added[product] || 0) + quantity
+ end
+
+ def use(coupon_name)
+ unless @inventory.coupon_registered?(coupon_name)
+ raise "Coupon #{coupon_name} doesn't exist in inventory."
+ end
+ @coupon_used = @inventory.coupon_by_name(coupon_name)
+ end
+
+ def total
+ products_price = total_products_price()
+ coupon_discount = total_coupon_discount(products_price)
+ products_price - coupon_discount
+ end
+
+ def invoice
+ products_price = total_products_price()
+ coupon_discount = total_coupon_discount(products_price)
+ build_invoice((products_price - coupon_discount), products_price)
+ end
+end