Add discount priority indicating discount apply order

lib/basket.rb

@@ -34,7 +34,7 @@ def show
       end
     end
     puts '------------------------------------------'
-    output_total = ('$' + total.round(2).to_s).rjust(8)
-    puts "    \t\t    \t\t  #{output_total}"
+    output_format = format('$%.2f', total).rjust(8)
+    puts "    \t\t    \t\t  #{output_format}"
   end
 end

lib/checkout.rb

@@ -28,7 +28,7 @@ def show
 
   def total
     @items.each(&:reset)
-    @sales_rules.each { |rule| rule.apply(@items) }
+    @sales_rules.sort_by(&:priority).each { |rule| rule.apply(@items) }
     @basket.total = @items.inject(0.0) { |total, item| total + item.price }.round(2)
   end
 

lib/discounts/base_discount.rb

@@ -1,7 +1,8 @@
 class BaseDiscount
-  attr_reader :discount_type
+  attr_reader :priority
 
   @discount_type = ''
+  @priority = 0
   @decription = ''
   @min_items = 1
   @limit = nil

lib/discounts/buy_this_get_that_percent_discount.rb

@@ -1,9 +1,10 @@
 require_relative '../discounts/base_discount'
 
 class BuyThisGetThatPercentDiscount < BaseDiscount
-  def initialize(discount_type:, description: '', this_code:, this_min_items: 1, that_code:, that_max_items: 1, percent_discount:, limit: nil)
+  def initialize(discount_type:, description: '', priority:, this_code:, this_min_items: 1, that_code:, that_max_items: 1, percent_discount:, limit: nil)
     @discount_type = discount_type
     @description = description
+    @priority = priority
     @this_code = this_code
     @this_min_items = this_min_items
     @that_code = that_code

lib/discounts/item_discount.rb

@@ -1,9 +1,10 @@
 require_relative '../discounts/base_discount'
 
 class ItemDiscount < BaseDiscount
-  def initialize(discount_type:, description: '', code:, min_items:, discount:, limit: nil)
+  def initialize(discount_type:, description: '', priority:, code:, min_items:, discount:, limit: nil)
     @discount_type = discount_type
     @description = description
+    @priority = priority
     @code = code
     @min_items = min_items
     @discount = discount
@@ -18,13 +19,15 @@ def apply(items)
   private
 
   def apply_discount(orders)
+    count = 0
     discount_amount = @discount / @min_items
-    orders.each_with_index do |order, i|
-      next unless i < @min_items && order.discount_type.empty?
+    orders.each do |order|
+      next unless count < @min_items && order.discount_type.empty?
 
       order.discount_type = @discount_type
       order.discount_amount = discount_amount
       order.price -= discount_amount
+      count += 1
     end
     orders
   end

lib/discounts/two_for_one_discount.rb

@@ -1,9 +1,10 @@
 require_relative '../discounts/base_discount'
 
 class TwoForOneDiscount < BaseDiscount
-  def initialize(discount_type:, description: '', code:, limit: nil)
+  def initialize(discount_type:, description: '', priority:, code:, limit: nil)
     @discount_type = discount_type
     @description = description
+    @priority = priority
     @code = code
     @min_items = 2
     @limit = limit

spec/checkout_spec.rb

@@ -9,12 +9,16 @@
 describe Checkout do
   subject(:checkout) do
     sales_rules = [
-      TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1'),
-      ItemDiscount.new(discount_type: 'APPL', code: 'AP1', min_items: 3, discount: 4.50),
-      BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', this_code: 'CH1', this_min_items: 1,
-                                        that_code: 'MK1', that_max_items: 1, percent_discount: 100, limit: 1),
-      BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', this_code: 'OM1', this_min_items: 1,
-                                        that_code: 'AP1', that_max_items: 1, percent_discount: 50)
+      TwoForOneDiscount.new(discount_type: 'BOGO', priority: 3, code: 'CF1'),
+      ItemDiscount.new(discount_type: 'APPL', priority: 2, code: 'AP1', min_items: 3, discount: 4.50),
+      BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', priority: 4,
+                                        this_code: 'CH1', this_min_items: 1,
+                                        that_code: 'MK1', that_max_items: 1,
+                                        percent_discount: 100, limit: 1),
+      BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', priority: 1,
+                                        this_code: 'OM1', this_min_items: 1,
+                                        that_code: 'AP1', that_max_items: 1,
+                                        percent_discount: 50)
     ]
     products = [
       Product.new('CH1', 'Chai', 3.11),
@@ -53,20 +57,6 @@
     end
 
     context 'when basket is not empty and no discounts' do
-      subject(:checkout) do
-        sales_rules = []
-        products = [
-          Product.new('CH1', 'Chai', 3.11),
-          Product.new('AP1', 'Apples', 6.00),
-          Product.new('CF1', 'Coffee', 11.23),
-          Product.new('MK1', 'Milk', 4.75),
-          Product.new('OM1', 'Oatmeal', 3.69)
-        ]
-        store = Store.new(sales_rules, products)
-
-        Checkout.new(store)
-      end
-
       it 'returns a nonzero total' do
         checkout.scan('CH1')
         checkout.scan('AP1')
@@ -76,8 +66,7 @@
         items = [
           Item.new('CH1', 3.11),
           Item.new('AP1', 6.00),
-          Item.new('CF1', 11.23),
-          Item.new('MK1', 4.75)
+          Item.new('CF1', 11.23)
         ]
         total = items.inject(0.0) { |sum, item| sum + item.price }
 
@@ -86,27 +75,6 @@
     end
 
     context 'when basket has sale items' do
-      subject(:checkout) do
-        sales_rules = [
-          TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1'),
-          ItemDiscount.new(discount_type: 'APPL', code: 'AP1', min_items: 3, discount: 4.50),
-          BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', this_code: 'CH1', this_min_items: 1,
-                                            that_code: 'MK1', that_max_items: 1, percent_discount: 100, limit: 1),
-          BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', this_code: 'OM1', this_min_items: 1,
-                                            that_code: 'AP1', that_max_items: 1, percent_discount: 50)
-        ]
-        products = [
-          Product.new('CH1', 'Chai', 3.11),
-          Product.new('AP1', 'Apples', 6.00),
-          Product.new('CF1', 'Coffee', 11.23),
-          Product.new('MK1', 'Milk', 4.75),
-          Product.new('OM1', 'Oatmeal', 3.69)
-        ]
-        store = Store.new(sales_rules, products)
-
-        Checkout.new(store)
-      end
-
       it 'applies buy chai get milk free discount' do
         checkout.scan('CH1')
         checkout.scan('AP1')
@@ -159,7 +127,26 @@
         checkout.show
       end
 
-      it 'applies 3+ apples get $4.50 discount' do
+      it 'applies one get one free discount' do
+        checkout.scan('CF1')
+        checkout.scan('CH1')
+        checkout.scan('CH1')
+        checkout.scan('CF1')
+        checkout.scan('CH1')
+        checkout.scan('CF1')
+        checkout.scan('CH1')
+        checkout.scan('CF1')
+        checkout.scan('CH1')
+        checkout.scan('CF1')
+        checkout.scan('CH1')
+        checkout.scan('CF1')
+        checkout.scan('CF1')
+        checkout.show
+
+        expect(checkout.total).to eq(63.58)
+      end
+
+      it 'applies 3 apples get $4.50 discount' do
         checkout.scan('AP1')
         checkout.scan('AP1')
         checkout.scan('CH1')
@@ -179,6 +166,18 @@
         checkout.show
       end
 
+      it 'applies 3 or more (5) apples get $4.50 discount' do
+        checkout.scan('AP1')
+        checkout.scan('AP1')
+        checkout.scan('CH1')
+        checkout.scan('AP1')
+        checkout.scan('AP1')
+        checkout.scan('AP1')
+        checkout.show
+
+        expect(checkout.total).to eq(28.61)
+      end
+
       it 'applies buy oakmeal get 50% off apple discount' do
         checkout.scan('OM1')
         checkout.scan('AP1')
@@ -199,6 +198,18 @@
 
         checkout.show
       end
+
+      it 'applies both 3+ apples get $4.50 discount and buy oakmeal get 50% off apple discount' do
+        checkout.scan('AP1')
+        checkout.scan('AP1')
+        checkout.scan('CH1')
+        checkout.scan('AP1')
+        checkout.scan('OM1')
+        checkout.scan('AP1')
+        checkout.show
+
+        expect(checkout.total).to eq(23.30)
+      end
     end
   end
 

spec/discounts/buy_this_get_that_percent_discount_spec.rb

@@ -3,7 +3,7 @@
 
 describe BuyThisGetThatPercentDiscount do
   subject(:buy_this_get_that_percent_discount) do
-    BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', this_code: 'CH1',
+    BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', priority: 4, this_code: 'CH1',
                                       that_code: 'MK1', percent_discount: 100, limit: 1)
   end
 
@@ -56,7 +56,7 @@
   describe '#apply_discount (private method)' do
     context 'when min this items and max that items are met and unlimited' do
       subject(:buy_this_get_that_percent_discount) do
-        BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', this_code: 'OM1',
+        BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', priority: 4, this_code: 'OM1',
                                           that_code: 'AP1', percent_discount: 50)
       end
 
@@ -187,7 +187,7 @@
 
     context 'when that item is 50% off unlimited offer' do
       subject(:buy_this_get_that_percent_discount) do
-        BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', this_code: 'OM1',
+        BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', priority: 4, this_code: 'OM1',
                                           that_code: 'AP1', percent_discount: 50)
       end
 

spec/discounts/item_discount_spec.rb

@@ -2,7 +2,7 @@
 require_relative '../../lib/item'
 
 describe ItemDiscount do
-  subject(:item_discount) { ItemDiscount.new(discount_type: 'APPL', code: 'AP1', min_items: 3, discount: 4.50) }
+  subject(:item_discount) { ItemDiscount.new(discount_type: 'APPL', priority: 2, code: 'AP1', min_items: 3, discount: 4.50) }
 
   describe '#apply_discount? (private)' do
     context 'when min items is met' do

spec/discounts/two_for_one_discount_spec.rb

@@ -2,7 +2,7 @@
 require_relative '../../lib/item'
 
 describe TwoForOneDiscount do
-  subject(:two_for_one_discount) { TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1') }
+  subject(:two_for_one_discount) { TwoForOneDiscount.new(discount_type: 'BOGO', priority: 3, code: 'CF1') }
 
   describe '#apply_discount? (private)' do
     context 'when min items is met' do
@@ -65,7 +65,7 @@
 
     context 'when min items is met and limit one offer' do
       let(:limit) { 1 }
-      subject(:two_for_one_discount) { TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1', limit: limit) }
+      subject(:two_for_one_discount) { TwoForOneDiscount.new(discount_type: 'BOGO', priority: 3, code: 'CF1', limit: limit) }
 
       it 'returns just the 1st order with 2nd item free' do
         orders = two_for_one_discount.send(:apply_discount, @orders)

spec/store_spec.rb

@@ -6,15 +6,16 @@
 describe Store do
   subject(:store) do
     sales_rules = [
-      TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1'),
-      ItemDiscount.new(discount_type: 'APPL', code: 'AP1', min_items: 3, discount: 4.50),
-      BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK',
+      TwoForOneDiscount.new(discount_type: 'BOGO', priority: 3, code: 'CF1'),
+      ItemDiscount.new(discount_type: 'APPL', priority: 2, code: 'AP1', min_items: 3, discount: 4.50),
+      BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', priority: 4,
                                         this_code: 'CH1', this_min_items: 1,
                                         that_code: 'MK1', that_max_items: 1,
                                         percent_discount: 100, limit: 1),
-      BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', this_code: 'OM1',
-                                        this_min_items: 1, that_code: 'AP1',
-                                        that_max_items: 1, percent_discount: 50)
+      BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', priority: 1,
+                                        this_code: 'OM1', this_min_items: 1,
+                                        that_code: 'AP1', that_max_items: 1,
+                                        percent_discount: 50)
     ]
     products = [
       Product.new('CH1', 'Chai', 3.11),

yacs_register.rb

@@ -16,15 +16,15 @@ def newline
 end
 
 sales_rules = [
-  TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1',
+  TwoForOneDiscount.new(discount_type: 'BOGO', code: 'CF1', priority: 3,
                         description: 'Buy-One-Get-One-Free Special on Coffee. (Unlimited)'),
-  ItemDiscount.new(discount_type: 'APPL', code: 'AP1', min_items: 3, discount: 4.50,
+  ItemDiscount.new(discount_type: 'APPL', code: 'AP1', min_items: 3, discount: 4.50, priority: 2,
                    description: 'If you buy 3 or more bags of Apples, the price drops to $4.50'),
-  BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', this_code: 'CH1', this_min_items: 1,
-                                    that_code: 'MK1', that_max_items: 1, percent_discount: 100, limit: 1,
+  BuyThisGetThatPercentDiscount.new(discount_type: 'CHMK', this_code: 'CH1', this_min_items: 1, that_code: 'MK1',
+                                    that_max_items: 1, percent_discount: 100, limit: 1, priority: 4,
                                     description: 'Purchase a box of Chai and get milk free. (Limit 1)'),
   BuyThisGetThatPercentDiscount.new(discount_type: 'APOM', this_code: 'OM1', this_min_items: 1,
-                                    that_code: 'AP1', that_max_items: 1, percent_discount: 50,
+                                    that_code: 'AP1', that_max_items: 1, percent_discount: 50, priority: 1,
                                     description: 'Purchase a bag of Oatmeal and get 50% off a bag of Apples')
 ]
 products = [