task three

day_2/tn_rails_concurrent/Gemfile

@@ -26,3 +26,4 @@ gem "parallel", "~> 1.26.3"
 gem "sidekiq", "~> 7.3.6"
 
 gem "activerecord-import", "~> 2.0"
+gem "active_model_serializers"

day_2/tn_rails_concurrent/Gemfile.lock

@@ -50,6 +50,11 @@ GEM
       erubi (~> 1.11)
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
+    active_model_serializers (0.10.15)
+      actionpack (>= 4.1)
+      activemodel (>= 4.1)
+      case_transform (>= 0.2)
+      jsonapi-renderer (>= 0.1.1.beta1, < 0.3)
     activejob (7.1.5.1)
       activesupport (= 7.1.5.1)
       globalid (>= 0.3.6)
@@ -90,6 +95,8 @@ GEM
     bootsnap (1.18.4)
       msgpack (~> 1.2)
     builder (3.3.0)
+    case_transform (0.2)
+      activesupport
     concurrent-ruby (1.3.4)
     connection_pool (2.4.1)
     crass (1.0.6)
@@ -111,6 +118,7 @@ GEM
     irb (1.14.2)
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
+    jsonapi-renderer (0.2.2)
     logger (1.6.3)
     loofah (2.23.1)
       crass (~> 1.0.2)
@@ -233,6 +241,7 @@ PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
+  active_model_serializers
   activerecord-import (~> 2.0)
   annotate
   bootsnap

day_2/tn_rails_concurrent/app/controllers/orders_controller.rb

@@ -1,6 +1,6 @@
 class OrdersController < ApplicationController
   def top_products_report
-    top_products = Order.all
-    render json: top_products
+    top_products = ProductsByOrdersCount.new.call
+    render json: top_products, each_serializer: TopProductsSerializer
   end
 end

day_2/tn_rails_concurrent/app/models/order.rb

@@ -10,7 +10,7 @@
 #  updated_at     :datetime         not null
 #
 class Order < ApplicationRecord
-  belongs_to :product
+  belongs_to :product, counter_cache: true
 
   scope :pending, -> { where(current_status: :pending) }
   scope :processed, -> { where(current_status: :processed) }

day_2/tn_rails_concurrent/app/queries/products_by_orders_count.rb

@@ -0,0 +1,43 @@
+class ProductsByOrdersCount
+  def initialize(count: 10)
+    @count = count
+  end
+
+  def call
+    sanitized_sql = ActiveRecord::Base.sanitize_sql_array([sql, count, count])
+    Product.find_by_sql(sanitized_sql)
+  end
+
+  private
+
+  attr_reader :count
+
+  def sql
+    @sql ||= <<-SQL.squish
+      WITH top_products AS (
+        SELECT *
+        FROM products
+        ORDER BY orders_count DESC
+        LIMIT ?
+      ),
+      max_days AS (
+        SELECT product_id, DATE(created_at) AS order_date, SUM(quantity) AS daily_quantity
+        FROM orders
+        WHERE product_id IN (SELECT product_id FROM top_products)
+        GROUP BY product_id, DATE(created_at)
+      ),
+      max_days_per_product AS (
+        SELECT product_id, order_date, daily_quantity,
+              RANK() OVER (PARTITION BY product_id ORDER BY daily_quantity DESC) as rank
+        FROM max_days
+      )
+
+      SELECT t.*, m.order_date as date
+      FROM max_days_per_product as m
+      JOIN top_products as t ON t.id = m.product_id
+      WHERE m.rank = 1
+      ORDER BY t.orders_count DESC
+      LIMIT ?;
+    SQL
+  end
+end

day_2/tn_rails_concurrent/app/serializers/top_products_serializer.rb

@@ -0,0 +1,7 @@
+class TopProductsSerializer < ActiveModel::Serializer
+  attributes :product_id, :date, :total_quantity
+
+  def product_id = self.object.id
+  def total_quantity = self.object.orders_count
+  def date = self.object.date.strftime("%d-%m-%Y")
+end

day_2/tn_rails_concurrent/db/migrate/20241227185054_add_orders_count_to_products.rb

@@ -0,0 +1,5 @@
+class AddOrdersCountToProducts < ActiveRecord::Migration[7.1]
+  def change
+    add_column :products, :orders_count, :integer, default: 0, null: false
+  end
+end

day_2/tn_rails_concurrent/db/seeds.rb

@@ -3,14 +3,14 @@
 Product.destroy_all
 puts "Products destroyed"
 
-Product.insert_all(Array.new(100) { { name: "Product #{rand(1..1000)}", stock: rand(1..50), price: rand(10..100) } })
+Product.insert_all(Array.new(100_000) { { name: "Product #{rand(1..100_000_000)}", stock: rand(1..50_00), price: rand(10..100_000) } })
 puts "Products created: #{Product.count}"
 
 product_ids = Product.pluck(:id)
 statuses = ["pending", "processed", "cancelled"]
 dates = (1..30).map { |n| n.days.ago }
 ActiveRecord::Base.record_timestamps = false
-Order.insert_all(Array.new(20_000) {
+Order.insert_all(Array.new(100_000_000) {
   {
     product_id: product_ids.sample, quantity: rand(1..10),
     current_status: statuses.sample,

day_2/tn_rails_concurrent/db/structure.sql

@@ -79,7 +79,8 @@ CREATE TABLE public.products (
     stock integer,
     price numeric,
     created_at timestamp(6) without time zone NOT NULL,
-    updated_at timestamp(6) without time zone NOT NULL
+    updated_at timestamp(6) without time zone NOT NULL,
+    orders_count integer DEFAULT 0 NOT NULL
 );
 
 
@@ -164,6 +165,7 @@ ALTER TABLE ONLY public.schema_migrations
 SET search_path TO "$user", public;
 
 INSERT INTO "schema_migrations" (version) VALUES
+('20241227185054'),
 ('20241216120643'),
 ('20241216120641');