From 4f852ea3de80534957fb0e508a10f20123421315 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Mon, 8 Apr 2019 06:56:06 +0200
Subject: [PATCH 01/14] Setup the project

---
 lecture_4/homework/.rubocop.yml | 2 ++
 lecture_4/homework/Gemfile      | 2 ++
 lecture_4/homework/Gemfile.lock | 5 +++++
 3 files changed, 9 insertions(+)

diff --git a/lecture_4/homework/.rubocop.yml b/lecture_4/homework/.rubocop.yml
index b9797cb5..b820ed41 100644
--- a/lecture_4/homework/.rubocop.yml
+++ b/lecture_4/homework/.rubocop.yml
@@ -1,3 +1,5 @@
+require: rubocop-performance
+
 AllCops:
   Exclude:
     - bin/**/*
diff --git a/lecture_4/homework/Gemfile b/lecture_4/homework/Gemfile
index b742cedc..57f69fc7 100644
--- a/lecture_4/homework/Gemfile
+++ b/lecture_4/homework/Gemfile
@@ -5,12 +5,14 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 ruby '2.6.2'
 
+gem 'awesome_print'
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.2.2'
 # Use pg as the database for Active Record
 gem 'pg'
 # Use Puma as the app server
 gem 'puma', '~> 3.11'
+gem 'rubocop-performance'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.5'
 # Use Redis adapter to run Action Cable in production
diff --git a/lecture_4/homework/Gemfile.lock b/lecture_4/homework/Gemfile.lock
index cfb773d4..4e178f2b 100644
--- a/lecture_4/homework/Gemfile.lock
+++ b/lecture_4/homework/Gemfile.lock
@@ -49,6 +49,7 @@ GEM
       tzinfo (~> 1.1)
     arel (9.0.0)
     ast (2.4.0)
+    awesome_print (1.8.0)
     bootsnap (1.4.1)
       msgpack (~> 1.0)
     builder (3.2.3)
@@ -131,6 +132,8 @@ GEM
       rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 1.6)
+    rubocop-performance (1.0.0)
+      rubocop (>= 0.58.0)
     ruby-progressbar (1.10.0)
     ruby_dep (1.5.0)
     spring (2.0.2)
@@ -159,6 +162,7 @@ PLATFORMS
 
 DEPENDENCIES
   active_model_serializers
+  awesome_print
   bootsnap (>= 1.1.0)
   byebug
   listen (>= 3.0.5, < 3.2)
@@ -166,6 +170,7 @@ DEPENDENCIES
   puma (~> 3.11)
   rails (~> 5.2.2)
   rubocop
+  rubocop-performance
   spring
   spring-watcher-listen (~> 2.0.0)
   tzinfo-data

From b84eace1e1178a2e6234fc20428dd3ee6f0f189c Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Tue, 9 Apr 2019 06:27:13 +0200
Subject: [PATCH 02/14] Setup Sentry and fix rubocop issues except for
 mercenaries controller file

---
 lecture_4/homework/Gemfile                    |  1 +
 lecture_4/homework/Gemfile.lock               |  6 ++++++
 .../app/controllers/application_controller.rb |  9 +++++++++
 .../controllers/clans/warriors_controller.rb  |  2 +-
 .../app/controllers/errors_controller.rb      |  7 +++++++
 lecture_4/homework/config/application.rb      |  1 +
 .../homework/config/initializers/sentry.rb    |  4 ++++
 .../homework/lib/exceptions/exceptions.rb     | 20 +++++++++++++++++++
 .../controllers/errors_controller_test.rb     |  9 +++++++++
 9 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 lecture_4/homework/app/controllers/errors_controller.rb
 create mode 100644 lecture_4/homework/config/initializers/sentry.rb
 create mode 100644 lecture_4/homework/lib/exceptions/exceptions.rb
 create mode 100644 lecture_4/homework/test/controllers/errors_controller_test.rb

diff --git a/lecture_4/homework/Gemfile b/lecture_4/homework/Gemfile
index 57f69fc7..029954bc 100644
--- a/lecture_4/homework/Gemfile
+++ b/lecture_4/homework/Gemfile
@@ -13,6 +13,7 @@ gem 'pg'
 # Use Puma as the app server
 gem 'puma', '~> 3.11'
 gem 'rubocop-performance'
+gem 'sentry-raven'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.5'
 # Use Redis adapter to run Action Cable in production
diff --git a/lecture_4/homework/Gemfile.lock b/lecture_4/homework/Gemfile.lock
index 4e178f2b..6cbf013e 100644
--- a/lecture_4/homework/Gemfile.lock
+++ b/lecture_4/homework/Gemfile.lock
@@ -59,6 +59,8 @@ GEM
     concurrent-ruby (1.1.5)
     crass (1.0.4)
     erubi (1.8.0)
+    faraday (0.15.4)
+      multipart-post (>= 1.2, < 3)
     ffi (1.10.0)
     globalid (0.4.2)
       activesupport (>= 4.2.0)
@@ -83,6 +85,7 @@ GEM
     mini_portile2 (2.4.0)
     minitest (5.11.3)
     msgpack (1.2.9)
+    multipart-post (2.0.0)
     nio4r (2.3.1)
     nokogiri (1.10.1)
       mini_portile2 (~> 2.4.0)
@@ -136,6 +139,8 @@ GEM
       rubocop (>= 0.58.0)
     ruby-progressbar (1.10.0)
     ruby_dep (1.5.0)
+    sentry-raven (2.9.0)
+      faraday (>= 0.7.6, < 1.0)
     spring (2.0.2)
       activesupport (>= 4.2)
     spring-watcher-listen (2.0.1)
@@ -171,6 +176,7 @@ DEPENDENCIES
   rails (~> 5.2.2)
   rubocop
   rubocop-performance
+  sentry-raven
   spring
   spring-watcher-listen (~> 2.0.0)
   tzinfo-data
diff --git a/lecture_4/homework/app/controllers/application_controller.rb b/lecture_4/homework/app/controllers/application_controller.rb
index 5f846d87..5cb1656c 100644
--- a/lecture_4/homework/app/controllers/application_controller.rb
+++ b/lecture_4/homework/app/controllers/application_controller.rb
@@ -2,4 +2,13 @@
 
 class ApplicationController < ActionController::API
   include ErrorsHandler
+
+  before_action :set_raven_context
+
+  private
+
+  def set_raven_context
+    Raven.user_context(id: session[:current_user_id]) # or anything else in session
+    Raven.extra_context(params: params.to_unsafe_h, url: request.url)
+  end
 end
diff --git a/lecture_4/homework/app/controllers/clans/warriors_controller.rb b/lecture_4/homework/app/controllers/clans/warriors_controller.rb
index 6ccf3ff9..acab2d6a 100644
--- a/lecture_4/homework/app/controllers/clans/warriors_controller.rb
+++ b/lecture_4/homework/app/controllers/clans/warriors_controller.rb
@@ -10,7 +10,7 @@ def index
       warriors = clan.warriors
 
       if params.key?(:alive)
-        if params[:alive].to_i == 0
+        if params[:alive].to_i.zero?
           render json: warriors.dead
         else
           render json: warriors.alive
diff --git a/lecture_4/homework/app/controllers/errors_controller.rb b/lecture_4/homework/app/controllers/errors_controller.rb
new file mode 100644
index 00000000..30458903
--- /dev/null
+++ b/lecture_4/homework/app/controllers/errors_controller.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class ErrorsController < ApplicationController
+  def index
+    raise Exceptions::SpecificError.new(extra: { date: DateTime.now, another_important_key: 4 })
+  end
+end
diff --git a/lecture_4/homework/config/application.rb b/lecture_4/homework/config/application.rb
index 02acf880..77549df4 100644
--- a/lecture_4/homework/config/application.rb
+++ b/lecture_4/homework/config/application.rb
@@ -33,5 +33,6 @@ class Application < Rails::Application
     # Middleware like session, flash, cookies can be added back manually.
     # Skip views, helpers and assets when generating a new resource.
     config.api_only = true
+    config.autoload_paths << Rails.root.join('lib/exceptions')
   end
 end
diff --git a/lecture_4/homework/config/initializers/sentry.rb b/lecture_4/homework/config/initializers/sentry.rb
new file mode 100644
index 00000000..d67d78fe
--- /dev/null
+++ b/lecture_4/homework/config/initializers/sentry.rb
@@ -0,0 +1,4 @@
+Raven.configure do |config|
+  config.dsn = 'https://774c7dbdb0304995af09d6b633d6c371:2fecc80d42a9418aa3268723022f5503@sentry.io/1433184'
+  config.sanitize_fields = Rails.application.config.filter_parameters.map(&:to_s)
+end
diff --git a/lecture_4/homework/lib/exceptions/exceptions.rb b/lecture_4/homework/lib/exceptions/exceptions.rb
new file mode 100644
index 00000000..38aa7e0b
--- /dev/null
+++ b/lecture_4/homework/lib/exceptions/exceptions.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module Exceptions
+  class MyAppError < StandardError
+    def initialize(message, context = {})
+      super(message)
+      @context = context
+    end
+
+    def raven_context
+      @context
+    end
+  end
+
+  class SpecificError < MyAppError
+    def initialize(context = {})
+      super('Message for SpecificError', context)
+    end
+  end
+end
diff --git a/lecture_4/homework/test/controllers/errors_controller_test.rb b/lecture_4/homework/test/controllers/errors_controller_test.rb
new file mode 100644
index 00000000..f08e83fb
--- /dev/null
+++ b/lecture_4/homework/test/controllers/errors_controller_test.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ErrorsControllerTest < ActionDispatch::IntegrationTest
+  # test "the truth" do
+  #   assert true
+  # end
+end

From d9079e5129d7ba210b6784fdd9364dc51d1b5a92 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Tue, 9 Apr 2019 22:34:52 +0200
Subject: [PATCH 03/14] Add NullObject pattern to handle cases when no weapon
 or mercenary

---
 lecture_4/homework/app/models/warrior.rb          | 4 ++++
 lecture_4/homework/app/models/warriors/hussar.rb  | 6 ++++++
 lecture_4/homework/app/models/warriors/samurai.rb | 6 ++++++
 lecture_4/homework/app/nulls/no_mercenary.rb      | 7 +++++++
 lecture_4/homework/app/nulls/no_weapon.rb         | 7 +++++++
 5 files changed, 30 insertions(+)
 create mode 100644 lecture_4/homework/app/nulls/no_mercenary.rb
 create mode 100644 lecture_4/homework/app/nulls/no_weapon.rb

diff --git a/lecture_4/homework/app/models/warrior.rb b/lecture_4/homework/app/models/warrior.rb
index eacdc13f..7d698bfb 100644
--- a/lecture_4/homework/app/models/warrior.rb
+++ b/lecture_4/homework/app/models/warrior.rb
@@ -14,4 +14,8 @@ class Warrior < ApplicationRecord
 
   scope :alive, -> { where('death_date IS NULL') }
   scope :dead, -> { where('death_date IS NOT NULL') }
+
+  def mercenary
+    super || NoMercenary.new.mercenary
+  end
 end
diff --git a/lecture_4/homework/app/models/warriors/hussar.rb b/lecture_4/homework/app/models/warriors/hussar.rb
index c277ff70..b8677d9b 100644
--- a/lecture_4/homework/app/models/warriors/hussar.rb
+++ b/lecture_4/homework/app/models/warriors/hussar.rb
@@ -5,6 +5,12 @@ class Hussar < Warrior
     attribute :preferred_weapon_kind, :string, default: :ranged
 
     def attack
+      weapon && attack_with_gun || NoWeapon.new.attack
+    end
+
+    private
+
+    def attack_with_gun
       "Hussar #{name} charged while yielding #{weapon.type.demodulize}"
     end
   end
diff --git a/lecture_4/homework/app/models/warriors/samurai.rb b/lecture_4/homework/app/models/warriors/samurai.rb
index 2b477760..6dabecba 100644
--- a/lecture_4/homework/app/models/warriors/samurai.rb
+++ b/lecture_4/homework/app/models/warriors/samurai.rb
@@ -5,6 +5,12 @@ class Samurai < Warrior
     attribute :preferred_weapon_kind, :string, default: :melee
 
     def attack
+      weapon && attack_with_gun || NoWeapon.new.attack
+    end
+
+    private
+
+    def attack_with_gun
       "Samurai #{name} attacked with #{weapon.type.demodulize}"
     end
   end
diff --git a/lecture_4/homework/app/nulls/no_mercenary.rb b/lecture_4/homework/app/nulls/no_mercenary.rb
new file mode 100644
index 00000000..c5d9d376
--- /dev/null
+++ b/lecture_4/homework/app/nulls/no_mercenary.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class NoMercenary
+  def mercenary
+    'This warrior has no mercenary'
+  end
+end
diff --git a/lecture_4/homework/app/nulls/no_weapon.rb b/lecture_4/homework/app/nulls/no_weapon.rb
new file mode 100644
index 00000000..f407fdb5
--- /dev/null
+++ b/lecture_4/homework/app/nulls/no_weapon.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class NoWeapon
+  def attack
+    'This warrior has no weapon'
+  end
+end

From a2e496d87274e473add17eeccd8db253741db332 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Tue, 9 Apr 2019 23:49:07 +0200
Subject: [PATCH 04/14] Create mercenaries method and available scope

---
 .../app/controllers/mercenaries_controller.rb   | 17 +++++++++++++----
 lecture_4/homework/app/models/mercenary.rb      |  1 +
 .../app/nulls/no_available_mercenary.rb         |  7 +++++++
 lecture_4/homework/app/nulls/no_mercenary.rb    |  2 +-
 4 files changed, 22 insertions(+), 5 deletions(-)
 create mode 100644 lecture_4/homework/app/nulls/no_available_mercenary.rb

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index 4382cfcf..58586eec 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -3,7 +3,7 @@
 # This controller is written badly on purpose. Please refactor this
 class MercenariesController < ApplicationController
   def index
-    render json: Mercenary.where('available_from < ?', Time.now).all
+    render json: mercenaries
   end
 
   def show
@@ -11,27 +11,36 @@ def show
   end
 
   def employ_best
-    mercenary = Mercenary.where('available_from < ?', Time.now).order(price: :asc).first # TODO: what about experience?
+    best_mercenary = mercenaries.available.order(experience: :desc).first
+    return unless best_mercenary
+
     clan = find_clan
     building = find_building
     warrior_class = clan.warriors.select('type, count(type) as warriors_count').group(:type).order('warriors_count ASC').first.class
-    warrior = warrior_class.create!(name: mercenary.name, clan: clan, building: building, preferred_weapon_kind: mercenary.preferred_weapon_kind, mercenary: mercenary)
-    create_good_weapon(mercenary)
+    warrior = warrior_class.create!(name: best_mercenary.name, clan: clan, building: building, preferred_weapon_kind: best_mercenary.preferred_weapon_kind, mercenary: best_mercenary)
+    create_good_weapon(best_mercenary)
+
     render json: warrior, include: [:mercenary], status: 201
   end
 
   def employ
     return unless mercenary.available_from < Time.now
+
     clan = find_clan
     building = find_building
     warrior_class = clan.warriors.select('type, count(type) as warriors_count').group(:type).order('warriors_count ASC').first.class
     warrior = warrior_class.create!(name: mercenary.name, clan: clan, building: building, preferred_weapon_kind: mercenary.preferred_weapon_kind, mercenary: mercenary)
     create_good_weapon(mercenary)
+
     render json: warrior, include: [:mercenary], status: 201
   end
 
   private
 
+  def mercenaries
+    @mercenaries ||= Mercenary.all
+  end
+
   def mercenary
     @mercenary ||= Mercenary.find(params[:id])
   end
diff --git a/lecture_4/homework/app/models/mercenary.rb b/lecture_4/homework/app/models/mercenary.rb
index 82aa4bdd..e9e61936 100644
--- a/lecture_4/homework/app/models/mercenary.rb
+++ b/lecture_4/homework/app/models/mercenary.rb
@@ -13,4 +13,5 @@ class Mercenary < ApplicationRecord
 
   scope :alive, -> { where('death_date IS NULL') }
   scope :dead, -> { where('death_date IS NOT NULL') }
+  scope :available, -> { where('available_from < ? AND warrior_id IS NULL', Time.now) }
 end
diff --git a/lecture_4/homework/app/nulls/no_available_mercenary.rb b/lecture_4/homework/app/nulls/no_available_mercenary.rb
new file mode 100644
index 00000000..af8ff4f9
--- /dev/null
+++ b/lecture_4/homework/app/nulls/no_available_mercenary.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class NoAvailableMercenary
+  def employ_best
+    'There is no available mercenary'
+  end
+end
diff --git a/lecture_4/homework/app/nulls/no_mercenary.rb b/lecture_4/homework/app/nulls/no_mercenary.rb
index c5d9d376..b1f32f6f 100644
--- a/lecture_4/homework/app/nulls/no_mercenary.rb
+++ b/lecture_4/homework/app/nulls/no_mercenary.rb
@@ -2,6 +2,6 @@
 
 class NoMercenary
   def mercenary
-    'This warrior has no mercenary'
+    "This warrrior doesn't have a mercenary"
   end
 end

From b6ff5af86ed16496fc621b039ed81953fe9c1b01 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Mon, 15 Apr 2019 11:36:27 +0200
Subject: [PATCH 05/14] Add Mercenary serializer

---
 .../homework/app/controllers/clans/warriors_controller.rb | 4 ++--
 .../homework/app/serializers/mercenary_serializer.rb      | 8 ++++++++
 lecture_4/homework/app/serializers/warrior_serializer.rb  | 1 +
 3 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 lecture_4/homework/app/serializers/mercenary_serializer.rb

diff --git a/lecture_4/homework/app/controllers/clans/warriors_controller.rb b/lecture_4/homework/app/controllers/clans/warriors_controller.rb
index acab2d6a..fc38b066 100644
--- a/lecture_4/homework/app/controllers/clans/warriors_controller.rb
+++ b/lecture_4/homework/app/controllers/clans/warriors_controller.rb
@@ -3,7 +3,7 @@
 module Clans
   class WarriorsController < ApplicationController
     def show
-      render json: warrior, include: %i[weapon building]
+      render json: warrior, include: %i[weapon building mercenary]
     end
 
     def index
@@ -16,7 +16,7 @@ def index
           render json: warriors.alive
         end
       else
-        render json: warriors
+        render json: warriors, include: [:mercenary]
       end
     end
 
diff --git a/lecture_4/homework/app/serializers/mercenary_serializer.rb b/lecture_4/homework/app/serializers/mercenary_serializer.rb
new file mode 100644
index 00000000..9cb4dad1
--- /dev/null
+++ b/lecture_4/homework/app/serializers/mercenary_serializer.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class MercenarySerializer < ActiveModel::Serializer
+  attributes :name, :experience, :preferred_weapon_kind, :available_from,
+             :warrior_id
+
+  belongs_to :warrior
+end
diff --git a/lecture_4/homework/app/serializers/warrior_serializer.rb b/lecture_4/homework/app/serializers/warrior_serializer.rb
index 2499bf85..00d73711 100644
--- a/lecture_4/homework/app/serializers/warrior_serializer.rb
+++ b/lecture_4/homework/app/serializers/warrior_serializer.rb
@@ -7,4 +7,5 @@ class WarriorSerializer < ActiveModel::Serializer
   belongs_to :clan
   belongs_to :building
   has_one :weapon
+  has_one :mercenary
 end

From 372efcd759534dd56f628dceea5c73014a5a7395 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Mon, 15 Apr 2019 12:21:14 +0200
Subject: [PATCH 06/14] Add MercenariesQueries

---
 .../app/controllers/mercenaries_controller.rb |  8 +++----
 .../homework/app/queries/mercenaries_query.rb | 22 +++++++++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)
 create mode 100644 lecture_4/homework/app/queries/mercenaries_query.rb

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index 58586eec..e4e55df7 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -11,7 +11,7 @@ def show
   end
 
   def employ_best
-    best_mercenary = mercenaries.available.order(experience: :desc).first
+    best_mercenary = MercenariesQuery.find_best
     return unless best_mercenary
 
     clan = find_clan
@@ -24,7 +24,7 @@ def employ_best
   end
 
   def employ
-    return unless mercenary.available_from < Time.now
+    return unless MercenariesQuery.can_be_hired(mercenary_id: mercenary.id)
 
     clan = find_clan
     building = find_building
@@ -38,11 +38,11 @@ def employ
   private
 
   def mercenaries
-    @mercenaries ||= Mercenary.all
+    @mercenaries ||= MercenariesQuery.all_mercenaries
   end
 
   def mercenary
-    @mercenary ||= Mercenary.find(params[:id])
+    @mercenary ||= MercenariesQuery.mercenary(mercenary_id: params[:id])
   end
 
   def find_building
diff --git a/lecture_4/homework/app/queries/mercenaries_query.rb b/lecture_4/homework/app/queries/mercenaries_query.rb
new file mode 100644
index 00000000..df3ec9dd
--- /dev/null
+++ b/lecture_4/homework/app/queries/mercenaries_query.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class MercenariesQuery
+  def self.can_be_hired(mercenary_id:, relation: Mercenary)
+    relation.find(mercenary_id).available_from < Time.now
+  end
+
+  def self.find_best(relation: Mercenary)
+    relation.all
+            .where('available_from < ? AND warrior_id IS NULL', Time.now)
+            .order(experience: :desc)
+            .first
+  end
+
+  def self.all_mercenaries(relation: Mercenary)
+    relation.all
+  end
+
+  def self.mercenary(mercenary_id:, relation: Mercenary)
+    relation.find(mercenary_id)
+  end
+end

From 2597a15d7341ad1056e2c8690da3749419ecb7e4 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Tue, 16 Apr 2019 07:31:59 +0200
Subject: [PATCH 07/14] Add more Mercenaries in db seeds

---
 lecture_4/homework/db/seeds.rb | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lecture_4/homework/db/seeds.rb b/lecture_4/homework/db/seeds.rb
index e3666e1a..5f6f7126 100644
--- a/lecture_4/homework/db/seeds.rb
+++ b/lecture_4/homework/db/seeds.rb
@@ -16,6 +16,9 @@
 unavailable_mercenary = Mercenary.create!(name: 'Cosimo Smallburrow', experience: 10, preferred_weapon_kind: 'melee', price: 100, available_from: 10.day.from_now)
 available_mercenary = Mercenary.create!(name: 'Priamus Brandagamba', experience: 5, preferred_weapon_kind: 'ranged', price: 20, available_from: 5.day.ago)
 expensive_mercenary = Mercenary.create!(name: 'Tanta Mugwort', experience: 50, preferred_weapon_kind: 'ranged', price: 200, available_from: 5.day.ago)
+expensive_mercenary_2 = Mercenary.create!(name: 'Moby Dick', experience: 60, preferred_weapon_kind: 'melee', price: 220, available_from: 6.day.ago)
+expensive_mercenary_3 = Mercenary.create!(name: 'Woody Allen', experience: 70, preferred_weapon_kind: 'ranged', price: 240, available_from: 7.day.ago)
+expensive_mercenary_4 = Mercenary.create!(name: 'Tony Hawk', experience: 80, preferred_weapon_kind: 'melee', price: 260, available_from: 8.day.ago)
 
 Weapons::Katana.create!(warrior: samurai_2, range: 3, damage: 30)
 Weapons::Katana.create!(warrior: samurai_3, range: 2, damage: 35)

From f063033a63c937ad0c6be811e0b0d30d6ca2ab8a Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Tue, 16 Apr 2019 08:13:58 +0200
Subject: [PATCH 08/14] Add Mercenaries, Clans and Buildings queries

---
 .../controllers/clans/warriors_controller.rb  | 12 +++---
 .../app/controllers/clans_controller.rb       |  6 +--
 .../app/controllers/mercenaries_controller.rb | 18 +++-----
 .../homework/app/queries/buildings_queries.rb |  7 ++++
 .../homework/app/queries/clans_queries.rb     | 19 +++++++++
 .../homework/app/queries/warriors_queries.rb  | 42 +++++++++++++++++++
 6 files changed, 83 insertions(+), 21 deletions(-)
 create mode 100644 lecture_4/homework/app/queries/buildings_queries.rb
 create mode 100644 lecture_4/homework/app/queries/clans_queries.rb
 create mode 100644 lecture_4/homework/app/queries/warriors_queries.rb

diff --git a/lecture_4/homework/app/controllers/clans/warriors_controller.rb b/lecture_4/homework/app/controllers/clans/warriors_controller.rb
index fc38b066..453ceda2 100644
--- a/lecture_4/homework/app/controllers/clans/warriors_controller.rb
+++ b/lecture_4/homework/app/controllers/clans/warriors_controller.rb
@@ -7,7 +7,7 @@ def show
     end
 
     def index
-      warriors = clan.warriors
+      warriors = WarriorsQueries.all_clans_warriors(clan: clan)
 
       if params.key?(:alive)
         if params[:alive].to_i.zero?
@@ -21,29 +21,29 @@ def index
     end
 
     def create
-      warrior = clan.warriors.create!(warrior_params)
+      warrior = WarriorsQueries.create_warrior(warrior_params: warrior_params, clan: clan)
 
       render json: warrior.to_json, include: %i[weapon building], status: 201
     end
 
     def update
-      warrior.update!(warrior_params)
+      WarriorsQueries.update_warrior(warrior: warrior, warrior_params: warrior_params)
 
       render json: warrior, include: %i[weapon building]
     end
 
     def destroy
-      warrior.destroy!
+      WarriorsQueries.destroy_warrior(warrior: warrior)
     end
 
     private
 
     def clan
-      @clan ||= Clan.find(params[:clan_id])
+      @clan ||= ClansQueries.find(clan_id: params[:clan_id])
     end
 
     def warrior
-      @warrior ||= clan.warriors.find(params[:id])
+      @warrior ||= WarriorsQueries.find_warrior(clan: clan, warrior_id: params[:id])
     end
 
     def warrior_params
diff --git a/lecture_4/homework/app/controllers/clans_controller.rb b/lecture_4/homework/app/controllers/clans_controller.rb
index 720823e0..3583645b 100644
--- a/lecture_4/homework/app/controllers/clans_controller.rb
+++ b/lecture_4/homework/app/controllers/clans_controller.rb
@@ -2,7 +2,7 @@
 
 class ClansController < ApplicationController
   def index
-    render json: Clan.all
+    render json: ClansQueries.all_clans
   end
 
   def show
@@ -10,7 +10,7 @@ def show
   end
 
   def create
-    clan = Clan.create!(clan_params)
+    clan = ClansQueries.create_clan(clan_params: clan_params)
 
     render json: clan, include: [:warriors], status: 201
   end
@@ -18,7 +18,7 @@ def create
   private
 
   def clan
-    @clan ||= Clan.find(params[:id])
+    @clan ||= ClansQueries.find(clan_id: params[:id])
   end
 
   def clan_params
diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index e4e55df7..211555e4 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -16,8 +16,8 @@ def employ_best
 
     clan = find_clan
     building = find_building
-    warrior_class = clan.warriors.select('type, count(type) as warriors_count').group(:type).order('warriors_count ASC').first.class
-    warrior = warrior_class.create!(name: best_mercenary.name, clan: clan, building: building, preferred_weapon_kind: best_mercenary.preferred_weapon_kind, mercenary: best_mercenary)
+    warrior_class = WarriorsQueries.choose_class(clan: clan)
+    warrior = WarriorsQueries.create_mercenary_warrior(warrior_class: warrior_class, mercenary: best_mercenary, clan: clan, building: building)
     create_good_weapon(best_mercenary)
 
     render json: warrior, include: [:mercenary], status: 201
@@ -28,8 +28,8 @@ def employ
 
     clan = find_clan
     building = find_building
-    warrior_class = clan.warriors.select('type, count(type) as warriors_count').group(:type).order('warriors_count ASC').first.class
-    warrior = warrior_class.create!(name: mercenary.name, clan: clan, building: building, preferred_weapon_kind: mercenary.preferred_weapon_kind, mercenary: mercenary)
+    warrior_class = WarriorsQueries.choose_class(clan: clan)
+    warrior = WarriorsQueries.create_mercenary_warrior(warrior_class: warrior_class, mercenary: mercenary, clan: clan, building: building)
     create_good_weapon(mercenary)
 
     render json: warrior, include: [:mercenary], status: 201
@@ -46,17 +46,11 @@ def mercenary
   end
 
   def find_building
-    if params[:building_id]
-      Building.find(params[:building_id])
-    end
+    BuildingsQueries.find_building(id: params[:building_id])
   end
 
   def find_clan
-    if params[:clan_id]
-      Clan.find(params[:clan_id])
-    else
-      Clan.order(warriors_count: :desc).first
-    end
+    ClansQueries.find(clan_id: params[:clan_id])
   end
 
   def create_good_weapon(mercenary)
diff --git a/lecture_4/homework/app/queries/buildings_queries.rb b/lecture_4/homework/app/queries/buildings_queries.rb
new file mode 100644
index 00000000..d9952dc6
--- /dev/null
+++ b/lecture_4/homework/app/queries/buildings_queries.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class BuildingsQueries
+  def self.find_building(id:, relation: Building)
+    relation.find(id) if id
+  end
+end
diff --git a/lecture_4/homework/app/queries/clans_queries.rb b/lecture_4/homework/app/queries/clans_queries.rb
new file mode 100644
index 00000000..f085031d
--- /dev/null
+++ b/lecture_4/homework/app/queries/clans_queries.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class ClansQueries
+  def self.find(clan_id:, relation: Clan)
+    if clan_id
+      relation.find(clan_id)
+    else
+      relation.order(warriors_count: :desc).first
+    end
+  end
+
+  def self.all_clans(relation: Clan)
+    relation.all
+  end
+
+  def self.create_clan(clan_params:, relation: Clan)
+    relation.create!(clan_params)
+  end
+end
diff --git a/lecture_4/homework/app/queries/warriors_queries.rb b/lecture_4/homework/app/queries/warriors_queries.rb
new file mode 100644
index 00000000..4e97dac4
--- /dev/null
+++ b/lecture_4/homework/app/queries/warriors_queries.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+class WarriorsQueries
+  def self.destroy_warrior(warrior:)
+    warrior.destroy!
+  end
+
+  def self.all_clans_warriors(clan:)
+    clan.warriors.all
+  end
+
+  def self.find_warrior(clan:, warrior_id:)
+    clan.warriors.find(warrior_id)
+  end
+
+  def self.create_warrior(clan:, warrior_params:)
+    clan.warriors.create!(warrior_params)
+  end
+
+  def self.update_warrior(warrior:, warrior_params:)
+    warrior.update!(warrior_params)
+  end
+
+  def self.choose_class(clan:)
+    clan.warriors
+        .select('type, count(type) as warriors_count')
+        .group(:type)
+        .order('warriors_count ASC')
+        .first
+        .class
+  end
+
+  def self.create_mercenary_warrior(warrior_class:, mercenary:, clan:, building:)
+    warrior_class.create!(
+      name: mercenary.name,
+      clan: clan,
+      building: building,
+      preferred_weapon_kind: mercenary.preferred_weapon_kind,
+      mercenary: mercenary
+    )
+  end
+end

From 8e33a3781bf6866aca5bd9a3d05f44ef049ed0f7 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Wed, 17 Apr 2019 12:16:17 +0200
Subject: [PATCH 09/14] Handle else case in create_good_weapon method

---
 .../app/controllers/mercenaries_controller.rb         |  2 +-
 lecture_4/homework/app/models/weapons/magic_wand.rb   | 11 +++++++++++
 lecture_4/homework/db/seeds.rb                        |  3 +++
 3 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 lecture_4/homework/app/models/weapons/magic_wand.rb

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index 211555e4..caa34f4e 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -60,7 +60,7 @@ def create_good_weapon(mercenary)
     when :ranged
       Weapons::Musket.create!(warrior: mercenary.warrior, range: 40, damage: 10)
     else
-      # TODO: some default?
+      Weapons::MagicWand.create!(warrior: mercenary.warrior, range: 20, damage: 45)
     end
   end
 end
diff --git a/lecture_4/homework/app/models/weapons/magic_wand.rb b/lecture_4/homework/app/models/weapons/magic_wand.rb
new file mode 100644
index 00000000..18d5b99c
--- /dev/null
+++ b/lecture_4/homework/app/models/weapons/magic_wand.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Weapons
+  class MagicWand < Weapon
+    attribute :kind, :string, default: :magical
+
+    def calculate_damage(distance)
+      distance < range ? damage * 3 : damage * 0.05
+    end
+  end
+end
diff --git a/lecture_4/homework/db/seeds.rb b/lecture_4/homework/db/seeds.rb
index 5f6f7126..c918e860 100644
--- a/lecture_4/homework/db/seeds.rb
+++ b/lecture_4/homework/db/seeds.rb
@@ -19,6 +19,9 @@
 expensive_mercenary_2 = Mercenary.create!(name: 'Moby Dick', experience: 60, preferred_weapon_kind: 'melee', price: 220, available_from: 6.day.ago)
 expensive_mercenary_3 = Mercenary.create!(name: 'Woody Allen', experience: 70, preferred_weapon_kind: 'ranged', price: 240, available_from: 7.day.ago)
 expensive_mercenary_4 = Mercenary.create!(name: 'Tony Hawk', experience: 80, preferred_weapon_kind: 'melee', price: 260, available_from: 8.day.ago)
+expensive_mercenary_5 = Mercenary.create!(name: 'Magic Man', experience: 100, preferred_weapon_kind: 'magical', price: 280, available_from: 8.day.ago)
+expensive_mercenary_6 = Mercenary.create!(name: 'Harry Potter', experience: 120, preferred_weapon_kind: 'magical', price: 300, available_from: 8.day.ago)
+expensive_mercenary_7 = Mercenary.create!(name: 'Bruce Magic Lee', experience: 140, preferred_weapon_kind: 'magical', price: 320, available_from: 8.day.ago)
 
 Weapons::Katana.create!(warrior: samurai_2, range: 3, damage: 30)
 Weapons::Katana.create!(warrior: samurai_3, range: 2, damage: 35)

From 08e1ee06ebe2b37babd44ded40ab3df75cf6459c Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Wed, 17 Apr 2019 12:18:13 +0200
Subject: [PATCH 10/14] Add object services, except create_good_weapon method

---
 .../app/controllers/mercenaries_controller.rb | 39 ++++-------
 lecture_4/homework/app/nulls/no_mercenary.rb  |  4 ++
 .../app/services/mercenary_recruiter.rb       | 66 +++++++++++++++++++
 3 files changed, 84 insertions(+), 25 deletions(-)
 create mode 100644 lecture_4/homework/app/services/mercenary_recruiter.rb

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index caa34f4e..f8e4a619 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -11,28 +11,25 @@ def show
   end
 
   def employ_best
-    best_mercenary = MercenariesQuery.find_best
-    return unless best_mercenary
+    mercenary = MercenariesQuery.find_best
 
-    clan = find_clan
-    building = find_building
-    warrior_class = WarriorsQueries.choose_class(clan: clan)
-    warrior = WarriorsQueries.create_mercenary_warrior(warrior_class: warrior_class, mercenary: best_mercenary, clan: clan, building: building)
-    create_good_weapon(best_mercenary)
+    render json: { error: NoMercenary.new.employ } and return unless mercenary
 
-    render json: warrior, include: [:mercenary], status: 201
+    MercenaryRecruiter.call(mercenary: mercenary, params: params)
+    create_good_weapon(mercenary: mercenary)
+
+    render json: mercenary, include: %i[warrior], status: 201
   end
 
   def employ
-    return unless MercenariesQuery.can_be_hired(mercenary_id: mercenary.id)
+    unless MercenariesQuery.can_be_hired(mercenary_id: mercenary.id)
+      render json: { error: NoMercenary.new.employ } and return
+    end
 
-    clan = find_clan
-    building = find_building
-    warrior_class = WarriorsQueries.choose_class(clan: clan)
-    warrior = WarriorsQueries.create_mercenary_warrior(warrior_class: warrior_class, mercenary: mercenary, clan: clan, building: building)
-    create_good_weapon(mercenary)
+    MercenaryRecruiter.call(mercenary: mercenary, params: params)
+    create_good_weapon(mercenary: mercenary)
 
-    render json: warrior, include: [:mercenary], status: 201
+    render json: mercenary, include: %i[warrior], status: 201
   end
 
   private
@@ -45,16 +42,8 @@ def mercenary
     @mercenary ||= MercenariesQuery.mercenary(mercenary_id: params[:id])
   end
 
-  def find_building
-    BuildingsQueries.find_building(id: params[:building_id])
-  end
-
-  def find_clan
-    ClansQueries.find(clan_id: params[:clan_id])
-  end
-
-  def create_good_weapon(mercenary)
-    case mercenary.preferred_weapon_kind
+  def create_good_weapon(mercenary:)
+    case mercenary.preferred_weapon_kind.to_sym
     when :melee
       Weapons::Katana.create!(warrior: mercenary.warrior, range: 2, damage: 25)
     when :ranged
diff --git a/lecture_4/homework/app/nulls/no_mercenary.rb b/lecture_4/homework/app/nulls/no_mercenary.rb
index b1f32f6f..cf3ede2f 100644
--- a/lecture_4/homework/app/nulls/no_mercenary.rb
+++ b/lecture_4/homework/app/nulls/no_mercenary.rb
@@ -4,4 +4,8 @@ class NoMercenary
   def mercenary
     "This warrrior doesn't have a mercenary"
   end
+
+  def employ
+    'There is no available mercenary'
+  end
 end
diff --git a/lecture_4/homework/app/services/mercenary_recruiter.rb b/lecture_4/homework/app/services/mercenary_recruiter.rb
new file mode 100644
index 00000000..bea0c631
--- /dev/null
+++ b/lecture_4/homework/app/services/mercenary_recruiter.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+class MercenaryRecruiter
+  def self.call(mercenary:, params:)
+    new(mercenary, params)
+  end
+
+  private
+
+  attr_reader :params, :mercenary
+
+  def initialize(mercenary, params)
+    @mercenary = mercenary
+    @params = params
+    employ
+  end
+
+  def employ
+    clan = ClanFinder.new(params: params[:clan_id]).call
+    building = BuildingFinder.new(params: params[:building_id]).call
+    warrior_class = WarriorsQueries.choose_class(clan: clan)
+
+    WarriorsQueries.create_mercenary_warrior(
+      warrior_class: warrior_class,
+      mercenary: mercenary,
+      clan: clan,
+      building: building
+    )
+  end
+end
+
+class ClanFinder
+  def initialize(params:)
+    @params = params
+  end
+
+  def call
+    find_clan
+  end
+
+  private
+
+  attr_reader :params
+
+  def find_clan
+    ClansQueries.find(clan_id: params)
+  end
+end
+
+class BuildingFinder
+  def initialize(params:)
+    @params = params
+  end
+
+  def call
+    find_building
+  end
+
+  private
+
+  attr_reader :params
+
+  def find_building
+    BuildingsQueries.find_building(id: params)
+  end
+end

From c9fee1144f03da1805ecb23aa7456a09f4267b8c Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Wed, 17 Apr 2019 13:49:55 +0200
Subject: [PATCH 11/14] Extract create_good_weapon method into separate service
 class

---
 .../app/controllers/mercenaries_controller.rb | 16 ------------
 .../app/services/mercenary_recruiter.rb       | 26 +++++++++++++++++++
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index f8e4a619..c30ae752 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -12,12 +12,9 @@ def show
 
   def employ_best
     mercenary = MercenariesQuery.find_best
-
     render json: { error: NoMercenary.new.employ } and return unless mercenary
 
     MercenaryRecruiter.call(mercenary: mercenary, params: params)
-    create_good_weapon(mercenary: mercenary)
-
     render json: mercenary, include: %i[warrior], status: 201
   end
 
@@ -27,8 +24,6 @@ def employ
     end
 
     MercenaryRecruiter.call(mercenary: mercenary, params: params)
-    create_good_weapon(mercenary: mercenary)
-
     render json: mercenary, include: %i[warrior], status: 201
   end
 
@@ -41,15 +36,4 @@ def mercenaries
   def mercenary
     @mercenary ||= MercenariesQuery.mercenary(mercenary_id: params[:id])
   end
-
-  def create_good_weapon(mercenary:)
-    case mercenary.preferred_weapon_kind.to_sym
-    when :melee
-      Weapons::Katana.create!(warrior: mercenary.warrior, range: 2, damage: 25)
-    when :ranged
-      Weapons::Musket.create!(warrior: mercenary.warrior, range: 40, damage: 10)
-    else
-      Weapons::MagicWand.create!(warrior: mercenary.warrior, range: 20, damage: 45)
-    end
-  end
 end
diff --git a/lecture_4/homework/app/services/mercenary_recruiter.rb b/lecture_4/homework/app/services/mercenary_recruiter.rb
index bea0c631..c055b163 100644
--- a/lecture_4/homework/app/services/mercenary_recruiter.rb
+++ b/lecture_4/homework/app/services/mercenary_recruiter.rb
@@ -26,6 +26,7 @@ def employ
       clan: clan,
       building: building
     )
+    WeaponCreator.new(mercenary: mercenary).call
   end
 end
 
@@ -64,3 +65,28 @@ def find_building
     BuildingsQueries.find_building(id: params)
   end
 end
+
+class WeaponCreator
+  def initialize(mercenary:)
+    @mercenary = mercenary
+  end
+
+  def call
+    create_good_weapon
+  end
+
+  private
+
+  attr_reader :mercenary
+
+  def create_good_weapon
+    case mercenary.preferred_weapon_kind.to_sym
+    when :melee
+      Weapons::Katana.create!(warrior: mercenary.warrior, range: 2, damage: 25)
+    when :ranged
+      Weapons::Musket.create!(warrior: mercenary.warrior, range: 40, damage: 10)
+    else
+      Weapons::MagicWand.create!(warrior: mercenary.warrior, range: 20, damage: 45)
+    end
+  end
+end

From fde8550ce1866da911042e492c852c233ad7e8c8 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Wed, 17 Apr 2019 13:55:31 +0200
Subject: [PATCH 12/14] Extract services into separate files

---
 .../app/controllers/mercenaries_controller.rb |  1 -
 .../homework/app/services/building_finder.rb  | 19 ++++++
 .../homework/app/services/clan_finder.rb      | 19 ++++++
 .../app/services/mercenary_recruiter.rb       | 61 -------------------
 .../homework/app/services/weapon_creator.rb   | 26 ++++++++
 5 files changed, 64 insertions(+), 62 deletions(-)
 create mode 100644 lecture_4/homework/app/services/building_finder.rb
 create mode 100644 lecture_4/homework/app/services/clan_finder.rb
 create mode 100644 lecture_4/homework/app/services/weapon_creator.rb

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index c30ae752..23078088 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 
-# This controller is written badly on purpose. Please refactor this
 class MercenariesController < ApplicationController
   def index
     render json: mercenaries
diff --git a/lecture_4/homework/app/services/building_finder.rb b/lecture_4/homework/app/services/building_finder.rb
new file mode 100644
index 00000000..edde9b07
--- /dev/null
+++ b/lecture_4/homework/app/services/building_finder.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class BuildingFinder
+  def initialize(params:)
+    @params = params
+  end
+
+  def call
+    find_building
+  end
+
+  private
+
+  attr_reader :params
+
+  def find_building
+    BuildingsQueries.find_building(id: params)
+  end
+end
diff --git a/lecture_4/homework/app/services/clan_finder.rb b/lecture_4/homework/app/services/clan_finder.rb
new file mode 100644
index 00000000..72c630c6
--- /dev/null
+++ b/lecture_4/homework/app/services/clan_finder.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class ClanFinder
+  def initialize(params:)
+    @params = params
+  end
+
+  def call
+    find_clan
+  end
+
+  private
+
+  attr_reader :params
+
+  def find_clan
+    ClansQueries.find(clan_id: params)
+  end
+end
diff --git a/lecture_4/homework/app/services/mercenary_recruiter.rb b/lecture_4/homework/app/services/mercenary_recruiter.rb
index c055b163..3f26251a 100644
--- a/lecture_4/homework/app/services/mercenary_recruiter.rb
+++ b/lecture_4/homework/app/services/mercenary_recruiter.rb
@@ -29,64 +29,3 @@ def employ
     WeaponCreator.new(mercenary: mercenary).call
   end
 end
-
-class ClanFinder
-  def initialize(params:)
-    @params = params
-  end
-
-  def call
-    find_clan
-  end
-
-  private
-
-  attr_reader :params
-
-  def find_clan
-    ClansQueries.find(clan_id: params)
-  end
-end
-
-class BuildingFinder
-  def initialize(params:)
-    @params = params
-  end
-
-  def call
-    find_building
-  end
-
-  private
-
-  attr_reader :params
-
-  def find_building
-    BuildingsQueries.find_building(id: params)
-  end
-end
-
-class WeaponCreator
-  def initialize(mercenary:)
-    @mercenary = mercenary
-  end
-
-  def call
-    create_good_weapon
-  end
-
-  private
-
-  attr_reader :mercenary
-
-  def create_good_weapon
-    case mercenary.preferred_weapon_kind.to_sym
-    when :melee
-      Weapons::Katana.create!(warrior: mercenary.warrior, range: 2, damage: 25)
-    when :ranged
-      Weapons::Musket.create!(warrior: mercenary.warrior, range: 40, damage: 10)
-    else
-      Weapons::MagicWand.create!(warrior: mercenary.warrior, range: 20, damage: 45)
-    end
-  end
-end
diff --git a/lecture_4/homework/app/services/weapon_creator.rb b/lecture_4/homework/app/services/weapon_creator.rb
new file mode 100644
index 00000000..d8fa50e4
--- /dev/null
+++ b/lecture_4/homework/app/services/weapon_creator.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+class WeaponCreator
+  def initialize(mercenary:)
+    @mercenary = mercenary
+  end
+
+  def call
+    create_good_weapon
+  end
+
+  private
+
+  attr_reader :mercenary
+
+  def create_good_weapon
+    case mercenary.preferred_weapon_kind.to_sym
+    when :melee
+      Weapons::Katana.create!(warrior: mercenary.warrior, range: 2, damage: 25)
+    when :ranged
+      Weapons::Musket.create!(warrior: mercenary.warrior, range: 40, damage: 10)
+    else
+      Weapons::MagicWand.create!(warrior: mercenary.warrior, range: 20, damage: 45)
+    end
+  end
+end

From 6f3caa05064cf8da57fb84caa2c0bee569919157 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Wed, 17 Apr 2019 14:06:24 +0200
Subject: [PATCH 13/14] Create WeaponsQueries

---
 lecture_4/homework/app/queries/weapons_queries.rb | 15 +++++++++++++++
 lecture_4/homework/app/services/weapon_creator.rb |  6 +++---
 2 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 lecture_4/homework/app/queries/weapons_queries.rb

diff --git a/lecture_4/homework/app/queries/weapons_queries.rb b/lecture_4/homework/app/queries/weapons_queries.rb
new file mode 100644
index 00000000..fadd79ca
--- /dev/null
+++ b/lecture_4/homework/app/queries/weapons_queries.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class WeaponsQueries
+  def self.create_katana(warrior:, relation:)
+    relation.create!(warrior: warrior, range: 2, damage: 25)
+  end
+
+  def self.create_musket(warrior:, relation:)
+    relation.create!(warrior: warrior, range: 40, damage: 10)
+  end
+
+  def self.create_magic_wand(warrior:, relation:)
+    relation.create!(warrior: warrior, range: 20, damage: 45)
+  end
+end
diff --git a/lecture_4/homework/app/services/weapon_creator.rb b/lecture_4/homework/app/services/weapon_creator.rb
index d8fa50e4..f1265107 100644
--- a/lecture_4/homework/app/services/weapon_creator.rb
+++ b/lecture_4/homework/app/services/weapon_creator.rb
@@ -16,11 +16,11 @@ def call
   def create_good_weapon
     case mercenary.preferred_weapon_kind.to_sym
     when :melee
-      Weapons::Katana.create!(warrior: mercenary.warrior, range: 2, damage: 25)
+      WeaponsQueries.create_katana(warrior: mercenary.warrior, relation: Weapons::Katana)
     when :ranged
-      Weapons::Musket.create!(warrior: mercenary.warrior, range: 40, damage: 10)
+      WeaponsQueries.create_musket(warrior: mercenary.warrior, relation: Weapons::Musket)
     else
-      Weapons::MagicWand.create!(warrior: mercenary.warrior, range: 20, damage: 45)
+      WeaponsQueries.create_magic_wand(warrior: mercenary.warrior, relation: Weapons::MagicWand)
     end
   end
 end

From 8bb38f6252d97bf4adbff1e744a0574b07ba65e1 Mon Sep 17 00:00:00 2001
From: Greg <wilusz.gregory@gmail.com>
Date: Wed, 17 Apr 2019 15:45:30 +0200
Subject: [PATCH 14/14] Refactor code - dry out code into separate methods

---
 .../app/controllers/mercenaries_controller.rb | 25 +++++++++++++------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/lecture_4/homework/app/controllers/mercenaries_controller.rb b/lecture_4/homework/app/controllers/mercenaries_controller.rb
index 23078088..6af36286 100644
--- a/lecture_4/homework/app/controllers/mercenaries_controller.rb
+++ b/lecture_4/homework/app/controllers/mercenaries_controller.rb
@@ -11,19 +11,15 @@ def show
 
   def employ_best
     mercenary = MercenariesQuery.find_best
-    render json: { error: NoMercenary.new.employ } and return unless mercenary
+    render_no_available_mercenary and return unless mercenary
 
-    MercenaryRecruiter.call(mercenary: mercenary, params: params)
-    render json: mercenary, include: %i[warrior], status: 201
+    recruit_mercenary(mercenary: mercenary)
   end
 
   def employ
-    unless MercenariesQuery.can_be_hired(mercenary_id: mercenary.id)
-      render json: { error: NoMercenary.new.employ } and return
-    end
+    render_no_available_mercenary and return unless can_be_hired?
 
-    MercenaryRecruiter.call(mercenary: mercenary, params: params)
-    render json: mercenary, include: %i[warrior], status: 201
+    recruit_mercenary(mercenary: mercenary)
   end
 
   private
@@ -35,4 +31,17 @@ def mercenaries
   def mercenary
     @mercenary ||= MercenariesQuery.mercenary(mercenary_id: params[:id])
   end
+
+  def recruit_mercenary(mercenary:)
+    MercenaryRecruiter.call(mercenary: mercenary, params: params)
+    render json: mercenary, include: %i[warrior], status: 201
+  end
+
+  def render_no_available_mercenary
+    render json: { error: NoMercenary.new.employ }
+  end
+
+  def can_be_hired?
+    MercenariesQuery.can_be_hired(mercenary_id: mercenary.id)
+  end
 end