Gemfile.lock

@@ -220,7 +220,7 @@ GEM
       racc (~> 1.4)
     orm_adapter (0.5.0)
     parallel (1.26.3)
-    parser (3.3.7.0)
+    parser (3.3.6.0)
       ast (~> 2.4.1)
       racc
     pg (1.5.9)
@@ -343,12 +343,12 @@ GEM
       parser (>= 3.3.1.0)
     rubocop-factory_bot (2.26.1)
       rubocop (~> 1.61)
-    rubocop-rails (2.29.0)
+    rubocop-rails (2.28.0)
       activesupport (>= 4.2.0)
       rack (>= 1.1)
       rubocop (>= 1.52.0, < 2.0)
       rubocop-ast (>= 1.31.1, < 2.0)
-    rubocop-rspec (3.4.0)
+    rubocop-rspec (3.3.0)
       rubocop (~> 1.61)
     rubocop-rspec_rails (2.30.0)
       rubocop (~> 1.61)
@@ -541,7 +541,7 @@ CHECKSUMS
   nokogiri (1.18.1-x86_64-linux-gnu) sha256=e516cf16ccde67ed4cc595a2621ca5ddd42562ecb24928914b0045a20a41620e
   orm_adapter (0.5.0) sha256=aa5d0be5d540cbb46d3a93e88061f4ece6a25f6e97d6a47122beb84fe595e9b9
   parallel (1.26.3) sha256=d86babb7a2b814be9f4b81587bf0b6ce2da7d45969fab24d8ae4bf2bb4d4c7ef
-  parser (3.3.7.0) sha256=7449011771e3e7881297859b849de26a6f4fccd515bece9520a87e7d2116119b
+  parser (3.3.6.0) sha256=25d4e67cc4f0f7cab9a2ae1f38e2005b6904d2ea13c34734511d0faad038bc3b
   pg (1.5.9) sha256=761efbdf73b66516f0c26fcbe6515dc7500c3f0aa1a1b853feae245433c64fdc
   pluck_to_hash (1.0.2) sha256=1599906239716f98262a41493dd7d4cb72e8d83ad3d76d666deacfc5de50a47e
   pry (0.15.2) sha256=12d54b8640d3fa29c9211dd4ffb08f3fd8bf7a4fd9b5a73ce5b59c8709385b6b
@@ -581,8 +581,8 @@ CHECKSUMS
   rubocop (1.70.0) sha256=96751f8440b36a0ac6e9a8ab596900803118d83d6b83f2037bf8b3d7a5bc440e
   rubocop-ast (1.37.0) sha256=9513ac88aaf113d04b52912533ffe46475de1362d4aa41141b51b2455827c080
   rubocop-factory_bot (2.26.1) sha256=8de13cd4edcee5ca800f255188167ecef8dbfc3d1fae9f15734e9d2e755392aa
-  rubocop-rails (2.29.0) sha256=35bffd140c80671453aafac0e2d5ab5b3dd65736a3fc8f3936ccca226b89c234
+  rubocop-rails (2.28.0) sha256=4967bed9ea13e6dcab566fea4265a6dd0381db739b305e48930aba1282da2715
-  rubocop-rspec (3.4.0) sha256=8721c13b6a8c9530a7ac481cea9423022f946fcf72428bda8289f8b57e4d4885
+  rubocop-rspec (3.3.0) sha256=79e1b281a689044d1516fefbc52e2e6c06cd367c25ebeaf06a7a198e9071cd7d
   rubocop-rspec_rails (2.30.0) sha256=888112e83f9d7ef7ad2397e9d69a0b9614a4bae24f072c399804a180f80c4c46
   ruby-progressbar (1.13.0) sha256=80fc9c47a9b640d6834e0dc7b3c94c9df37f08cb072b7761e4a71e22cff29b33
   rubytree (2.1.1) sha256=4925016356a81730e982f1f8c3b5f8da461f18906c77d238bad4c4ba896abd41

app/controllers/affinities_controller.rb

@@ -26,7 +26,7 @@ class AffinitiesController < ApplicationController
       }
     end
 
-    GroupAffinity.upsert_all(affinities, unique_by: :uindex_group_pair)
+    GroupAffinity.upsert_all(affinities)
 
     render json: {}, status: :ok
   rescue ActiveRecord::InvalidForeignKey
@@ -36,25 +36,21 @@ class AffinitiesController < ApplicationController
   end
 
   def default
-    hierarchy = AffinityGroupsHierarchy.new
-
     for_each_group do |group_id|
-      hierarchy.default_discomfort(@group.id, group_id).to_f
+      Tables::DiscomfortCalculator.cohesion_discomfort(id_a: @group.id, id_b: group_id).to_f
     end
   end
 
   def reset
-    hierarchy = AffinityGroupsHierarchy.new
-
     affinities = Group.pluck(:id).combination(2).map do |(group_a_id, group_b_id)|
       {
         group_a_id:,
         group_b_id:,
-        discomfort: hierarchy.default_discomfort(group_a_id, group_b_id).to_f
+        discomfort: Tables::DiscomfortCalculator.cohesion_discomfort(id_a: group_a_id, id_b: group_b_id).to_f
       }
     end
 
-    GroupAffinity.upsert_all(affinities, unique_by: :uindex_group_pair)
+    GroupAffinity.upsert_all(affinities)
 
     render json: {}, status: :ok
   end

app/controllers/expenses_controller.rb

@@ -31,6 +31,6 @@ class ExpensesController < ApplicationController
   private
 
   def expense_params
-    params.expect(expense: %i[name amount pricing_type])
+    params.require(:expense).permit(:name, :amount, :pricing_type)
   end
 end

app/controllers/guests_controller.rb

@@ -32,6 +32,6 @@ class GuestsController < ApplicationController
   private
 
   def guest_params
-    params.expect(guest: %i[name group_id status])
+    params.require(:guest).permit(:name, :group_id, :status)
   end
 end

app/services/affinity_groups_hierarchy.rb

@@ -5,7 +5,7 @@
 # frozen_string_literal: true
 
 class AffinityGroupsHierarchy < Array
-  DEFAULT_DISCOMFORT = 1
+  include Singleton
 
   def initialize
     super
@@ -16,9 +16,6 @@ class AffinityGroupsHierarchy < Array
 
       hydrate(group)
     end
-
-    load_discomforts
-    freeze
   end
 
   def find(id)
@@ -40,35 +37,8 @@ class AffinityGroupsHierarchy < Array
     @references[id_a].distance_to_common_ancestor(@references[id_b])
   end
 
-  def discomfort(id_a, id_b)
-    return 0 if id_a == id_b
-
-    @discomforts[uuid_to_int(id_a) + uuid_to_int(id_b)] || DEFAULT_DISCOMFORT
-  end
-
-  def default_discomfort(id_a, id_b)
-    return 0 if id_a == id_b
-
-    dist = distance(id_a, id_b)
-
-    return DEFAULT_DISCOMFORT if dist.nil?
-
-    Rational(dist, dist + 1)
-  end
-
   private
 
-  def load_discomforts
-    @load_discomforts ||= GroupAffinity.pluck(:group_a_id, :group_b_id,
-                                              :discomfort).each_with_object({}) do |(id_a, id_b, discomfort), acc|
-      acc[uuid_to_int(id_a) + uuid_to_int(id_b)] = discomfort
-    end
-  end
-
-  def uuid_to_int(uuid)
-    uuid.gsub('-', '').hex
-  end
-
   def hydrate(group)
     group.children.each do |child|
       register_child(group.id, child.id)

app/services/tables/discomfort_calculator.rb

@@ -6,10 +6,19 @@
 
 module Tables
   class DiscomfortCalculator
-    private attr_reader :table, :hierarchy
+    class << self
-    def initialize(table:, hierarchy: AffinityGroupsHierarchy.new)
+      def cohesion_discomfort(id_a:, id_b:)
+        distance = AffinityGroupsHierarchy.instance.distance(id_a, id_b)
+
+        return 1 if distance.nil?
+
+        Rational(distance, distance + 1)
+      end
+    end
+
+    private attr_reader :table
+    def initialize(table:)
       @table = table
-      @hierarchy = hierarchy
     end
 
     def calculate
@@ -50,7 +59,7 @@ module Tables
     #
     def cohesion_discomfort
       table.map(&:group_id).tally.to_a.combination(2).sum do |(a, count_a), (b, count_b)|
-        count_a * count_b * hierarchy.discomfort(a, b)
+        count_a * count_b * self.class.cohesion_discomfort(id_a: a, id_b: b)
       end
     end
   end

app/services/tables/distribution.rb

@@ -13,7 +13,6 @@ module Tables
     def initialize(min_per_table:, max_per_table:)
       @min_per_table = min_per_table
       @max_per_table = max_per_table
-      @hierarchy = AffinityGroupsHierarchy.new
       @tables = []
     end
 
@@ -36,6 +35,12 @@ module Tables
       "#{@tables.count} tables, discomfort: #{discomfort}"
     end
 
+    def pretty_print
+      @tables.map.with_index do |table, i|
+        "Table #{i + 1} (#{table.count} ppl): (#{local_discomfort(table)}) #{table.map(&:name).join(', ')}"
+      end.join("\n")
+    end
+
     def deep_dup
       self.class.new(min_per_table: @min_per_table, max_per_table: @max_per_table).tap do |new_distribution|
         new_distribution.tables = @tables.map(&:dup)
@@ -63,7 +68,7 @@ module Tables
     private
 
     def local_discomfort(table)
-      table.discomfort ||= DiscomfortCalculator.new(table:, hierarchy:).calculate
+      table.discomfort ||= DiscomfortCalculator.new(table:).calculate
     end
   end
 end

spec/services/tables/discomfort_calculator_spec.rb

@@ -75,5 +75,159 @@ module Tables
         it { expect(calculator.send(:table_size_penalty)).to eq(10) }
       end
     end
+
+    describe '#cohesion_discomfort' do
+      before do
+        # Overridden in each test except trivial cases
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).and_call_original
+
+        %w[family friends work school].each do |group|
+          allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(group, group).and_return(0)
+        end
+
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(family.id, friends.id).and_return(nil)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(friends.id, work.id).and_return(1)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(family.id, work.id).and_return(2)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(family.id, school.id).and_return(3)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(friends.id, school.id).and_return(4)
+        allow(AffinityGroupsHierarchy.instance).to receive(:distance).with(work.id, school.id).and_return(5)
+      end
+
+      context 'when the table contains just two guests' do
+        context 'when they belong to the same group' do
+          let(:table) { create_list(:guest, 2, group: family) }
+
+          it { expect(calculator.send(:cohesion_discomfort)).to eq(0) }
+        end
+
+        context 'when they belong to completely unrelated groups' do
+          let(:table) do
+            [
+              create(:guest, group: family),
+              create(:guest, group: friends)
+            ]
+          end
+
+          it { expect(calculator.send(:cohesion_discomfort)).to eq(1) }
+        end
+
+        context 'when they belong to groups at a distance of 1' do
+          let(:table) do
+            [
+              create(:guest, group: friends),
+              create(:guest, group: work)
+            ]
+          end
+
+          it { expect(calculator.send(:cohesion_discomfort)).to eq(0.5) }
+        end
+
+        context 'when they belong to groups at a distance of 2' do
+          let(:table) do
+            [
+              create(:guest, group: family),
+              create(:guest, group: work)
+            ]
+          end
+
+          it { expect(calculator.send(:cohesion_discomfort)).to eq(Rational(2, 3)) }
+        end
+
+        context 'when they belong to groups at a distance of 3' do
+          let(:table) do
+            [
+              create(:guest, group: family),
+              create(:guest, group: school)
+            ]
+          end
+
+          it { expect(calculator.send(:cohesion_discomfort)).to eq(Rational(3, 4)) }
+        end
+      end
+
+      context 'when the table contains three guests' do
+        let(:table) do
+          [
+            create(:guest, group: family),
+            create(:guest, group: friends),
+            create(:guest, group: work)
+          ]
+        end
+
+        it 'returns the sum of the penalties for each pair of guests' do
+          expect(calculator.send(:cohesion_discomfort)).to eq(1 + Rational(1, 2) + Rational(2, 3))
+        end
+      end
+
+      context 'when the table contains four guests of different groups' do
+        let(:table) do
+          [
+            create(:guest, group: family),
+            create(:guest, group: friends),
+            create(:guest, group: work),
+            create(:guest, group: school)
+          ]
+        end
+
+        it 'returns the sum of the penalties for each pair of guests' do
+          expect(calculator.send(:cohesion_discomfort))
+            .to eq(1 + Rational(1, 2) + Rational(2, 3) + Rational(3, 4) + Rational(4, 5) + Rational(5, 6))
+        end
+      end
+
+      context 'when the table contains four guests of two evenly split groups' do
+        let(:table) do
+          [
+            create_list(:guest, 2, group: family),
+            create_list(:guest, 2, group: friends)
+          ].flatten
+        end
+
+        it 'returns the sum of the penalties for each pair of guests' do
+          expect(calculator.send(:cohesion_discomfort)).to eq(4)
+        end
+      end
+
+      context 'when the table contains six guests of two unevenly split groups' do
+        let(:table) do
+          [
+            create_list(:guest, 2, group: family),
+            create_list(:guest, 4, group: friends)
+          ].flatten
+        end
+
+        it 'returns the sum of the penalties for each pair of guests' do
+          expect(calculator.send(:cohesion_discomfort)).to eq(8)
+        end
+      end
+
+      context 'when the table contains six guests of three evenly split groups' do
+        let(:table) do
+          [
+            create_list(:guest, 2, group: family),
+            create_list(:guest, 2, group: friends),
+            create_list(:guest, 2, group: work)
+          ].flatten
+        end
+
+        it 'returns the sum of the penalties for each pair of guests' do
+          expect(calculator.send(:cohesion_discomfort)).to eq((4 * 1) + (4 * Rational(1, 2)) + (4 * Rational(2, 3)))
+        end
+      end
+
+      context 'when the table contains six guests of three unevenly split groups' do
+        let(:table) do
+          [
+            create_list(:guest, 3, group: family),
+            create_list(:guest, 2, group: friends),
+            create_list(:guest, 1, group: work)
+          ].flatten
+        end
+
+        it 'returns the sum of the penalties for each pair of guests' do
+          expect(calculator.send(:cohesion_discomfort)).to eq((6 * 1) + (2 * Rational(1, 2)) + (3 * Rational(2, 3)))
+        end
+      end
+    end
   end
 end