Functions Recommendations

src/app/helpers/recommendations_helper.rb

@@ -0,0 +1,66 @@
+module RecommendationsHelper
+  MAX_RECOMMENDED_FUNCTIONS = 5
+
+  module RecommendationsPartialPath
+    def to_partial_path
+      'recommendations/function'
+    end
+  end
+
+  def more_from_user_function(function)
+    most_liked = user_most_function function.user, likes_count: :desc
+    most_commented = user_most_function function.user, comments_count: :desc
+    most_saved = user_most_function function.user, saves_count: :desc
+
+    recommended_functions = filter_unwanted [most_liked, most_commented, most_saved], function
+    override_partial_path recommended_functions, RecommendationsPartialPath
+  end
+
+  def similar_functions(function)
+    popularity_query = generate_popularity_query
+
+    popular_functions_from_tags = function.tags.map { |tag| tag.functions.order(popularity_query).first }
+    popular_functions = Function.order(Arel.sql(popularity_query))
+                                .limit(MAX_RECOMMENDED_FUNCTIONS - popular_functions_from_tags.count)
+
+    recommended_functions = filter_unwanted [*popular_functions_from_tags, *popular_functions], function
+    override_partial_path recommended_functions, RecommendationsPartialPath
+  end
+
+  private
+
+  def override_partial_path(functions, partial_path_module)
+    functions.map { |obj| obj.extend(partial_path_module) }
+  end
+
+  def generate_popularity_query
+    likes_wieght = 1
+    comments_weight = 0.5
+    saves_weight = 0.25
+
+    "( (likes_count * #{likes_wieght}) + (comments_count * #{comments_weight}) + (saves_count * #{saves_weight}) ) desc"
+  end
+
+  # Returns the most x function for a certain user
+  # based on a criteria defined in `parameter`.
+  #
+  # @param user [User]
+  # @param parameter [Hash]
+  # @returns [Function]
+  def user_most_function(user, parameter)
+    user.functions.order(parameter).first
+  end
+
+  # Filters an array of Functions. It removes an `unwated_function`
+  # and any `nil` variables in the `functions` array.
+  #
+  # @param functions [Array<Function>]
+  #
+  # @param unwanted_functon [Function] a function to be filtered
+  # out of the Functions array.
+  #
+  # @returns [Array<Function>]
+  def filter_unwanted(functions, unwanted_function)
+    functions.reject { |func| func.nil? || func == unwanted_function }.uniq
+  end
+end

src/app/views/functions/show.html.erb

@@ -1,5 +1,13 @@
 <%= content_for :title, sprintf("%s - by: %s", @function.name, @user.name) %>
-<%= render 'tags/tags', tags: @function.tags %>
-<%= render @function, full: true %>
-<%= render @function.comments %>
-<%= render 'comments/form', comment: @comment if can?(@comment, :create) %>
+
+<div class="columns">
+  <div class="column is-four-fifths">
+    <%= render 'tags/tags', tags: @function.tags %>
+    <%= render @function, full: true %>
+    <%= render @function.comments %>
+    <%= render 'comments/form', comment: @comment if can?(@comment, :create) %>
+  </div>
+  <div class="column">
+    <%= render 'recommendations/recommendations', function: @function %>
+  </div>
+</div>

src/app/views/recommendations/_function.html.erb

@@ -0,0 +1 @@
+<%= link_to "#{function.user.username}/#{function.name}", [function.user, function], class: 'panel-block' %>

src/app/views/recommendations/_recommendation.html.erb

@@ -0,0 +1,10 @@
+<% unless functions.empty? %>
+
+  <article class="panel has-background-white">
+    <p class="panel-heading">
+      <%= recommendation_title %>
+    </p>
+    <%= render functions %>
+  </article>
+
+<% end %>

src/app/views/recommendations/_recommendations.html.erb

@@ -0,0 +1,2 @@
+<%= render 'recommendations/recommendation', recommendation_title: 'Similar Functions', functions: similar_functions(function) %>
+<%= render 'recommendations/recommendation', recommendation_title: "More from #{function.user.name}", functions: more_from_user_function(function) %>

src/spec/helpers/recommendations_helper_spec.rb

@@ -0,0 +1,14 @@
+require 'rails_helper'
+
+RSpec.describe RecommendationsHelper do
+  let!(:users) { create_list(:user, 5) }
+  let(:functions) { users.map { |user| create_list(:function, 5, user: user) }.flatten }
+
+  describe '#more_from_user_function' do
+    it { expect(helper.more_from_user_function(functions.sample)).to include(a_kind_of(Function)) }
+  end
+
+  describe '#similar_functions' do
+    it { expect(helper.similar_functions(functions.sample)).to include(a_kind_of(Function)) }
+  end
+end