Merge pull request #674 from alphagov/add-petition-statistics

Add statistics about duplicate email usage

Author: pixeltrix

Gemfile

@@ -58,6 +58,7 @@ group :test do
   gem 'email_spec'
   gem 'launchy'
   gem 'webmock'
+  gem 'test_after_commit'
 end
 
 group :production do

Gemfile.lock

@@ -278,6 +278,8 @@ GEM
       sprockets (>= 3.0.0)
     terrapin (0.6.0)
       climate_control (>= 0.0.3, < 1.0)
+    test_after_commit (1.2.2)
+      activerecord (>= 3.2, < 5.0)
     textacular (3.2.2)
       activerecord (>= 3.0, < 5.0)
     thor (0.20.3)
@@ -349,6 +351,7 @@ DEPENDENCIES
   sass-rails (~> 5.0)
   shoulda-matchers
   slack-notifier
+  test_after_commit
   textacular
   uglifier
   webmock

app/assets/stylesheets/petitions/admin/_meta.scss

@@ -13,6 +13,15 @@
         }
       }
     }
+
+    .statistics-meta {
+      small {
+        @include core-14;
+        color: $grey-1;
+        display: block;
+        margin-bottom: em(6, 16);
+      }
+    }
   }
 
   .petition-meta-state, .petition-meta-signature-count {

app/controllers/admin/petition_statistics_controller.rb

@@ -0,0 +1,15 @@
+class Admin::PetitionStatisticsController < Admin::AdminController
+  before_action :require_sysadmin
+  before_action :fetch_petition
+
+  def update
+    UpdatePetitionStatisticsJob.perform_later(@petition)
+    redirect_to admin_petition_url(@petition), notice: :enqueued_petition_statistics_update
+  end
+
+  private
+
+  def fetch_petition
+    @petition = Petition.moderated.find(params[:petition_id])
+  end
+end

app/jobs/enqueue_petition_statistics_updates_job.rb

@@ -0,0 +1,9 @@
+class EnqueuePetitionStatisticsUpdatesJob < ApplicationJob
+  queue_as :low_priority
+
+  def perform(timestamp)
+    Petition.signed_since(timestamp.in_time_zone).find_each do |petition|
+      UpdatePetitionStatisticsJob.perform_later(petition)
+    end
+  end
+end

app/jobs/update_petition_statistics_job.rb

@@ -0,0 +1,7 @@
+class UpdatePetitionStatisticsJob < ApplicationJob
+  queue_as :low_priority
+
+  def perform(petition)
+    petition.statistics.refresh!
+  end
+end

app/models/petition.rb

@@ -76,6 +76,7 @@ class Petition < ActiveRecord::Base
   has_one :government_response, dependent: :destroy
   has_one :note, dependent: :destroy
   has_one :rejection, dependent: :destroy
+  has_one :statistics, dependent: :destroy
 
   has_many :signatures
   has_many :sponsors, -> { sponsors }, class_name: 'Signature'
@@ -383,6 +384,10 @@ def untagged_in_moderation
       untagged.in_moderation
     end
 
+    def signed_since(timestamp)
+      where(arel_table[:last_signed_at].gt(timestamp))
+    end
+
     private
 
     def moderation_threshold_reached_at
@@ -429,6 +434,10 @@ def scheduled_debate_state
     end
   end
 
+  def statistics
+    super || create_statistics!
+  end
+
   def update_signature_count!
     sql = "signature_count = (?), updated_at = ?"
     count = Signature.arel_table[Arel.star].count

app/models/petition/statistics.rb

@@ -0,0 +1,26 @@
+class Petition < ActiveRecord::Base
+  class Statistics < ActiveRecord::Base
+    belongs_to :petition
+
+    after_commit on: :create do
+      UpdatePetitionStatisticsJob.perform_later(petition)
+    end
+
+    def refresh!(now = Time.current)
+      update!(
+        refreshed_at: now,
+        duplicate_emails: refresh_duplicate_emails
+      )
+    end
+
+    def refreshed?
+      refreshed_at?
+    end
+
+    private
+
+      def refresh_duplicate_emails
+        petition.signatures.duplicate_emails
+      end
+  end
+end

app/models/signature.rb

@@ -90,6 +90,10 @@ def duplicate(id, email)
       where(arel_table[:id].not_eq(id).and(arel_table[:email].eq(email)))
     end
 
+    def duplicate_emails
+      unscoped.from(validated.select(:uuid).group(:uuid).having(arel_table[Arel.star].count.gt(1))).count
+    end
+
     def for_email(email)
       where(email: email.downcase)
     end

app/views/admin/petitions/_petition_details.html.erb

@@ -37,6 +37,11 @@
   <% end %>
 
   <% if current_user.is_a_sysadmin? %>
+    <% if @petition.statistics.refreshed? %>
+      <dt>Duplicate emails</dt>
+      <dd><%= number_with_delimiter(@petition.statistics.duplicate_emails) %></dd>
+    <% end %>
+
     <% if @petition.fraudulent_domains? %>
       <dt>Fraudulent domains</dt>
       <dd>
@@ -53,3 +58,17 @@
   <% end %>
 <% end %>
 </dl>
+
+<% if current_user.is_a_sysadmin? %>
+  <div class="statistics-meta">
+    <small>
+      <% if @petition.statistics.refreshed? %>
+        Statistics last updated at <time datetime="<%= @petition.statistics.refreshed_at.iso8601 %>"><%= date_time_format(@petition.statistics.refreshed_at) %></time>
+      <% else %>
+        Statistics not yet generated
+      <% end %>
+    </small>
+
+    <%=  button_to 'Refresh', admin_petition_statistics_url(@petition), method: :patch, class: 'button' %>
+  </div>
+<% end %>