Add user cohorts table to admin area

app/assets/javascripts/dispatcher.js

@@ -366,6 +366,7 @@ const ShortcutsBlob = require('./shortcuts_blob');
           new Admin();
           switch (path[1]) {
             case 'application_settings':
+            case 'user_cohorts':
               new gl.ApplicationSettings();
               break;
             case 'groups':

app/controllers/admin/application_settings_controller.rb

@@ -19,7 +19,12 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
 
   def usage_data
     respond_to do |format|
-      format.html { render html: Gitlab::Highlight.highlight('payload.json', Gitlab::UsageData.to_json) }
+      format.html do
+        usage_data = Gitlab::UsageData.data
+        usage_data_json = params[:pretty] ? JSON.pretty_generate(usage_data) : usage_data.to_json
+
+        render html: Gitlab::Highlight.highlight('payload.json', usage_data_json)
+      end
       format.json { render json: Gitlab::UsageData.to_json }
     end
   end

app/controllers/admin/user_cohorts_controller.rb

+class Admin::UserCohortsController < Admin::ApplicationController
+  def index
+    if ApplicationSetting.current.usage_ping_enabled
+      @cohorts = UserCohortsService.new.execute(12)
+    end
+  end
+end

app/services/user_cohorts_service.rb

+class UserCohortsService
+  def initialize
+  end
+
+  def execute(months_included)
+    if Gitlab::Database.postgresql?
+      created_at_month = "CAST(DATE_TRUNC('month', created_at) AS date)"
+      current_sign_in_at_month = "CAST(DATE_TRUNC('month', current_sign_in_at) AS date)"
+    elsif Gitlab::Database.mysql?
+      created_at_month = "STR_TO_DATE(DATE_FORMAT(created_at, '%Y-%m-01'), '%Y-%m-%d')"
+      current_sign_in_at_month = "STR_TO_DATE(DATE_FORMAT(current_sign_in_at, '%Y-%m-01'), '%Y-%m-%d')"
+    end
+
+    counts_by_month =
+      User
+        .where('created_at > ?', months_included.months.ago.end_of_month)
+        .group(created_at_month, current_sign_in_at_month)
+        .reorder("#{created_at_month} ASC", "#{current_sign_in_at_month} DESC")
+        .count
+
+    cohorts = {}
+    months = Array.new(months_included) { |i| i.months.ago.beginning_of_month.to_date }
+
+    months_included.times do
+      month = months.last
+      inactive = counts_by_month[[month, nil]] || 0
+
+      # Calculate a running sum of active users, so users active in later months
+      # count as active in this month, too. Start with the most recent month
+      # first, for calculating the running totals, and then reverse for
+      # displaying in the table.
+      activity_months =
+        months
+          .map { |activity_month| counts_by_month[[month, activity_month]] }
+          .reduce([]) { |result, total| result << result.last.to_i + total.to_i }
+          .reverse
+
+      cohorts[month] = {
+        months: activity_months,
+        total: activity_months.first,
+        inactive: inactive
+      }
+
+      months.pop
+    end
+
+    cohorts
+  end
+end

app/views/admin/application_settings/_form.html.haml

@@ -477,7 +477,7 @@
           diagrams in Asciidoc documents using an external PlantUML service.
 
   %fieldset
-    %legend Usage statistics
+    %legend#usage-statistics Usage statistics
     .form-group
       .col-sm-offset-2.col-sm-10
         .checkbox

app/views/admin/dashboard/_head.html.haml

@@ -27,3 +27,7 @@
           = link_to admin_runners_path, title: 'Runners' do
             %span
               Runners
+        = nav_link path: 'user_cohorts#index' do
+          = link_to admin_user_cohorts_path, title: 'User cohorts' do
+            %span
+              User cohorts

app/views/admin/user_cohorts/_cohorts_table.html.haml

+.bs-callout.clearfix
+  %p
+    User cohorts are shown for the last twelve months. Only users with
+    activity are counted in the cohort total; inactive users are counted
+    separately.
+
+.table-holder
+  %table.table
+    %thead
+      %tr
+        %th Registration month
+        %th Inactive users
+        %th Cohort total
+        %th Month 0
+        %th Month 1
+        %th Month 2
+        %th Month 3
+        %th Month 4
+        %th Month 5
+        %th Month 6
+        %th Month 7
+        %th Month 8
+        %th Month 9
+        %th Month 10
+        %th Month 11
+    %tbody
+      - @cohorts.each do |registration_month, cohort|
+        %tr
+          %td= registration_month.strftime('%b %Y')
+          %td= number_with_delimiter(cohort[:inactive])
+          %td= number_with_delimiter(cohort[:total])
+          - cohort[:months].each do |running_total|
+            %td
+              - next if cohort[:total].zero?
+              = number_to_percentage(100 * running_total / cohort[:total], precision: 0)
+              %br
+              (#{number_with_delimiter(running_total)})

app/views/admin/user_cohorts/_usage_ping.html.haml

+%h2 Usage ping
+
+.bs-callout.clearfix
+  %p
+    User cohorts are shown because the usage ping is enabled. The data sent with
+    this is shown below. To disable this, visit
+    = succeed '.' do
+      = link_to 'application settings', admin_application_settings_path(anchor: 'usage-statistics')
+
+%pre.usage-data.js-syntax-highlight.code.highlight{ data: { endpoint: usage_data_admin_application_settings_path(format: :html, pretty: true) } }

app/views/admin/user_cohorts/index.html.haml

+- @no_container = true
+= render "admin/dashboard/head"
+
+%div{ class: container_class }
+  - if @cohorts
+    = render 'cohorts_table'
+    = render 'usage_ping'
+  - else
+    .bs-callout.bs-callout-warning.clearfix
+      %p
+        User cohorts are only shown when the
+        = link_to 'usage ping', help_page_path('user/admin_area/settings/usage_statistics', anchor: 'usage-data')
+        usage ping is enabled. It is currently disabled. To enable it and see
+        user cohorts, visit
+        = succeed '.' do
+          = link_to 'application settings', admin_application_settings_path(anchor: 'usage-statistics')

changelogs/unreleased-ee/user-cohorts.yml

+---
+title: Show user cohorts data when usage ping is enabled
+merge_request:
+author:

config/routes/admin.rb

@@ -106,6 +106,8 @@ namespace :admin do
     end
   end
 
+  resources :user_cohorts, only: :index
+
   resources :builds, only: :index do
     collection do
       post :cancel_all

spec/services/user_cohorts_service_spec.rb

+require 'spec_helper'
+
+describe UserCohortsService do
+  describe '#execute' do
+    def month_start(months_ago)
+      months_ago.months.ago.beginning_of_month.to_date
+    end
+
+    # In the interests of speed and clarity, this example has minimal data.
+    it 'returns a list of user cohorts' do
+      6.times do |months_ago|
+        months_ago_time = (months_ago * 2).months.ago
+
+        create(:user, created_at: months_ago_time, current_sign_in_at: Time.now)
+        create(:user, created_at: months_ago_time, current_sign_in_at: months_ago_time)
+      end
+
+      create(:user) # this user is inactive and belongs to the current month
+
+      expected = {
+        month_start(11) => { months: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], total: 0, inactive: 0 },
+        month_start(10) => { months: [2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], total: 2, inactive: 0 },
+        month_start(9) => { months: [0, 0, 0, 0, 0, 0, 0, 0, 0, 0], total: 0, inactive: 0 },
+        month_start(8) => { months: [2, 1, 1, 1, 1, 1, 1, 1, 1], total: 2, inactive: 0 },
+        month_start(7) => { months: [0, 0, 0, 0, 0, 0, 0, 0], total: 0, inactive: 0 },
+        month_start(6) => { months: [2, 1, 1, 1, 1, 1, 1], total: 2, inactive: 0 },
+        month_start(5) => { months: [0, 0, 0, 0, 0, 0], total: 0, inactive: 0 },
+        month_start(4) => { months: [2, 1, 1, 1, 1], total: 2, inactive: 0 },
+        month_start(3) => { months: [0, 0, 0, 0], total: 0, inactive: 0 },
+        month_start(2) => { months: [2, 1, 1], total: 2, inactive: 0 },
+        month_start(1) => { months: [0, 0], total: 0, inactive: 0 },
+        month_start(0) => { months: [2], total: 2, inactive: 1 }
+      }
+
+      result = described_class.new.execute(12)
+
+      expect(result.length).to eq(12)
+      expect(result.keys).to all(be_a(Date))
+      expect(result).to eq(expected)
+    end
+  end
+end