[Fix #264] Add the mean instruction time graph to Stats

app/controllers/stats_controller.rb

@@ -16,6 +16,8 @@ class StatsController < ApplicationController
 
     @procedures_count = procedures.count
     @dossiers_count = dossiers.count
+
+    @dossier_instruction_mean_time = dossier_instruction_mean_time(dossiers)
   end
 
   private
@@ -70,4 +72,46 @@ class StatsController < ApplicationController
       .reduce({}, :merge)
   end
 
+  def mean(collection)
+    (collection.sum.to_f / collection.size).round(2)
+  end
+
+  def dossier_instruction_mean_time(dossiers)
+    # In the 12 last months, we compute for each month
+    # the average time it took to instruct a dossier
+    # We compute monthly averages by first making an average per procedure
+    # and then computing the average for all the procedures
+
+    min_date = 11.months.ago
+    max_date = Time.now.to_date
+
+    processed_dossiers = dossiers
+      .where(:processed_at => min_date..max_date)
+      .pluck(:procedure_id, :initiated_at, :processed_at)
+
+    # Group dossiers by month
+    processed_dossiers_by_month = processed_dossiers
+      .group_by do |dossier|
+        dossier[2].beginning_of_month.to_s
+      end
+
+    processed_dossiers_by_month.map do |month, value|
+      # Group the dossiers for this month by procedure
+      dossiers_grouped_by_procedure = value.group_by { |dossier| dossier[0] }
+
+      # Compute the mean time for this procedure
+      procedure_processing_times = dossiers_grouped_by_procedure.map do |procedure_id, procedure_dossiers|
+        procedure_dossiers_processing_time = procedure_dossiers.map do |dossier|
+          (dossier[2] - dossier[1]).to_f / (3600 * 24)
+        end
+
+        mean(procedure_dossiers_processing_time)
+      end
+
+      # Compute the average mean time for all the procedures of this month
+      month_average = mean(procedure_processing_times)
+
+      [month, month_average]
+    end.to_h
+  end
 end

app/views/stats/index.html.haml

@@ -64,4 +64,13 @@
       %span.big-number-card-number
         = number_with_delimiter(@dossiers_count)
 
+    .stat-card.stat-card-half.pull-left
+      %span.stat-card-title Temps de traitement moyen d'un dossier
+
+      .chart-container
+        .chart
+          = line_chart @dossier_instruction_mean_time,
+            :ytitle => "Jours",
+            :colors => ["rgba(61, 149, 236, 1)"]
+
     .clearfix

spec/controllers/stats_controller_spec.rb

@@ -122,4 +122,52 @@ describe StatsController, type: :controller do
       }) }
     end
   end
+
+  describe "#dossier_instruction_mean_time" do
+    # Month-2: mean 3 days
+    #  procedure_1: mean 2 days
+    #   dossier_p1_a: 3 days
+    #   dossier_p1_b: 1 days
+    #  procedure_2: mean 4 days
+    #    dossier_p2_a: 4 days
+    #
+    # Month-1: mean 5 days
+    #   procedure_1: mean 5 days
+    #     dossier_p1_c: 5 days
+
+    before do
+      procedure_1 = FactoryGirl.create(:procedure)
+      procedure_2 = FactoryGirl.create(:procedure)
+      dossier_p1_a = FactoryGirl.create(:dossier,
+        :procedure    => procedure_1,
+        :initiated_at => 2.months.ago.beginning_of_month,
+        :processed_at => 2.months.ago.beginning_of_month + 3.days)
+      dossier_p1_b = FactoryGirl.create(:dossier,
+        :procedure    => procedure_1,
+        :initiated_at => 2.months.ago.beginning_of_month,
+        :processed_at => 2.months.ago.beginning_of_month + 1.days)
+      dossier_p1_c = FactoryGirl.create(:dossier,
+        :procedure    => procedure_1,
+        :initiated_at => 1.months.ago.beginning_of_month,
+        :processed_at => 1.months.ago.beginning_of_month + 5.days)
+      dossier_p2_a = FactoryGirl.create(:dossier,
+        :procedure    => procedure_2,
+        :initiated_at => 2.month.ago.beginning_of_month,
+        :processed_at => 2.month.ago.beginning_of_month + 4.days)
+
+      # Write directly in the DB to avoid the before_validation hook
+      Dossier.update_all(state: "closed")
+
+      @expected_hash = {
+        "#{2.months.ago.beginning_of_month}" => 3.0,
+        "#{1.months.ago.beginning_of_month}" => 5.0
+      }
+    end
+
+    let (:association) { Dossier.where.not(:state => :draft) }
+
+    subject { StatsController.new.send(:dossier_instruction_mean_time, association) }
+
+    it { expect(subject).to eq(@expected_hash) }
+  end
 end