Query backend for tasks by type chart

Query for getting counts by date for Issue or MergeRequest records
within a group. This query object is going to be used for the tasks
by type chart.

ee/app/controllers/analytics/tasks_by_type_controller.rb

@@ -9,24 +9,6 @@ class Analytics::TasksByTypeController < Analytics::ApplicationController
   before_action :validate_label_ids
   before_action :prepare_date_range
 
-  # Mocked data, this will be replaced with real implementation
-  class TasksByType
-    LabelCountResult = Struct.new(:label, :series)
-
-    def counts_by_labels
-      [
-        LabelCountResult.new(GroupLabel.new(id: 1, title: 'label 1'), [
-          ["2018-01-01", 23],
-          ["2018-01-02", 5]
-        ]),
-        LabelCountResult.new(GroupLabel.new(id: 2, title: 'label 3'), [
-          ["2018-01-01", 3],
-          ["2018-01-03", 10]
-        ])
-      ]
-    end
-  end
-
   def show
     render json: Analytics::TasksByTypeLabelEntity.represent(counts_by_labels)
   end
@@ -34,7 +16,13 @@ class Analytics::TasksByTypeController < Analytics::ApplicationController
   private
 
   def counts_by_labels
-    TasksByType.new.counts_by_labels
+    Gitlab::Analytics::TypeOfWork::TasksByType.new(group: @group, current_user: current_user, params: {
+      subject: params[:subject],
+      label_ids: Array(params[:label_ids]),
+      project_ids: Array(params[:project_ids]),
+      created_after: @created_after.to_time.utc.beginning_of_day,
+      created_before: @created_before.to_time.utc.end_of_day
+    }).counts_by_labels
   end
 
   def validate_label_ids

ee/changelogs/unreleased/32454-tasks-by-type-chart-backend.yml

+---
+title: Data API endpoint for tasks by type chart within the analytics workspace
+merge_request: 17944
+author:
+type: added

ee/lib/gitlab/analytics/type_of_work/tasks_by_type.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Analytics
+    module TypeOfWork
+      class TasksByType
+        LabelCountResult = Struct.new(:label, :series)
+
+        FINDER_CLASSES = {
+          MergeRequest.to_s => MergeRequestsFinder,
+          Issue.to_s => IssuesFinder
+        }.freeze
+
+        def initialize(group:, params:, current_user:)
+          @group = group
+          @params = params
+          @finder = finder_class.new(current_user, finder_params)
+        end
+
+        def counts_by_labels
+          format_result(query_result)
+        end
+
+        private
+
+        attr_reader :group, :params, :finder
+
+        def finder_class
+          FINDER_CLASSES.fetch(params[:subject], FINDER_CLASSES.keys.first)
+        end
+
+        def format_result(result)
+          result.each_with_object({}) do |((label_id, date), count), hash|
+            label = labels_by_id.fetch(label_id)
+
+            hash[label_id] ||= LabelCountResult.new(label, [])
+            hash[label_id].series << [date, count]
+          end.values
+        end
+
+        def finder_params
+          { include_subgroups: true, group_id: group.id }.merge(params.slice(:created_after, :created_before))
+        end
+
+        # rubocop: disable CodeReuse/ActiveRecord
+        def query_result
+          finder
+            .execute
+            .joins(:label_links)
+            .where(filters)
+            .group(label_id_column, date_column)
+            .reorder(nil)
+            .count(subject_table[:id])
+        end
+
+        def filters
+          {}.tap do |hash|
+            hash[:label_links] = { label_id: labels_by_id.keys }
+            hash[:project_id] = params[:project_ids] unless params[:project_ids].blank?
+          end
+        end
+
+        def labels
+          @labels ||= GroupLabel.where(id: params[:label_ids])
+        end
+
+        # rubocop: enable CodeReuse/ActiveRecord
+
+        def label_id_column
+          LabelLink.arel_table[:label_id]
+        end
+
+        # Generating `DATE(created_at)` string
+        def date_column
+          Arel::Nodes::NamedFunction.new('DATE', [subject_table[:created_at]]).to_sql
+        end
+
+        def subject_table
+          finder.klass.arel_table
+        end
+
+        def labels_by_id
+          @labels_by_id = labels.each_with_object({}) { |label, hash| hash[label.id] = label }
+        end
+      end
+    end
+  end
+end

ee/spec/controllers/analytics/tasks_by_type_controller_spec.rb

@@ -5,18 +5,20 @@ require 'spec_helper'
 describe Analytics::TasksByTypeController do
   let(:user) { create(:user) }
   let(:group) { create(:group) }
-  let(:params) { { group_id: group.full_path, label_ids: [1, 2], created_after: '2018-01-01' } }
-  let(:subject) { get :show, params: params }
+  let(:label) { create(:group_label, group: group) }
+  let(:params) { { group_id: group.full_path, label_ids: [label.id], created_after: 10.days.ago, subject: 'Issue' } }
+  let!(:issue) { create(:labeled_issue, created_at: 5.days.ago, project: create(:project, group: group), labels: [label]) }
+  subject { get :show, params: params }
 
   before do
     stub_licensed_features(type_of_work_analytics: true)
     stub_feature_flags(Gitlab::Analytics::TASKS_BY_TYPE_CHART_FEATURE_FLAG => true)
 
     group.add_reporter(user)
-
     sign_in(user)
   end
 
+  context 'when valid parameters are given' do
     it 'succeeds' do
       subject
 
@@ -24,6 +26,15 @@ describe Analytics::TasksByTypeController do
       expect(response).to match_response_schema('analytics/tasks_by_type', dir: 'ee')
     end
 
+    it 'returns valid count' do
+      subject
+
+      date, count = json_response.first["series"].first
+      expect(Date.parse(date)).to eq(issue.created_at.to_date)
+      expect(count).to eq(1)
+    end
+  end
+
   context 'when user access level is lower than reporter' do
     before do
       group.add_guest(user)

ee/spec/lib/gitlab/analytics/type_of_work/tasks_by_type_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Analytics::TypeOfWork::TasksByType do
+  let_it_be(:user) { create(:user) }
+  let_it_be(:group) { create(:group) }
+  let_it_be(:other_group) { create(:group) }
+  let_it_be(:subgroup) { create(:group, parent: group) }
+  let_it_be(:label) { create(:group_label, group: group) }
+  let_it_be(:label_for_subgroup) { create(:group_label, group: group) }
+  let_it_be(:other_label) { create(:group_label, group: other_group) }
+  let_it_be(:project) { create(:project, group: group) }
+
+  let(:params) do
+    {
+      group: group,
+      params: { label_ids: [label.id, label_for_subgroup.id], created_after: 10.days.ago, created_before: Date.today },
+      current_user: user
+    }
+  end
+
+  subject do
+    described_class.new(params).counts_by_labels
+  end
+
+  around do |example|
+    Timecop.freeze { example.run }
+  end
+
+  before do
+    group.add_reporter(user)
+  end
+
+  shared_examples '#counts_by_labels' do
+    let!(:with_label) do
+      create(factory_name, {
+        :created_at => 3.days.ago,
+        :labels => [label],
+        project_attribute_name => project
+      })
+    end
+
+    let!(:with_label_on_other_date) do
+      create(factory_name, {
+        :created_at => 2.days.ago,
+        :labels => [label],
+        project_attribute_name => create(:project, group: group)
+      })
+    end
+
+    let!(:with_subgroup) do
+      create(factory_name, {
+        :created_at => 3.days.ago,
+        :labels => [label, label_for_subgroup],
+        project_attribute_name => create(:project, group: subgroup)
+      })
+    end
+
+    let!(:outside_group) do
+      create(factory_name, {
+        :created_at => 3.days.ago,
+        :labels => [other_label],
+        project_attribute_name => create(:project, group: other_group)
+      })
+    end
+
+    def label_count_for(label, result)
+      label_count_result = result.find { |r| r.label.id == label.id }
+      label_count_result.series.sum(&:last) # format: [DATE, COUNT]
+    end
+
+    it 'counts the records by label and date' do
+      expect(label_count_for(label, subject)).to eq(3)
+    end
+
+    it 'counts should include subgroups' do
+      expect(label_count_for(label_for_subgroup, subject)).to eq(1)
+    end
+
+    it 'does not include count from outside of the group' do
+      label_ids = subject.map { |r| r.label.id }
+
+      expect(label_ids).to contain_exactly(label.id, label_for_subgroup.id)
+    end
+
+    context 'when group without any record is given' do
+      before do
+        params[:group] = create(:group)
+      end
+
+      it { expect(subject).to be_empty }
+    end
+
+    context 'when no labels are given' do
+      before do
+        params[:params][:label_ids] = []
+      end
+
+      it { expect(subject).to be_empty }
+    end
+
+    context 'when records are outside of the given time range' do
+      before do
+        params[:params][:created_after] = 2.years.ago
+        params[:params][:created_before] = 1.year.ago
+      end
+
+      it { expect(subject).to be_empty }
+    end
+
+    context 'when filtering by `project_ids`' do
+      before do
+        params[:params][:project_ids] = [project.id]
+      end
+
+      it { expect(label_count_for(label, subject)).to eq(1) }
+    end
+  end
+
+  context 'when subject is `Issue`' do
+    let(:factory_name) { :labeled_issue }
+    let(:project_attribute_name) { :project }
+
+    before do
+      params[:params][:subject] = Issue.to_s
+    end
+
+    include_examples '#counts_by_labels'
+  end
+
+  context 'when subject is `MergeRequest`' do
+    let(:factory_name) { :labeled_merge_request }
+    let(:project_attribute_name) { :source_project }
+
+    before do
+      params[:params][:subject] = MergeRequest.to_s
+    end
+
+    include_examples '#counts_by_labels'
+  end
+end