Add scopes: before and after to annotation model

To make fethcing metrics dashboard annotations easier
we need to add to scopes to allow fetching them by timestamps.

app/finders/metrics/dashboards/annotations_finder.rb

+# frozen_string_literal: true
+
+module Metrics
+  module Dashboards
+    class AnnotationsFinder
+      def initialize(dashboard:, params:)
+        @dashboard, @params = dashboard, params
+      end
+
+      def execute
+        if dashboard.environment
+          apply_filters_to(annotations_for_environment)
+        else
+          Metrics::Dashboard::Annotation.none
+        end
+      end
+
+      private
+
+      attr_reader :dashboard, :params
+
+      def apply_filters_to(annotations)
+        annotations = annotations.after(params[:from]) if params[:from].present?
+        annotations = annotations.before(params[:to]) if params[:to].present? && valid_timespan_boundaries?
+
+        by_dashboard(annotations)
+      end
+
+      def annotations_for_environment
+        dashboard.environment.metrics_dashboard_annotations
+      end
+
+      def by_dashboard(annotations)
+        annotations.for_dashboard(dashboard.path)
+      end
+
+      def valid_timespan_boundaries?
+        params[:from].blank? || params[:to] >= params[:from]
+      end
+    end
+  end
+end

app/models/metrics/dashboard/annotation.rb

@@ -15,6 +15,11 @@ module Metrics
       validate :single_ownership
       validate :orphaned_annotation
 
+      scope :after, ->(after) { where('starting_at >= ?', after) }
+      scope :before, ->(before) { where('starting_at <= ?', before) }
+
+      scope :for_dashboard, ->(dashboard_path) { where(dashboard_path: dashboard_path) }
+
       private
 
       def single_ownership

spec/finders/metrics/dashboards/annotations_finder_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Metrics::Dashboards::AnnotationsFinder do
+  describe '#execute' do
+    subject(:annotations) { described_class.new(dashboard: dashboard, params: params).execute }
+
+    let_it_be(:current_user) { create(:user) }
+    let(:path) { 'config/prometheus/common_metrics.yml' }
+    let(:params) { {} }
+    let(:environment) { create(:environment) }
+    let(:dashboard) { PerformanceMonitoring::PrometheusDashboard.new(path: path, environment: environment) }
+
+    context 'there are no annotations records' do
+      it 'returns empty array' do
+        expect(annotations).to be_empty
+      end
+    end
+
+    context 'with annotation records' do
+      let!(:nine_minutes_old_annotation) { create(:metrics_dashboard_annotation, environment: environment, starting_at: 9.minutes.ago, dashboard_path: path) }
+      let!(:fifteen_minutes_old_annotation) { create(:metrics_dashboard_annotation, environment: environment, starting_at: 15.minutes.ago, dashboard_path: path) }
+      let!(:just_created_annotation) { create(:metrics_dashboard_annotation, environment: environment, dashboard_path: path) }
+      let!(:annotation_for_different_env) { create(:metrics_dashboard_annotation, dashboard_path: path) }
+      let!(:annotation_for_different_dashboard) { create(:metrics_dashboard_annotation, dashboard_path: '.gitlab/dashboards/test.yml') }
+
+      it 'loads annotations' do
+        expect(annotations).to match_array [fifteen_minutes_old_annotation, nine_minutes_old_annotation, just_created_annotation]
+      end
+
+      context 'when the from filter is present' do
+        let(:params) do
+          {
+            from: 14.minutes.ago
+          }
+        end
+
+        it 'loads only younger annotations' do
+          expect(annotations).to match_array [nine_minutes_old_annotation, just_created_annotation]
+        end
+      end
+
+      context 'when the to filter is present' do
+        let(:params) do
+          {
+            to: 5.minutes.ago
+          }
+        end
+
+        it 'loads only older annotations' do
+          expect(annotations).to match_array [fifteen_minutes_old_annotation, nine_minutes_old_annotation]
+        end
+      end
+
+      context 'when from and to filters are present' do
+        context 'and to is bigger than from' do
+          let(:params) do
+            {
+              from: 14.minutes.ago,
+              to: 5.minutes.ago
+            }
+          end
+
+          it 'loads only annotations assigned to this interval' do
+            expect(annotations).to match_array [nine_minutes_old_annotation]
+          end
+        end
+
+        context 'and from is bigger than to' do
+          let(:params) do
+            {
+              to: 14.minutes.ago,
+              from: 5.minutes.ago
+            }
+          end
+
+          it 'ignores to parameter and returns annotations starting at from filter' do
+            expect(annotations).to match_array [just_created_annotation]
+          end
+        end
+
+        context 'when from or to filters are empty strings' do
+          let(:params) do
+            {
+              from: '',
+              to: ''
+            }
+          end
+
+          it 'ignores this parameters' do
+            expect(annotations).to match_array [fifteen_minutes_old_annotation, nine_minutes_old_annotation, just_created_annotation]
+          end
+        end
+      end
+
+      context 'dashboard environment is missing' do
+        let(:dashboard) { PerformanceMonitoring::PrometheusDashboard.new(path: path, environment: nil) }
+
+        it 'returns empty relation', :aggregate_failures do
+          expect(annotations).to be_kind_of ::ActiveRecord::Relation
+          expect(annotations).to be_empty
+        end
+      end
+    end
+  end
+end

spec/models/metrics/dashboard/annotation_spec.rb

@@ -50,4 +50,30 @@ describe Metrics::Dashboard::Annotation do
       end
     end
   end
+
+  describe 'scopes' do
+    let_it_be(:nine_minutes_old_annotation) { create(:metrics_dashboard_annotation, starting_at: 9.minutes.ago) }
+    let_it_be(:fifteen_minutes_old_annotation) { create(:metrics_dashboard_annotation, starting_at: 15.minutes.ago) }
+    let_it_be(:just_created_annotation) { create(:metrics_dashboard_annotation) }
+
+    describe '#after' do
+      it 'returns only younger annotations' do
+        expect(described_class.after(12.minutes.ago)).to match_array [nine_minutes_old_annotation, just_created_annotation]
+      end
+    end
+
+    describe '#before' do
+      it 'returns only older annotations' do
+        expect(described_class.before(5.minutes.ago)).to match_array [fifteen_minutes_old_annotation, nine_minutes_old_annotation]
+      end
+    end
+
+    describe '#for_dashboard' do
+      let!(:other_dashboard_annotation) { create(:metrics_dashboard_annotation, dashboard_path: 'other_dashboard.yml') }
+
+      it 'returns annotations only for appointed dashboard' do
+        expect(described_class.for_dashboard('other_dashboard.yml')).to match_array [other_dashboard_annotation]
+      end
+    end
+  end
 end