# frozen_string_literal: true

require 'spec_helper'

RSpec.describe Gitlab::Utils::UsageData do
  include Database::DatabaseHelpers

  shared_examples 'failing hardening method' do |raised_exception|
    let(:exception) { raised_exception || ActiveRecord::StatementInvalid }

    before do
      allow(Gitlab::ErrorTracking).to receive(:should_raise_for_dev?).and_return(should_raise_for_dev)
      stub_const("Gitlab::Utils::UsageData::FALLBACK", fallback)
      allow(failing_class).to receive(failing_method).and_raise(exception) unless failing_class.nil?
    end

    context 'with should_raise_for_dev? false' do
      let(:should_raise_for_dev) { false }

      it 'returns the fallback' do
        expect(subject).to eq(fallback)
      end
    end

    context 'with should_raise_for_dev? true' do
      let(:should_raise_for_dev) { true }

      it 'raises an error' do
        expect { subject }.to raise_error(exception)
      end
    end
  end

  describe '.with_metadata' do
    it 'yields passed block' do
      expect { |block| described_class.with_metadata(&block) }.to yield_with_no_args
    end
  end

  describe '#add_metric' do
    let(:metric) { 'UuidMetric' }

    it 'computes the metric value for given metric' do
      expect(described_class.add_metric(metric)).to eq(Gitlab::CurrentSettings.uuid)
    end
  end

  describe '#count' do
    let(:relation) { double(:relation) }

    it 'returns the count when counting succeeds' do
      allow(relation).to receive(:count).and_return(1)

      expect(described_class.count(relation, batch: false)).to eq(1)
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)
      allow(relation).to receive(:count).and_return(1)

      described_class.count(relation, batch: false)
    end

    context 'when counting fails' do
      subject { described_class.count(relation, batch: false) }

      let(:fallback) { 15 }
      let(:failing_class) { relation }
      let(:failing_method) { :count }

      it_behaves_like 'failing hardening method'
    end
  end

  describe '#distinct_count' do
    let(:relation) { double(:relation) }

    it 'returns the count when counting succeeds' do
      allow(relation).to receive(:distinct_count_by).and_return(1)

      expect(described_class.distinct_count(relation, batch: false)).to eq(1)
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)
      allow(relation).to receive(:distinct_count_by).and_return(1)

      described_class.distinct_count(relation, batch: false)
    end

    context 'when counting fails' do
      subject { described_class.distinct_count(relation, batch: false) }

      let(:fallback) { 15 }
      let(:failing_class) { relation }
      let(:failing_method) { :distinct_count_by }

      it_behaves_like 'failing hardening method'
    end
  end

  describe '#estimate_batch_distinct_count' do
    let(:error_rate) { Gitlab::Database::PostgresHll::BatchDistinctCounter::ERROR_RATE } # HyperLogLog is a probabilistic algorithm, which provides estimated data, with given error margin
    let(:relation) { double(:relation, connection: double(:connection)) }

    before do
      allow(relation.connection).to receive(:transaction_open?).and_return(false)
    end

    it 'delegates counting to counter class instance' do
      buckets = instance_double(Gitlab::Database::PostgresHll::Buckets)

      expect_next_instance_of(Gitlab::Database::PostgresHll::BatchDistinctCounter, relation, 'column') do |instance|
        expect(instance).to receive(:execute)
                              .with(batch_size: nil, start: nil, finish: nil)
                              .and_return(buckets)
      end
      expect(buckets).to receive(:estimated_distinct_count).and_return(5)

      expect(described_class.estimate_batch_distinct_count(relation, 'column')).to eq(5)
    end

    it 'yield provided block with PostgresHll::Buckets' do
      buckets = Gitlab::Database::PostgresHll::Buckets.new

      allow_next_instance_of(Gitlab::Database::PostgresHll::BatchDistinctCounter) do |instance|
        allow(instance).to receive(:execute).and_return(buckets)
      end

      expect { |block| described_class.estimate_batch_distinct_count(relation, 'column', &block) }.to yield_with_args(buckets)
    end

    context 'quasi integration test for different counting parameters' do
      # HyperLogLog http://algo.inria.fr/flajolet/Publications/FlFuGaMe07.pdf algorithm
      # used in estimate_batch_distinct_count produce probabilistic
      # estimations of unique values present in dataset, because of that its results
      # are always off by some small factor from real value. However for given
      # dataset it provide consistent and deterministic result. In the following context
      # analyzed sets consist of values:
      # build_needs set: ['1', '2', '3', '4', '5']
      # ci_build set ['a', 'b']
      # with them, current implementation is expected to consistently report
      # the same static values
      # This test suite is expected to assure, that HyperLogLog implementation
      # behaves consistently between changes made to other parts of codebase.
      # In case of fine tuning or changes to HyperLogLog algorithm implementation
      # one should run in depth analysis of accuracy with supplementary rake tasks
      # currently under implementation at https://gitlab.com/gitlab-org/gitlab/-/merge_requests/51118
      # and adjust used values in this context accordingly.
      let_it_be(:build) { create(:ci_build, name: 'a') }
      let_it_be(:another_build) { create(:ci_build, name: 'b') }

      let(:model) { Ci::BuildNeed }
      let(:column) { :name }
      let(:build_needs_estimated_cardinality) { 5.024574181542231 }
      let(:ci_builds_estimated_cardinality) { 2.003916452421793 }

      before do
        allow(model.connection).to receive(:transaction_open?).and_return(false)
      end

      context 'different counting parameters' do
        before_all do
          1.upto(3) { |i| create(:ci_build_need, name: i, build: build) }
          4.upto(5) { |i| create(:ci_build_need, name: i, build: another_build) }
        end

        it 'counts with symbol passed in column argument' do
          expect(described_class.estimate_batch_distinct_count(model, column)).to eq(build_needs_estimated_cardinality)
        end

        it 'counts with string passed in column argument' do
          expect(described_class.estimate_batch_distinct_count(model, column.to_s)).to eq(build_needs_estimated_cardinality)
        end

        it 'counts with table.column passed in column argument' do
          expect(described_class.estimate_batch_distinct_count(model, "#{model.table_name}.#{column}")).to eq(build_needs_estimated_cardinality)
        end

        it 'counts with Arel passed in column argument' do
          expect(described_class.estimate_batch_distinct_count(model, model.arel_table[column])).to eq(build_needs_estimated_cardinality)
        end

        it 'counts over joined relations' do
          expect(described_class.estimate_batch_distinct_count(model.joins(:build), "#{Ci::Build.table_name}.name")).to eq(ci_builds_estimated_cardinality)
        end

        it 'counts with :column field with batch_size of 50K' do
          expect(described_class.estimate_batch_distinct_count(model, column, batch_size: 50_000)).to eq(build_needs_estimated_cardinality)
        end

        it 'counts with different number of batches and aggregates total result' do
          stub_const('Gitlab::Database::PostgresHll::BatchDistinctCounter::MIN_REQUIRED_BATCH_SIZE', 0)

          [1, 2, 4, 5, 6].each { |i| expect(described_class.estimate_batch_distinct_count(model, column, batch_size: i)).to eq(build_needs_estimated_cardinality) }
        end

        it 'counts with a start and finish' do
          expect(described_class.estimate_batch_distinct_count(model, column, start: model.minimum(:id), finish: model.maximum(:id))).to eq(build_needs_estimated_cardinality)
        end
      end
    end

    describe 'error handling' do
      before do
        stub_const("Gitlab::Utils::UsageData::FALLBACK", 3)
        stub_const("Gitlab::Utils::UsageData::DISTRIBUTED_HLL_FALLBACK", 4)
      end

      context 'when counter raises WRONG_CONFIGURATION_ERROR' do
        subject { described_class.estimate_batch_distinct_count(relation, 'id', start: 1, finish: 0) }

        let(:fallback) { 3 }
        let(:failing_class) { Gitlab::Database::PostgresHll::BatchDistinctCounter }
        let(:failing_method) { :new }

        it_behaves_like 'failing hardening method'
      end

      context 'when counting fails due to database error' do
        subject { described_class.estimate_batch_distinct_count(relation) }

        let(:fallback) { 3 }
        let(:failing_class) { Gitlab::Database::PostgresHll::BatchDistinctCounter }
        let(:failing_method) { :new }

        it_behaves_like 'failing hardening method'
      end
    end
  end

  describe '#sum' do
    let(:relation) { double(:relation) }

    it 'returns the count when counting succeeds' do
      allow(Gitlab::Database::BatchCount)
        .to receive(:batch_sum)
        .with(relation, :column, batch_size: 100, start: 2, finish: 3)
        .and_return(1)

      expect(described_class.sum(relation, :column, batch_size: 100, start: 2, finish: 3)).to eq(1)
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)
      allow(Gitlab::Database::BatchCount).to receive(:batch_sum).and_return(1)

      described_class.sum(relation, :column)
    end

    context 'when counting fails' do
      subject { described_class.sum(relation, :column) }

      let(:fallback) { 15 }
      let(:failing_class) { Gitlab::Database::BatchCount }
      let(:failing_method) { :batch_sum }

      it_behaves_like 'failing hardening method'
    end
  end

  describe '#average' do
    let(:relation) { double(:relation) }

    it 'returns the average when operation succeeds' do
      allow(Gitlab::Database::BatchCount)
        .to receive(:batch_average)
        .with(relation, :column, batch_size: 100, start: 2, finish: 3)
        .and_return(1)

      expect(described_class.average(relation, :column, batch_size: 100, start: 2, finish: 3)).to eq(1)
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)

      allow(Gitlab::Database::BatchCount).to receive(:batch_average).and_return(1)

      described_class.average(relation, :column)
    end

    context 'when operation fails' do
      subject { described_class.average(relation, :column) }

      let(:fallback) { 15 }
      let(:failing_class) { Gitlab::Database::BatchCount }
      let(:failing_method) { :batch_average }

      it_behaves_like 'failing hardening method'
    end
  end

  describe '#histogram' do
    let_it_be(:projects) { create_list(:project, 3) }

    let(:project1) { projects.first }
    let(:project2) { projects.second }
    let(:project3) { projects.third }

    let(:fallback) { described_class::HISTOGRAM_FALLBACK }
    let(:relation) { AlertManagement::HttpIntegration.active }
    let(:column) { :project_id }

    def expect_error(exception, message, &block)
      expect(Gitlab::ErrorTracking)
        .to receive(:track_and_raise_for_dev_exception)
        .with(instance_of(exception))
        .and_call_original

      expect(&block).to raise_error(
        an_instance_of(exception).and(
          having_attributes(message: message, backtrace: be_kind_of(Array)))
      )
    end

    it 'checks bucket bounds to be not equal' do
      expect_error(ArgumentError, 'Lower bucket bound cannot equal to upper bucket bound') do
        described_class.histogram(relation, column, buckets: 1..1)
      end
    end

    it 'checks bucket_size being non-zero' do
      expect_error(ArgumentError, 'Bucket size cannot be zero') do
        described_class.histogram(relation, column, buckets: 1..2, bucket_size: 0)
      end
    end

    it 'limits the amount of buckets without providing bucket_size argument' do
      expect_error(ArgumentError, 'Bucket size 101 exceeds the limit of 100') do
        described_class.histogram(relation, column, buckets: 1..101)
      end
    end

    it 'limits the amount of buckets when providing bucket_size argument' do
      expect_error(ArgumentError, 'Bucket size 101 exceeds the limit of 100') do
        described_class.histogram(relation, column, buckets: 1..2, bucket_size: 101)
      end
    end

    it 'without data' do
      histogram = described_class.histogram(relation, column, buckets: 1..100)

      expect(histogram).to eq({})
    end

    it 'aggregates properly within bounds' do
      create(:alert_management_http_integration, :active, project: project1)
      create(:alert_management_http_integration, :inactive, project: project1)

      create(:alert_management_http_integration, :active, project: project2)
      create(:alert_management_http_integration, :active, project: project2)
      create(:alert_management_http_integration, :inactive, project: project2)

      create(:alert_management_http_integration, :active, project: project3)
      create(:alert_management_http_integration, :inactive, project: project3)

      histogram = described_class.histogram(relation, column, buckets: 1..100)

      expect(histogram).to eq('1' => 2, '2' => 1)
    end

    it 'aggregates properly out of bounds' do
      create_list(:alert_management_http_integration, 3, :active, project: project1)
      histogram = described_class.histogram(relation, column, buckets: 1..2)

      expect(histogram).to eq('2' => 1)
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)

      described_class.histogram(relation, column, buckets: 1..100)
    end

    context 'when query timeout' do
      subject do
        with_statement_timeout(0.001, connection: ApplicationRecord.connection) do
          relation = AlertManagement::HttpIntegration.select('pg_sleep(0.002)')
          described_class.histogram(relation, column, buckets: 1..100)
        end
      end

      before do
        allow(Gitlab::ErrorTracking).to receive(:should_raise_for_dev?).and_return(should_raise_for_dev)
        create(:alert_management_http_integration, :active, project: project1)
      end

      context 'with should_raise_for_dev? false' do
        let(:should_raise_for_dev) { false }

        it 'logs canceled queries' do
          expect(Gitlab::AppJsonLogger).to receive(:error).with(
            event: 'histogram',
            relation: relation.table_name,
            operation: 'histogram',
            operation_args: [column, 1, 100, 99],
            query: kind_of(String),
            message: /PG::QueryCanceled/
          )
          subject
        end

        it 'returns fallback' do
          expect(subject).to eq(fallback)
        end
      end

      context 'with should_raise_for_dev? true' do
        let(:should_raise_for_dev) { true }

        it 'raises error' do
          expect { subject }.to raise_error(ActiveRecord::QueryCanceled)
        end
      end
    end
  end

  describe '#add' do
    it 'adds given values' do
      expect(described_class.add(1, 3)).to eq(4)
    end

    it 'adds given values' do
      expect(described_class.add).to eq(0)
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)

      described_class.add
    end

    context 'when adding fails' do
      subject { described_class.add(nil, 3) }

      let(:fallback) { -1 }
      let(:failing_class) { nil }

      it_behaves_like 'failing hardening method', StandardError
    end

    it 'returns the fallback value one of the arguments is negative' do
      expect(described_class.add(-1, 1)).to eq(-1)
    end
  end

  describe '#alt_usage_data' do
    context 'when method fails' do
      subject { described_class.alt_usage_data { raise StandardError } }

      let(:fallback) { -1 }
      let(:failing_class) { nil }

      it_behaves_like 'failing hardening method', StandardError
    end

    it 'records duration' do
      expect(described_class).to receive(:with_metadata)

      described_class.alt_usage_data
    end

    it 'returns the evaluated block when give' do
      expect(described_class.alt_usage_data { Gitlab::CurrentSettings.uuid }).to eq(Gitlab::CurrentSettings.uuid)
    end

    it 'returns the value when given' do
      expect(described_class.alt_usage_data(1)).to eq 1
    end
  end

  describe '#redis_usage_data' do
    it 'records duration' do
      result = described_class.redis_usage_data

      expect(result.duration).to be_present
    end

    context 'with block given' do
      context 'when method fails' do
        subject { described_class.redis_usage_data { raise ::Redis::CommandError } }

        let(:fallback) { -1 }
        let(:failing_class) { nil }

        it_behaves_like 'failing hardening method', ::Redis::CommandError
      end

      context 'when Redis HLL raises any error' do
        subject { described_class.redis_usage_data { raise Gitlab::UsageDataCounters::HLLRedisCounter::EventError } }

        let(:fallback) { 15 }
        let(:failing_class) { nil }

        it_behaves_like 'failing hardening method', Gitlab::UsageDataCounters::HLLRedisCounter::EventError
      end

      it 'returns the evaluated block when given' do
        expect(described_class.redis_usage_data { 1 }).to eq(1)
      end
    end

    context 'with counter given' do
      context 'when gets an error' do
        subject { described_class.redis_usage_data(::Gitlab::UsageDataCounters::MergeRequestWidgetExtensionCounter) }

        let(:fallback) { ::Gitlab::UsageDataCounters::MergeRequestWidgetExtensionCounter.fallback_totals }
        let(:failing_class) { ::Gitlab::UsageDataCounters::MergeRequestWidgetExtensionCounter }
        let(:failing_method) { :totals }

        it_behaves_like 'failing hardening method', ::Redis::CommandError
      end

      it 'returns the totals when counter is given' do
        allow(::Gitlab::UsageDataCounters::MergeRequestWidgetExtensionCounter).to receive(:totals).and_return({ merge_request_create: 2 })
        expect(described_class.redis_usage_data(::Gitlab::UsageDataCounters::MergeRequestWidgetExtensionCounter)).to eql({ merge_request_create: 2 })
      end
    end
  end

  describe '#with_prometheus_client' do
    it 'records duration' do
      expect(described_class).to receive(:with_metadata)

      described_class.with_prometheus_client { |client| client }
    end

    it 'returns fallback with for an exception in yield block' do
      allow(described_class).to receive(:prometheus_client).and_return(Gitlab::PrometheusClient.new('http://localhost:9090'))
      result = described_class.with_prometheus_client(fallback: -42) { |client| raise StandardError }

      expect(result).to be(-42)
    end

    shared_examples 'query data from Prometheus' do
      it 'yields a client instance and returns the block result' do
        result = described_class.with_prometheus_client { |client| client }

        expect(result).to be_an_instance_of(Gitlab::PrometheusClient)
      end
    end

    shared_examples 'does not query data from Prometheus' do
      it 'returns {} by default' do
        result = described_class.with_prometheus_client { |client| client }

        expect(result).to eq({})
      end

      it 'returns fallback if provided' do
        result = described_class.with_prometheus_client(fallback: []) { |client| client }

        expect(result).to eq([])
      end
    end

    shared_examples 'try to query Prometheus with given address' do
      context 'Prometheus is ready' do
        before do
          stub_request(:get, %r{/-/ready})
              .to_return(status: 200, body: 'Prometheus is Ready.\n')
        end

        context 'Prometheus is reachable through HTTPS' do
          it_behaves_like 'query data from Prometheus'
        end

        context 'Prometheus is not reachable through HTTPS' do
          before do
            stub_request(:get, %r{https://.*}).to_raise(Errno::ECONNREFUSED)
          end

          context 'Prometheus is reachable through HTTP' do
            it_behaves_like 'query data from Prometheus'
          end

          context 'Prometheus is not reachable through HTTP' do
            before do
              stub_request(:get, %r{http://.*}).to_raise(Errno::ECONNREFUSED)
            end

            it_behaves_like 'does not query data from Prometheus'
          end
        end
      end

      context 'Prometheus is not ready' do
        before do
          stub_request(:get, %r{/-/ready})
              .to_return(status: 503, body: 'Service Unavailable')
        end

        it_behaves_like 'does not query data from Prometheus'
      end
    end

    context 'when Prometheus server address is available from settings' do
      before do
        expect(Gitlab::Prometheus::Internal).to receive(:prometheus_enabled?).and_return(true)
        expect(Gitlab::Prometheus::Internal).to receive(:uri).and_return('http://prom:9090')
      end

      it_behaves_like 'try to query Prometheus with given address'
    end

    context 'when Prometheus server address is available from Consul service discovery' do
      before do
        expect(Gitlab::Prometheus::Internal).to receive(:prometheus_enabled?).and_return(false)
        expect(Gitlab::Consul::Internal).to receive(:api_url).and_return('http://localhost:8500')
        expect(Gitlab::Consul::Internal).to receive(:discover_prometheus_server_address).and_return('prom:9090')
      end

      it_behaves_like 'try to query Prometheus with given address'
    end

    context 'when Prometheus server address is not available' do
      before do
        expect(Gitlab::Prometheus::Internal).to receive(:prometheus_enabled?).and_return(false)
        expect(Gitlab::Consul::Internal).to receive(:api_url).and_return(nil)
      end

      it_behaves_like 'does not query data from Prometheus'
    end
  end

  describe '#measure_duration' do
    it 'returns block result and execution duration' do
      allow(Process).to receive(:clock_gettime).and_return(1, 3)

      result, duration = described_class.measure_duration { 42 }

      expect(result).to eq(42)
      expect(duration).to eq(2)
    end
  end

  describe '#with_finished_at' do
    it 'adds a timestamp to the hash yielded by the block' do
      freeze_time do
        result = described_class.with_finished_at(:current_time) { { a: 1 } }

        expect(result).to eq(a: 1, current_time: Time.current)
      end
    end
  end

  describe '#track_usage_event' do
    let(:value) { '9f302fea-f828-4ca9-aef4-e10bd723c0b3' }
    let(:event_name) { 'incident_management_alert_status_changed' }
    let(:unknown_event) { 'unknown' }

    it 'tracks redis hll event' do
      expect(Gitlab::UsageDataCounters::HLLRedisCounter).to receive(:track_event).with(event_name, values: value)

      described_class.track_usage_event(event_name, value)
    end

    it 'raise an error for unknown event' do
      expect { described_class.track_usage_event(unknown_event, value) }.to raise_error(Gitlab::UsageDataCounters::HLLRedisCounter::UnknownEvent)
    end
  end

  describe 'min/max' do
    let(:model) { double(:relation) }

    it 'returns min from the model' do
      allow(model).to receive(:minimum).and_return(2)
      allow(model).to receive(:name).and_return('sample_min_model')

      expect(described_class.minimum_id(model)).to eq(2)
    end

    it 'returns max from the model' do
      allow(model).to receive(:maximum).and_return(100)
      allow(model).to receive(:name).and_return('sample_max_model')

      expect(described_class.maximum_id(model)).to eq(100)
    end
  end
end
