# frozen_string_literal: true

RSpec.shared_examples 'it runs batched background migration jobs' do |tracking_database, table_name|
  include ExclusiveLeaseHelpers

  before do
    stub_feature_flags(disallow_database_ddl_feature_flags: false)
  end

  describe 'defining the job attributes' do
    it 'defines the data_consistency as always' do
      expect(described_class.get_data_consistency).to eq(:always)
    end

    it 'defines the feature_category as database' do
      expect(described_class.get_feature_category).to eq(:database)
    end

    it 'defines the idempotency as true' do
      expect(described_class.idempotent?).to be_truthy
    end
  end

  describe '.tracking_database' do
    it 'does not raise an error' do
      expect { described_class.tracking_database }.not_to raise_error
    end

    it 'overrides the method to return the tracking database' do
      expect(described_class.tracking_database).to eq(tracking_database)
    end
  end

  describe '.lease_key' do
    let(:lease_key) { described_class.name.demodulize.underscore }

    it 'does not raise an error' do
      expect { described_class.lease_key }.not_to raise_error
    end

    it 'returns the lease key' do
      expect(described_class.lease_key).to eq(lease_key)
    end
  end

  describe '.enabled?' do
    it 'returns true when execute_batched_migrations_on_schedule feature flag is enabled' do
      stub_feature_flags(execute_batched_migrations_on_schedule: true)

      expect(described_class.enabled?).to be_truthy
    end

    it 'returns false when execute_batched_migrations_on_schedule feature flag is disabled' do
      stub_feature_flags(execute_batched_migrations_on_schedule: false)

      expect(described_class.enabled?).to be_falsey
    end

    it 'returns false when disallow_database_ddl_feature_flags feature flag is enabled' do
      stub_feature_flags(disallow_database_ddl_feature_flags: true)

      expect(described_class.enabled?).to be_falsey
    end
  end

  describe '#perform' do
    subject(:worker) { described_class.new }

    context 'when the base model does not exist' do
      before do
        if Gitlab::Database.has_config?(tracking_database)
          skip "because the base model for #{tracking_database} exists"
        end
      end

      it 'does nothing' do
        expect(worker).not_to receive(:queue_migrations_for_execution)

        expect { worker.perform }.not_to raise_error
      end

      it 'logs a message indicating execution is skipped' do
        expect(Sidekiq.logger).to receive(:info) do |payload|
          expect(payload[:class]).to eq(described_class.name)
          expect(payload[:database]).to eq(tracking_database)
          expect(payload[:message]).to match(/skipping migration execution/)
        end

        expect { worker.perform }.not_to raise_error
      end
    end

    context 'when the base model does exist' do
      before do
        unless Gitlab::Database.has_config?(tracking_database)
          skip "because the base model for #{tracking_database} does not exist"
        end
      end

      context 'when the tracking database is shared' do
        before do
          skip_if_database_exists(tracking_database)
        end

        it 'does nothing' do
          expect(worker).not_to receive(:queue_migrations_for_execution)

          worker.perform
        end
      end

      context 'when the tracking database is not shared' do
        before do
          skip_if_shared_database(tracking_database)
        end

        context 'when the execute_batched_migrations_on_schedule feature flag is disabled' do
          before do
            stub_feature_flags(execute_batched_migrations_on_schedule: false)
          end

          it 'does nothing' do
            expect(worker).not_to receive(:queue_migrations_for_execution)

            worker.perform
          end
        end

        context 'when the disallow_database_ddl_feature_flags feature flag is enabled' do
          before do
            stub_feature_flags(disallow_database_ddl_feature_flags: true)
          end

          it 'does nothing' do
            expect(worker).not_to receive(:queue_migrations_for_execution)

            worker.perform
          end
        end

        context 'when the execute_batched_migrations_on_schedule feature flag is enabled' do
          let(:base_model) { Gitlab::Database.database_base_models[tracking_database] }
          let(:connection) { base_model.connection }

          before do
            stub_feature_flags(execute_batched_migrations_on_schedule: true)
          end

          context 'when database config is shared' do
            it 'does nothing' do
              expect(Gitlab::Database).to receive(:db_config_share_with)
                .with(base_model.connection_db_config).and_return('main')

              expect(worker).not_to receive(:queue_migrations_for_execution)

              worker.perform
            end
          end

          context 'when no active migrations exist' do
            it 'does nothing' do
              allow(Gitlab::Database::BackgroundMigration::BatchedMigration)
                .to receive(:active_migrations_distinct_on_table)
                .with(connection: connection, limit: worker.execution_worker_class.max_running_jobs)
                .and_return([])

              expect(worker).not_to receive(:queue_migrations_for_execution)

              worker.perform
            end
          end

          context 'when active migrations exist' do
            let(:job_interval) { 5.minutes }
            let(:lease_timeout) { 15.minutes }
            let(:lease_key) { described_class.name.demodulize.underscore }
            let(:migration_id) { 123 }
            let(:migration) do
              build(
                :batched_background_migration, :active,
                id: migration_id, interval: job_interval, table_name: table_name
              )
            end

            let(:execution_worker_class) do
              case tracking_database
              when :main
                Database::BatchedBackgroundMigration::MainExecutionWorker
              when :ci
                Database::BatchedBackgroundMigration::CiExecutionWorker
              end
            end

            it 'delegetes the execution to ExecutionWorker' do
              expect(Gitlab::Database::BackgroundMigration::BatchedMigration)
                .to receive(:active_migrations_distinct_on_table).with(
                  connection: base_model.connection,
                  limit: execution_worker_class.max_running_jobs
                ).and_return([migration])

              expected_arguments = [
                [tracking_database.to_s, migration_id]
              ]

              expect(execution_worker_class).to receive(:perform_with_capacity).with(expected_arguments)

              worker.perform
            end
          end
        end
      end
    end
  end

  describe 'executing an entire migration', :freeze_time, :sidekiq_inline,
    if: Gitlab::Database.has_database?(tracking_database) do
      include Gitlab::Database::DynamicModelHelpers
      include Database::DatabaseHelpers

      let(:migration_class) do
        Class.new(Gitlab::BackgroundMigration::BatchedMigrationJob) do
          job_arguments :matching_status
          operation_name :update_all
          feature_category :code_review_workflow

          def perform
            each_sub_batch(
              batching_scope: -> (relation) { relation.where(status: matching_status) }
            ) do |sub_batch|
              sub_batch.update_all(some_column: 0)
            end
          end
        end
      end

      let(:gitlab_schema) { "gitlab_#{tracking_database}" }
      let!(:migration) do
        create(
          :batched_background_migration,
          :active,
          table_name: new_table_name,
          column_name: :id,
          max_value: migration_records,
          batch_size: batch_size,
          sub_batch_size: sub_batch_size,
          job_class_name: 'ExampleDataMigration',
          job_arguments: [1],
          gitlab_schema: gitlab_schema
        )
      end

      let(:base_model) { Gitlab::Database.database_base_models[tracking_database] }
      let(:new_table_name) { '_test_example_data' }
      let(:batch_size) { 5 }
      let(:sub_batch_size) { 2 }
      let(:number_of_batches) { 10 }
      let(:migration_records) { batch_size * number_of_batches }

      let(:connection) { Gitlab::Database.database_base_models[tracking_database].connection }
      let(:example_data) { define_batchable_model(new_table_name, connection: connection) }

      around do |example|
        Gitlab::Database::SharedModel.using_connection(connection) do
          example.run
        end
      end

      before do
        stub_feature_flags(execute_batched_migrations_on_schedule: true)

        # Create example table populated with test data to migrate.
        #
        # Test data should have two records that won't be updated:
        #   - one record beyond the migration's range
        #   - one record that doesn't match the migration job's batch condition
        connection.execute(<<~SQL)
        CREATE TABLE #{new_table_name} (
          id integer primary key,
          some_column integer,
          status smallint);

        INSERT INTO #{new_table_name} (id, some_column, status)
        SELECT generate_series, generate_series, 1
        FROM generate_series(1, #{migration_records + 1});

        UPDATE #{new_table_name}
          SET status = 0
        WHERE some_column = #{migration_records - 5};
        SQL

        stub_const('Gitlab::BackgroundMigration::ExampleDataMigration', migration_class)
      end

      subject(:full_migration_run) do
        # process all batches, then do an extra execution to mark the job as finished
        (number_of_batches + 1).times do
          described_class.new.perform

          travel_to((migration.interval + described_class::INTERVAL_VARIANCE).seconds.from_now)
        end
      end

      it 'marks the migration record as finished' do
        expect { full_migration_run }.to change { migration.reload.status }.from(1).to(3) # active -> finished
      end

      it 'creates job records for each processed batch', :aggregate_failures do
        expect { full_migration_run }.to change { migration.reload.batched_jobs.count }.from(0)

        final_min_value = migration.batched_jobs.order(id: :asc).reduce(1) do |next_min_value, batched_job|
          expect(batched_job.min_value).to eq(next_min_value)

          batched_job.max_value + 1
        end

        final_max_value = final_min_value - 1
        expect(final_max_value).to eq(migration_records)
      end

      it 'marks all job records as succeeded', :aggregate_failures do
        expect { full_migration_run }.to change { migration.reload.batched_jobs.count }.from(0)

        expect(migration.batched_jobs).to all(be_succeeded)
      end

      it 'updates matching records in the range', :aggregate_failures do
        expect { full_migration_run }
          .to change { example_data.where('status = 1 AND some_column <> 0').count }
          .from(migration_records).to(1)

        record_outside_range = example_data.last

        expect(record_outside_range.status).to eq(1)
        expect(record_outside_range.some_column).not_to eq(0)
      end

      it 'does not update non-matching records in the range' do
        expect { full_migration_run }.not_to change { example_data.where('status <> 1 AND some_column <> 0').count }
      end

      context 'health status' do
        subject(:migration_run) { described_class.new.perform }

        it 'puts migration on hold when there is autovaccum activity on related tables' do
          swapout_view_for_table(:postgres_autovacuum_activity, connection: connection)
          create(
            :postgres_autovacuum_activity,
            table: migration.table_name,
            table_identifier: "public.#{migration.table_name}"
          )

          expect { migration_run }.to change { migration.reload.on_hold? }.from(false).to(true)
        end

        it 'puts migration on hold when the pending WAL count is above the limit' do
          sql = Gitlab::Database::HealthStatus::Indicators::WriteAheadLog::PENDING_WAL_COUNT_SQL
          limit = Gitlab::Database::HealthStatus::Indicators::WriteAheadLog::LIMIT

          expect(connection).to receive(:execute).with(sql).and_return([{ 'pending_wal_count' => limit + 1 }])

          expect { migration_run }.to change { migration.reload.on_hold? }.from(false).to(true)
        end
      end
    end
end