# frozen_string_literal: true

require 'spec_helper'

RSpec.describe Gitlab::Database::LoadBalancing::Configuration do
  let(:configuration_hash) { {} }
  let(:db_config) { ActiveRecord::DatabaseConfigurations::HashConfig.new('test', 'ci', configuration_hash) }
  let(:model) { double(:model, connection_db_config: db_config) }

  describe '.for_model' do
    context 'when load balancing is not configured' do
      it 'uses the default settings' do
        config = described_class.for_model(model)

        expect(config.hosts).to eq([])
        expect(config.max_replication_difference).to eq(8.megabytes)
        expect(config.max_replication_lag_time).to eq(60.0)
        expect(config.replica_check_interval).to eq(60.0)
        expect(config.service_discovery).to eq(
          nameserver: 'localhost',
          port: 8600,
          record: nil,
          record_type: 'A',
          interval: 60,
          disconnect_timeout: 120,
          use_tcp: false
        )
        expect(config.pool_size).to eq(Gitlab::Database.default_pool_size)
      end
    end

    context 'when load balancing is configured' do
      let(:configuration_hash) do
        {
          pool: 4,
          load_balancing: {
            max_replication_difference: 1,
            max_replication_lag_time: 2,
            replica_check_interval: 3,
            hosts: %w[foo bar],
            discover: {
              'record' => 'foo.example.com'
            }
          }
        }
      end

      it 'uses the custom configuration settings' do
        config = described_class.for_model(model)

        expect(config.hosts).to eq(%w[foo bar])
        expect(config.max_replication_difference).to eq(1)
        expect(config.max_replication_lag_time).to eq(2.0)
        expect(config.replica_check_interval).to eq(3.0)
        expect(config.service_discovery).to eq(
          nameserver: 'localhost',
          port: 8600,
          record: 'foo.example.com',
          record_type: 'A',
          interval: 60,
          disconnect_timeout: 120,
          use_tcp: false
        )
        expect(config.pool_size).to eq(4)
      end
    end

    context 'when the load balancing configuration uses strings as the keys' do
      let(:configuration_hash) do
        {
          pool: 4,
          load_balancing: {
            'max_replication_difference' => 1,
            'max_replication_lag_time' => 2,
            'replica_check_interval' => 3,
            'hosts' => %w[foo bar],
            'discover' => {
              'record' => 'foo.example.com'
            }
          }
        }
      end

      it 'uses the custom configuration settings' do
        config = described_class.for_model(model)

        expect(config.hosts).to eq(%w[foo bar])
        expect(config.max_replication_difference).to eq(1)
        expect(config.max_replication_lag_time).to eq(2.0)
        expect(config.replica_check_interval).to eq(3.0)
        expect(config.service_discovery).to eq(
          nameserver: 'localhost',
          port: 8600,
          record: 'foo.example.com',
          record_type: 'A',
          interval: 60,
          disconnect_timeout: 120,
          use_tcp: false
        )
        expect(config.pool_size).to eq(4)
      end
    end

    it 'calls reuse_primary_connection!' do
      expect_next_instance_of(described_class) do |subject|
        expect(subject).to receive(:reuse_primary_connection!).and_call_original
      end

      described_class.for_model(model)
    end
  end

  describe '#load_balancing_enabled?' do
    it 'returns false when running inside a Rake task' do
      config = described_class.new(ActiveRecord::Base, %w[foo bar])

      allow(Gitlab::Runtime).to receive(:rake?).and_return(true)

      expect(config.load_balancing_enabled?).to eq(false)
    end

    it 'returns true when hosts are configured' do
      config = described_class.new(ActiveRecord::Base, %w[foo bar])

      expect(config.load_balancing_enabled?).to eq(true)
    end

    it 'returns true when a service discovery record is configured' do
      config = described_class.new(ActiveRecord::Base)
      config.service_discovery[:record] = 'foo'

      expect(config.load_balancing_enabled?).to eq(true)
    end

    it 'returns false when no hosts are configured and service discovery is disabled' do
      config = described_class.new(ActiveRecord::Base)

      expect(config.load_balancing_enabled?).to eq(false)
    end
  end

  describe '#service_discovery_enabled?' do
    it 'returns false when running inside a Rake task' do
      allow(Gitlab::Runtime).to receive(:rake?).and_return(true)

      config = described_class.new(ActiveRecord::Base)
      config.service_discovery[:record] = 'foo'

      expect(config.service_discovery_enabled?).to eq(false)
    end

    it 'returns true when a record is configured' do
      config = described_class.new(ActiveRecord::Base)
      config.service_discovery[:record] = 'foo'

      expect(config.service_discovery_enabled?).to eq(true)
    end

    it 'returns false when no record is configured' do
      config = described_class.new(ActiveRecord::Base)

      expect(config.service_discovery_enabled?).to eq(false)
    end
  end

  describe '#pool_size' do
    context 'when a custom pool size is used' do
      let(:configuration_hash) { { pool: 4 } }

      it 'always reads the value from the model configuration' do
        config = described_class.new(model)

        expect(config.pool_size).to eq(4)

        # We can't modify `configuration_hash` as it's only used to populate the
        # internal hash used by ActiveRecord; instead of it being used as-is.
        allow(model.connection_db_config)
          .to receive(:configuration_hash)
          .and_return({ pool: 42 })

        expect(config.pool_size).to eq(42)
      end
    end

    context 'when the pool size is nil' do
      let(:configuration_hash) { {} }

      it 'returns the default pool size' do
        config = described_class.new(model)

        expect(config.pool_size).to eq(Gitlab::Database.default_pool_size)
      end
    end
  end

  describe '#db_config_name' do
    let(:config) { described_class.new(model) }

    subject { config.db_config_name }

    it 'returns connection name as symbol' do
      is_expected.to eq(:ci)
    end
  end

  describe '#replica_db_config' do
    let(:model) { double(:model, connection_db_config: db_config, connection_specification_name: 'Ci::ApplicationRecord') }
    let(:config) { described_class.for_model(model) }

    it 'returns exactly db_config' do
      expect(config.replica_db_config).to eq(db_config)
    end

    context 'when GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci=main' do
      it 'does not change replica_db_config' do
        stub_env('GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci', 'main')

        expect(config.replica_db_config).to eq(db_config)
      end
    end
  end

  describe 'reuse_primary_connection!' do
    let(:model) { double(:model, connection_db_config: db_config, connection_specification_name: 'Ci::ApplicationRecord') }
    let(:config) { described_class.for_model(model) }

    context 'when GITLAB_LOAD_BALANCING_REUSE_PRIMARY_* not configured' do
      it 'the primary connection uses default specification' do
        stub_env('GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci', nil)

        expect(config.primary_connection_specification_name).to eq('Ci::ApplicationRecord')
      end
    end

    context 'when GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci=main' do
      it 'the primary connection uses main connection' do
        stub_env('GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci', 'main')

        expect(config.primary_connection_specification_name).to eq('ActiveRecord::Base')
      end
    end

    context 'when GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci=unknown' do
      it 'raises exception' do
        stub_env('GITLAB_LOAD_BALANCING_REUSE_PRIMARY_ci', 'unknown')

        expect { config.reuse_primary_connection! }.to raise_error /Invalid value for/
      end
    end
  end
end