require 'spec_helper'

describe Gitlab::EtagCaching::Middleware do
  let(:app) { double(:app) }
  let(:middleware) { described_class.new(app) }
  let(:app_status_code) { 200 }
  let(:if_none_match) { nil }
  let(:enabled_path) { '/gitlab-org/gitlab-ce/noteable/issue/1/notes' }

  context 'when ETag caching is not enabled for current route' do
    let(:path) { '/gitlab-org/gitlab-ce/tree/master/noteable/issue/1/notes' }

    before do
      mock_app_response
    end

    it 'does not add ETag header' do
      _, headers, _ = middleware.call(build_env(path, if_none_match))

      expect(headers['ETag']).to be_nil
    end

    it 'passes status code from app' do
      status, _, _ = middleware.call(build_env(path, if_none_match))

      expect(status).to eq app_status_code
    end
  end

  context 'when there is no ETag in store for given resource' do
    let(:path) { enabled_path }

    before do
      mock_app_response
      mock_value_in_store(nil)
    end

    it 'generates ETag' do
      expect_any_instance_of(Gitlab::EtagCaching::Store)
        .to receive(:touch).and_return('123')

      middleware.call(build_env(path, if_none_match))
    end

    context 'when If-None-Match header was specified' do
      let(:if_none_match) { 'W/"abc"' }

      it 'tracks "etag_caching_key_not_found" event' do
        expect(Gitlab::Metrics).to receive(:add_event)
          .with(:etag_caching_middleware_used)
        expect(Gitlab::Metrics).to receive(:add_event)
          .with(:etag_caching_key_not_found)

        middleware.call(build_env(path, if_none_match))
      end
    end
  end

  context 'when there is ETag in store for given resource' do
    let(:path) { enabled_path }

    before do
      mock_app_response
      mock_value_in_store('123')
    end

    it 'returns this value as header' do
      _, headers, _ = middleware.call(build_env(path, if_none_match))

      expect(headers['ETag']).to eq 'W/"123"'
    end
  end

  context 'when If-None-Match header matches ETag in store' do
    let(:path) { enabled_path }
    let(:if_none_match) { 'W/"123"' }

    before do
      mock_value_in_store('123')
    end

    it 'does not call app' do
      expect(app).not_to receive(:call)

      middleware.call(build_env(path, if_none_match))
    end

    it 'returns status code 304' do
      status, _, _ = middleware.call(build_env(path, if_none_match))

      expect(status).to eq 304
    end

    it 'tracks "etag_caching_cache_hit" event' do
      expect(Gitlab::Metrics).to receive(:add_event)
        .with(:etag_caching_middleware_used)
      expect(Gitlab::Metrics).to receive(:add_event)
        .with(:etag_caching_cache_hit)

      middleware.call(build_env(path, if_none_match))
    end
  end

  context 'when If-None-Match header does not match ETag in store' do
    let(:path) { enabled_path }
    let(:if_none_match) { 'W/"abc"' }

    before do
      mock_value_in_store('123')
    end

    it 'calls app' do
      expect(app).to receive(:call).and_return([app_status_code, {}, ['body']])

      middleware.call(build_env(path, if_none_match))
    end

    it 'tracks "etag_caching_resource_changed" event' do
      mock_app_response

      expect(Gitlab::Metrics).to receive(:add_event)
        .with(:etag_caching_middleware_used)
      expect(Gitlab::Metrics).to receive(:add_event)
        .with(:etag_caching_resource_changed)

      middleware.call(build_env(path, if_none_match))
    end
  end

  context 'when If-None-Match header is not specified' do
    let(:path) { enabled_path }

    before do
      mock_value_in_store('123')
      mock_app_response
    end

    it 'tracks "etag_caching_header_missing" event' do
      expect(Gitlab::Metrics).to receive(:add_event)
        .with(:etag_caching_middleware_used)
      expect(Gitlab::Metrics).to receive(:add_event)
        .with(:etag_caching_header_missing)

      middleware.call(build_env(path, if_none_match))
    end
  end

  def mock_app_response
    allow(app).to receive(:call).and_return([app_status_code, {}, ['body']])
  end

  def mock_value_in_store(value)
    allow_any_instance_of(Gitlab::EtagCaching::Store)
      .to receive(:get).and_return(value)
  end

  def build_env(path, if_none_match)
    {
      'PATH_INFO' => path,
      'HTTP_IF_NONE_MATCH' => if_none_match
    }
  end
end
