#include "envoy/config/cluster/v3/cluster.pb.h"
#include "envoy/grpc/status.h"
#include "envoy/service/discovery/v3/discovery.pb.h"
#include "envoy/stats/scope.h"

#include "common/config/protobuf_link_hacks.h"
#include "common/protobuf/protobuf.h"
#include "common/protobuf/utility.h"

#include "test/common/grpc/grpc_client_integration.h"
#include "test/integration/http_integration.h"
#include "test/integration/utility.h"
#include "test/test_common/network_utility.h"
#include "test/test_common/resources.h"
#include "test/test_common/simulated_time_system.h"
#include "test/test_common/utility.h"

#include "absl/synchronization/notification.h"
#include "gtest/gtest.h"

using testing::AssertionResult;

namespace Envoy {
namespace {

const char ClusterName1[] = "cluster_1";
const char ClusterName2[] = "cluster_2";
const int UpstreamIndex1 = 1;
const int UpstreamIndex2 = 2;

class CdsIntegrationTest : public Grpc::DeltaSotwIntegrationParamTest, public HttpIntegrationTest {
public:
  CdsIntegrationTest()
      : HttpIntegrationTest(Http::CodecClient::Type::HTTP2, ipVersion(),
                            ConfigHelper::discoveredClustersBootstrap(
                                sotwOrDelta() == Grpc::SotwOrDelta::Sotw ? "GRPC" : "DELTA_GRPC")) {
    use_lds_ = false;
    sotw_or_delta_ = sotwOrDelta();
  }

  void TearDown() override {
    if (!test_skipped_) {
      cleanUpXdsConnection();
    }
  }

  // Overridden to insert this stuff into the initialize() at the very beginning of
  // HttpIntegrationTest::testRouterHeaderOnlyRequestAndResponse().
  void initialize() override {
    use_lds_ = false;
    test_skipped_ = false;
    // Controls how many addFakeUpstream() will happen in
    // BaseIntegrationTest::createUpstreams() (which is part of initialize()).
    // Make sure this number matches the size of the 'clusters' repeated field in the bootstrap
    // config that you use!
    setUpstreamCount(1);                                  // the CDS cluster
    setUpstreamProtocol(FakeHttpConnection::Type::HTTP2); // CDS uses gRPC uses HTTP2.

    // HttpIntegrationTest::initialize() does many things:
    // 1) It appends to fake_upstreams_ as many as you asked for via setUpstreamCount().
    // 2) It updates your bootstrap config with the ports your fake upstreams are actually listening
    //    on (since you're supposed to leave them as 0).
    // 3) It creates and starts an IntegrationTestServer - the thing that wraps the almost-actual
    //    Envoy used in the tests.
    // 4) Bringing up the server usually entails waiting to ensure that any listeners specified in
    //    the bootstrap config have come up, and registering them in a port map (see lookupPort()).
    //    However, this test needs to defer all of that to later.
    defer_listener_finalization_ = true;
    HttpIntegrationTest::initialize();

    // Create the regular (i.e. not an xDS server) upstreams. We create them manually here after
    // initialize() because finalize() expects all fake_upstreams_ to correspond to a static
    // cluster in the bootstrap config - which we don't want since we're testing dynamic CDS!
    addFakeUpstream(FakeHttpConnection::Type::HTTP2);
    addFakeUpstream(FakeHttpConnection::Type::HTTP2);
    cluster1_ = ConfigHelper::buildStaticCluster(
        ClusterName1, fake_upstreams_[UpstreamIndex1]->localAddress()->ip()->port(),
        Network::Test::getLoopbackAddressString(ipVersion()));
    cluster2_ = ConfigHelper::buildStaticCluster(
        ClusterName2, fake_upstreams_[UpstreamIndex2]->localAddress()->ip()->port(),
        Network::Test::getLoopbackAddressString(ipVersion()));

    // Let Envoy establish its connection to the CDS server.
    acceptXdsConnection();

    // Do the initial compareDiscoveryRequest / sendDiscoveryResponse for cluster_1.
    EXPECT_TRUE(compareDiscoveryRequest(Config::TypeUrl::get().Cluster, "", {}, {}, {}, true));
    sendDiscoveryResponse<envoy::config::cluster::v3::Cluster>(Config::TypeUrl::get().Cluster,
                                                               {cluster1_}, {cluster1_}, {}, "55");

    // We can continue the test once we're sure that Envoy's ClusterManager has made use of
    // the DiscoveryResponse describing cluster_1 that we sent.
    // 2 because the statically specified CDS server itself counts as a cluster.
    test_server_->waitForGaugeGe("cluster_manager.active_clusters", 2);

    // Wait for our statically specified listener to become ready, and register its port in the
    // test framework's downstream listener port map.
    test_server_->waitUntilListenersReady();
    registerTestServerPorts({"http"});
  }

  // Regression test to catch the code declaring a gRPC service method for {SotW,delta}
  // when the user's bootstrap config asks for the other type.
  void verifyGrpcServiceMethod() {
    EXPECT_TRUE(xds_stream_->waitForHeadersComplete());
    Envoy::Http::LowerCaseString path_string(":path");
    std::string expected_method(sotwOrDelta() == Grpc::SotwOrDelta::Sotw
                                    ? "/envoy.api.v2.ClusterDiscoveryService/StreamClusters"
                                    : "/envoy.api.v2.ClusterDiscoveryService/DeltaClusters");
    EXPECT_EQ(xds_stream_->headers().get(path_string)[0]->value(), expected_method);
  }

  void acceptXdsConnection() {
    AssertionResult result = // xds_connection_ is filled with the new FakeHttpConnection.
        fake_upstreams_[0]->waitForHttpConnection(*dispatcher_, xds_connection_);
    RELEASE_ASSERT(result, result.message());
    result = xds_connection_->waitForNewStream(*dispatcher_, xds_stream_);
    RELEASE_ASSERT(result, result.message());
    xds_stream_->startGrpcStream();
    verifyGrpcServiceMethod();
  }

  envoy::config::cluster::v3::Cluster cluster1_;
  envoy::config::cluster::v3::Cluster cluster2_;
  // True if we decided not to run the test after all.
  bool test_skipped_{true};
};

INSTANTIATE_TEST_SUITE_P(IpVersionsClientTypeDelta, CdsIntegrationTest,
                         DELTA_SOTW_GRPC_CLIENT_INTEGRATION_PARAMS);

// 1) Envoy starts up with no static clusters (other than the CDS-over-gRPC server).
// 2) Envoy is told of a cluster via CDS.
// 3) We send Envoy a request, which we verify is properly proxied to and served by that cluster.
// 4) Envoy is told that cluster is gone.
// 5) We send Envoy a request, which should 503.
// 6) Envoy is told that the cluster is back.
// 7) We send Envoy a request, which we verify is properly proxied to and served by that cluster.
TEST_P(CdsIntegrationTest, CdsClusterUpDownUp) {
  // Calls our initialize(), which includes establishing a listener, route, and cluster.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex1, "/cluster1");
  test_server_->waitForCounterGe("cluster_manager.cluster_added", 1);

  // Tell Envoy that cluster_1 is gone.
  EXPECT_TRUE(compareDiscoveryRequest(Config::TypeUrl::get().Cluster, "55", {}, {}, {}));
  sendDiscoveryResponse<envoy::config::cluster::v3::Cluster>(Config::TypeUrl::get().Cluster, {}, {},
                                                             {ClusterName1}, "42");
  // We can continue the test once we're sure that Envoy's ClusterManager has made use of
  // the DiscoveryResponse that says cluster_1 is gone.
  test_server_->waitForCounterGe("cluster_manager.cluster_removed", 1);

  // Now that cluster_1 is gone, the listener (with its routing to cluster_1) should 503.
  BufferingStreamDecoderPtr response = IntegrationUtil::makeSingleRequest(
      lookupPort("http"), "GET", "/cluster1", "", downstream_protocol_, version_, "foo.com");
  ASSERT_TRUE(response->complete());
  EXPECT_EQ("503", response->headers().getStatusValue());

  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());

  // Tell Envoy that cluster_1 is back.
  EXPECT_TRUE(compareDiscoveryRequest(Config::TypeUrl::get().Cluster, "42", {}, {}, {}));
  sendDiscoveryResponse<envoy::config::cluster::v3::Cluster>(Config::TypeUrl::get().Cluster,
                                                             {cluster1_}, {cluster1_}, {}, "413");

  // We can continue the test once we're sure that Envoy's ClusterManager has made use of
  // the DiscoveryResponse describing cluster_1 that we sent. Again, 2 includes CDS server.
  test_server_->waitForGaugeGe("cluster_manager.active_clusters", 2);

  // Does *not* call our initialize().
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex1, "/cluster1");

  cleanupUpstreamAndDownstream();
}

// Tests adding a cluster, adding another, then removing the first.
TEST_P(CdsIntegrationTest, TwoClusters) {
  // Calls our initialize(), which includes establishing a listener, route, and cluster.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex1, "/cluster1");

  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());

  // Tell Envoy that cluster_2 is here.
  EXPECT_TRUE(compareDiscoveryRequest(Config::TypeUrl::get().Cluster, "55", {}, {}, {}));
  sendDiscoveryResponse<envoy::config::cluster::v3::Cluster>(
      Config::TypeUrl::get().Cluster, {cluster1_, cluster2_}, {cluster2_}, {}, "42");
  // The '3' includes the fake CDS server.
  test_server_->waitForGaugeGe("cluster_manager.active_clusters", 3);

  // A request for cluster_2 should be fine.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex2, "/cluster2");
  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());

  // Tell Envoy that cluster_1 is gone.
  EXPECT_TRUE(compareDiscoveryRequest(Config::TypeUrl::get().Cluster, "42", {}, {}, {}));
  sendDiscoveryResponse<envoy::config::cluster::v3::Cluster>(Config::TypeUrl::get().Cluster,
                                                             {cluster2_}, {}, {ClusterName1}, "43");
  // We can continue the test once we're sure that Envoy's ClusterManager has made use of
  // the DiscoveryResponse that says cluster_1 is gone.
  test_server_->waitForCounterGe("cluster_manager.cluster_removed", 1);

  // Even with cluster_1 gone, a request for cluster_2 should be fine.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex2, "/cluster2");
  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());

  // Tell Envoy that cluster_1 is back.
  EXPECT_TRUE(compareDiscoveryRequest(Config::TypeUrl::get().Cluster, "43", {}, {}, {}));
  sendDiscoveryResponse<envoy::config::cluster::v3::Cluster>(
      Config::TypeUrl::get().Cluster, {cluster1_, cluster2_}, {cluster1_}, {}, "413");

  // We can continue the test once we're sure that Envoy's ClusterManager has made use of
  // the DiscoveryResponse describing cluster_1 that we sent. Again, 3 includes CDS server.
  test_server_->waitForGaugeGe("cluster_manager.active_clusters", 3);

  // Does *not* call our initialize().
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex1, "/cluster1");

  cleanupUpstreamAndDownstream();
}

// Tests that when Envoy's delta xDS stream dis/reconnects, Envoy can inform the server of the
// resources it already has: the reconnected stream need not start with a state-of-the-world update.
TEST_P(CdsIntegrationTest, VersionsRememberedAfterReconnect) {
  SKIP_IF_XDS_IS(Grpc::SotwOrDelta::Sotw);

  // Calls our initialize(), which includes establishing a listener, route, and cluster.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex1, "/cluster1");
  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());

  // Close the connection carrying Envoy's xDS gRPC stream...
  AssertionResult result = xds_connection_->close();
  RELEASE_ASSERT(result, result.message());
  result = xds_connection_->waitForDisconnect();
  RELEASE_ASSERT(result, result.message());
  xds_connection_.reset();
  // ...and reconnect it.
  acceptXdsConnection();

  // Upon reconnecting, the Envoy should tell us its current resource versions.
  API_NO_BOOST(envoy::api::v2::DeltaDiscoveryRequest) request;
  result = xds_stream_->waitForGrpcMessage(*dispatcher_, request);
  RELEASE_ASSERT(result, result.message());
  const auto& initial_resource_versions = request.initial_resource_versions();
  EXPECT_EQ("55", initial_resource_versions.at(std::string(ClusterName1)));
  EXPECT_EQ(1, initial_resource_versions.size());

  // Tell Envoy that cluster_2 is here. This update does *not* need to include cluster_1,
  // which Envoy should already know about despite the disconnect.
  sendDeltaDiscoveryResponse<envoy::config::cluster::v3::Cluster>(Config::TypeUrl::get().Cluster,
                                                                  {cluster2_}, {}, "42");
  // The '3' includes the fake CDS server.
  test_server_->waitForGaugeGe("cluster_manager.active_clusters", 3);

  // A request for cluster_1 should be fine.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex1, "/cluster1");
  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());
  // A request for cluster_2 should be fine.
  testRouterHeaderOnlyRequestAndResponse(nullptr, UpstreamIndex2, "/cluster2");
  cleanupUpstreamAndDownstream();
  ASSERT_TRUE(codec_client_->waitForDisconnect());
}

} // namespace
} // namespace Envoy