#include "source/common/router/vhds.h"

#include <chrono>

#include <cstdint>

#include <memory>

#include <string>

#include "envoy/config/core/v3/config_source.pb.h"

#include "envoy/config/subscription.h"

#include "envoy/service/discovery/v3/discovery.pb.h"

#include "source/common/common/assert.h"

#include "source/common/common/fmt.h"

#include "source/common/config/api_version.h"

#include "source/common/config/utility.h"

#include "source/common/protobuf/utility.h"

#include "source/common/router/config_impl.h"

namespace Envoy {

namespace Router {

// Implements callbacks to handle DeltaDiscovery protocol for VirtualHostDiscoveryService

VhdsSubscription::VhdsSubscription(RouteConfigUpdatePtr& config_update_info,

                                   Server::Configuration::ServerFactoryContext& factory_context,

                                   const std::string& stat_prefix,

                                   Rds::RouteConfigProvider* route_config_provider)

    : Envoy::Config::SubscriptionBase<envoy::config::route::v3::VirtualHost>(

          factory_context.messageValidationContext().dynamicValidationVisitor(), "name"),

      config_update_info_(config_update_info),

      scope_(factory_context.scope().createScope(

          stat_prefix + "vhds." + config_update_info_->protobufConfigurationCast().name() + ".")),

      stats_({ALL_VHDS_STATS(POOL_COUNTER(*scope_))}),

      init_target_(fmt::format("VhdsConfigSubscription {}",

                               config_update_info_->protobufConfigurationCast().name()),

                   [this]() {

                     subscription_->start(

                         {config_update_info_->protobufConfigurationCast().name()});

                   }),

      route_config_provider_(route_config_provider) {

  const auto& config_source = config_update_info_->protobufConfigurationCast()

                                  .vhds()

                                  .config_source()

                                  .api_config_source()

                                  .api_type();

  if (config_source != envoy::config::core::v3::ApiConfigSource::DELTA_GRPC) {

    throwEnvoyExceptionOrPanic("vhds: only 'DELTA_GRPC' is supported as an api_type.");

  }

  const auto resource_name = getResourceName();

  Envoy::Config::SubscriptionOptions options;

  options.use_namespace_matching_ = true;

  subscription_ =

      factory_context.clusterManager().subscriptionFactory().subscriptionFromConfigSource(

          config_update_info_->protobufConfigurationCast().vhds().config_source(),

          Grpc::Common::typeUrl(resource_name), *scope_, *this, resource_decoder_, options);

}

void VhdsSubscription::updateOnDemand(const std::string& with_route_config_name_prefix) {

  subscription_->requestOnDemandUpdate({with_route_config_name_prefix});

}

void VhdsSubscription::onConfigUpdateFailed(Envoy::Config::ConfigUpdateFailureReason reason,

                                            const EnvoyException*) {

  ASSERT(Envoy::Config::ConfigUpdateFailureReason::ConnectionFailure != reason);

  // We need to allow server startup to continue, even if we have a bad

  // config.

  init_target_.ready();

}

absl::Status VhdsSubscription::onConfigUpdate(

    const std::vector<Envoy::Config::DecodedResourceRef>& added_resources,

    const Protobuf::RepeatedPtrField<std::string>& removed_resources,

    const std::string& version_info) {

  RouteConfigUpdateReceiver::VirtualHostRefVector added_vhosts;

  std::set<std::string> added_resource_ids;

  for (const auto& resource : added_resources) {

    added_resource_ids.emplace(resource.get().name());

    std::copy(resource.get().aliases().begin(), resource.get().aliases().end(),

              std::inserter(added_resource_ids, added_resource_ids.end()));

    // the management server returns empty resources (they contain no virtual hosts in this case)

    // for aliases that it couldn't resolve.

    if (!resource.get().hasResource()) {

      continue;

    }

    added_vhosts.emplace_back(

        dynamic_cast<const envoy::config::route::v3::VirtualHost&>(resource.get().resource()));

  }

  if (config_update_info_->onVhdsUpdate(added_vhosts, added_resource_ids, removed_resources,

                                        version_info)) {

    stats_.config_reload_.inc();

    ENVOY_LOG(debug, "vhds: loading new configuration: config_name={} hash={}",

              config_update_info_->protobufConfigurationCast().name(),

              config_update_info_->configHash());

    if (route_config_provider_ != nullptr) {

      THROW_IF_NOT_OK(route_config_provider_->onConfigUpdate());

    }

  }

  init_target_.ready();

  return absl::OkStatus();

}

} // namespace Router

} // namespace Envoy