#pragma once

#include <string>

#include <vector>

#include "envoy/config/cluster/v3/cluster.pb.h"

#include "envoy/config/cluster/v3/cluster.pb.validate.h"

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

#include "envoy/config/subscription.h"

#include "envoy/protobuf/message_validator.h"

#include "envoy/server/factory_context.h"

#include "envoy/stats/scope.h"

#include "envoy/upstream/cluster_manager.h"

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

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

#include "source/common/upstream/cds_api_helper.h"

namespace Envoy {

namespace Upstream {

enum class StartStatus {

  // No initial fetch started.

  NotStarted,

  // Initial fetch started.

  Started,

  // Initial fetch arrived.

  InitialFetchDone,

};

/**

 * ODCDS API implementation that fetches via Subscription.

 */

class OdCdsApiImpl : public OdCdsApi,

                     Envoy::Config::SubscriptionBase<envoy::config::cluster::v3::Cluster>,

                     Logger::Loggable<Logger::Id::upstream> {

public:

  static absl::StatusOr<OdCdsApiSharedPtr>

  create(const envoy::config::core::v3::ConfigSource& odcds_config,

         OptRef<xds::core::v3::ResourceLocator> odcds_resources_locator,

         Config::XdsManager& xds_manager, ClusterManager& cm, MissingClusterNotifier& notifier,

         Stats::Scope& scope, ProtobufMessage::ValidationVisitor& validation_visitor,

         Server::Configuration::ServerFactoryContext& server_factory_context);

  // Upstream::OdCdsApi

  void updateOnDemand(std::string cluster_name) override;

private:

  // Config::SubscriptionCallbacks

  absl::Status onConfigUpdate(const std::vector<Config::DecodedResourceRef>& resources,

                              const std::string& version_info) override;

  absl::Status onConfigUpdate(const std::vector<Config::DecodedResourceRef>& added_resources,

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

                              const std::string& system_version_info) override;

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

                            const EnvoyException* e) override;

  OdCdsApiImpl(const envoy::config::core::v3::ConfigSource& odcds_config,

               OptRef<xds::core::v3::ResourceLocator> odcds_resources_locator,

               Config::XdsManager& xds_manager, ClusterManager& cm,

               MissingClusterNotifier& notifier, Stats::Scope& scope,

               ProtobufMessage::ValidationVisitor& validation_visitor,

               absl::Status& creation_status);

  void sendAwaiting();

  CdsApiHelper helper_;

  MissingClusterNotifier& notifier_;

  Stats::ScopeSharedPtr scope_;

  StartStatus status_{StartStatus::NotStarted};

  absl::flat_hash_set<std::string> awaiting_names_;

  Config::SubscriptionPtr subscription_;

};

/**

 * ODCDS API implementation that fetches via Subscription for xDS-TP based

 * configs and resources.

 */

class XdstpOdCdsApiImpl : public OdCdsApi {

public:

  static absl::StatusOr<OdCdsApiSharedPtr>

  create(const envoy::config::core::v3::ConfigSource&, OptRef<xds::core::v3::ResourceLocator>,

         Config::XdsManager& xds_manager, ClusterManager& cm, MissingClusterNotifier& notifier,

         Stats::Scope& scope, ProtobufMessage::ValidationVisitor& validation_visitor,

         Server::Configuration::ServerFactoryContext& server_factory_context);

  // Upstream::OdCdsApi

  void updateOnDemand(std::string cluster_name) override;

private:

  class XdstpOdcdsSubscriptionsManager;

  using XdstpOdcdsSubscriptionsManagerSharedPtr = std::shared_ptr<XdstpOdcdsSubscriptionsManager>;

  XdstpOdCdsApiImpl(Config::XdsManager& xds_manager, ClusterManager& cm,

                    MissingClusterNotifier& notifier, Stats::Scope& scope,

                    Server::Configuration::ServerFactoryContext& server_context, bool old_ads,

                    ProtobufMessage::ValidationVisitor& validation_visitor,

                    absl::Status& creation_status);

  // Fetches, and potentially creates, the singleton subscriptions manager.

  // The arguments will be passed to the subscriptions manager's constructor, if

  // it is the first time it is initialized.

  static XdstpOdcdsSubscriptionsManagerSharedPtr

  subscriptionsManager(Server::Configuration::ServerFactoryContext& context,

                       Config::XdsManager& xds_manager, ClusterManager& cm,

                       MissingClusterNotifier& notifier, Stats::Scope& scope,

                       ProtobufMessage::ValidationVisitor& validation_visitor);

  // A singleton through which all subscriptions will be processed.

  XdstpOdcdsSubscriptionsManagerSharedPtr subscriptions_manager_;

  const bool old_ads_;

};

} // namespace Upstream

} // namespace Envoy