#pragma once

#include <memory>

#include "envoy/config/endpoint/v3/endpoint_components.pb.h"

#include "envoy/config/endpoint/v3/endpoint_components.pb.validate.h"

#include "envoy/config/subscription.h"

#include "envoy/local_info/local_info.h"

#include "envoy/stats/scope.h"

#include "envoy/stats/stats_macros.h"

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

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

namespace Envoy {

namespace Upstream {

/**

 * All per-cluster LEDS stats. @see stats_macros.h

 * These will be added to the subscription stats.

 */

#define ALL_LEDS_STATS(COUNTER) COUNTER(update_empty)

/**

 * Struct definition for all per-cluster LEDS stats. @see stats_macros.h

 */

struct LedsStats {

  ALL_LEDS_STATS(GENERATE_COUNTER_STRUCT)

};

/*

 * A single subscription for all LEDS resources of a specific SourceConfig that

 * fetches updates from a Locality Endpoint Discovery Service.

 * Multiple subscriptions with the same LEDS collection name can use a single

 * subscription.

 */

class LedsSubscription

    : private Envoy::Config::SubscriptionBase<envoy::config::endpoint::v3::LbEndpoint>,

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

public:

  using UpdateCb = std::function<void()>;

  using LbEndpointsMap = absl::flat_hash_map<std::string, envoy::config::endpoint::v3::LbEndpoint>;

  LedsSubscription(const envoy::config::endpoint::v3::LedsClusterLocalityConfig& leds_config,

                   const std::string& cluster_name,

                   Server::Configuration::TransportSocketFactoryContext& factory_context,

                   Stats::Scope& stats_scope, const UpdateCb& callback);

  // Returns the map between registered LEDS resource names and their endpoints data.

  const LbEndpointsMap& getEndpointsMap() const { return endpoints_map_; }

  // Returns true iff the endpoints were updated.

  bool isUpdated() const { return initial_update_attempt_complete_; }

private:

  // Config::SubscriptionCallbacks

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

                              const std::string&) override {

    return absl::OkStatus();

  }

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

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

                              const std::string&) override;

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

                            const EnvoyException* e) override;

  const LocalInfo::LocalInfo& local_info_;

  const std::string cluster_name_;

  // LEDS stats scope must outlive the subscription.

  Stats::ScopeSharedPtr stats_scope_;

  LedsStats stats_;

  // A map between a LEDS resource name to the LbEndpoint data.

  LbEndpointsMap endpoints_map_;

  // A callback function activated after an update is received (either successful or

  // unsuccessful).

  const UpdateCb callback_;

  // Once the endpoints of the locality are updated, it is considered active.

  bool initial_update_attempt_complete_{false};

  Config::SubscriptionPtr subscription_;

};

using LedsSubscriptionPtr = std::unique_ptr<LedsSubscription>;

} // namespace Upstream

} // namespace Envoy