#pragma once

#include <memory>

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

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

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

#include "envoy/config/eds_resources_cache.h"

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

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

#include "envoy/config/subscription.h"

#include "envoy/config/subscription_factory.h"

#include "envoy/local_info/local_info.h"

#include "envoy/registry/registry.h"

#include "envoy/secret/secret_manager.h"

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

#include "envoy/stats/scope.h"

#include "envoy/upstream/locality.h"

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

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

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

#include "source/extensions/clusters/eds/leds.h"

namespace Envoy {

namespace Upstream {

/**

 * Cluster implementation that reads host information from the Endpoint Discovery Service.

 */

class EdsClusterImpl

    : public BaseDynamicClusterImpl,

      Envoy::Config::SubscriptionBase<envoy::config::endpoint::v3::ClusterLoadAssignment>,

      private Config::EdsResourceRemovalCallback {

public:

  static absl::StatusOr<std::unique_ptr<EdsClusterImpl>>

  create(const envoy::config::cluster::v3::Cluster& cluster,

         ClusterFactoryContext& cluster_context);

  ~EdsClusterImpl() override;

  // Upstream::Cluster

  InitializePhase initializePhase() const override { return initialize_phase_; }

protected:

  EdsClusterImpl(const envoy::config::cluster::v3::Cluster& cluster,

                 ClusterFactoryContext& cluster_context, absl::Status& creation_status);

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;

  using LocalityWeightsMap = absl::node_hash_map<envoy::config::core::v3::Locality, uint32_t,

                                                 LocalityHash, LocalityEqualTo>;

  bool updateHostsPerLocality(const uint32_t priority, bool weighted_priority_health,

                              const uint32_t overprovisioning_factor, const HostVector& new_hosts,

                              LocalityWeightsMap& locality_weights_map,

                              LocalityWeightsMap& new_locality_weights_map,

                              PriorityStateManager& priority_state_manager,

                              const HostMap& all_hosts,

                              const absl::flat_hash_set<std::string>& all_new_hosts);

  bool validateUpdateSize(int num_resources);

  const std::string& edsServiceName() const {

    const std::string& name = info_->edsServiceName();

    return !name.empty() ? name : info_->name();

  }

  // Updates the internal data structures with a given cluster load assignment.

  void update(const envoy::config::endpoint::v3::ClusterLoadAssignment& cluster_load_assignment);

  // EdsResourceRemovalCallback

  void onCachedResourceRemoved(absl::string_view resource_name) override;

  // ClusterImplBase

  void reloadHealthyHostsHelper(const HostSharedPtr& host) override;

  void startPreInit() override;

  void onAssignmentTimeout();

  // Returns true iff all the LEDS based localities were updated.

  bool validateAllLedsUpdated() const;

  class BatchUpdateHelper : public PrioritySet::BatchUpdateCb {

  public:

    BatchUpdateHelper(

        EdsClusterImpl& parent,

        const envoy::config::endpoint::v3::ClusterLoadAssignment& cluster_load_assignment)

        : parent_(parent), cluster_load_assignment_(cluster_load_assignment) {}

    // Upstream::PrioritySet::BatchUpdateCb

    void batchUpdate(PrioritySet::HostUpdateCb& host_update_cb) override;

  private:

    void updateLocalityEndpoints(

        const envoy::config::endpoint::v3::LbEndpoint& lb_endpoint,

        const envoy::config::endpoint::v3::LocalityLbEndpoints& locality_lb_endpoint,

        PriorityStateManager& priority_state_manager,

        absl::flat_hash_set<std::string>& all_new_hosts);

    EdsClusterImpl& parent_;

    const envoy::config::endpoint::v3::ClusterLoadAssignment& cluster_load_assignment_;

  };

  Config::SubscriptionPtr subscription_;

  const LocalInfo::LocalInfo& local_info_;

  std::vector<LocalityWeightsMap> locality_weights_map_;

  Event::TimerPtr assignment_timeout_;

  InitializePhase initialize_phase_;

  using LedsConfigSet = absl::flat_hash_set<envoy::config::endpoint::v3::LedsClusterLocalityConfig,

                                            MessageUtil, MessageUtil>;

  using LedsConfigMap = absl::flat_hash_map<envoy::config::endpoint::v3::LedsClusterLocalityConfig,

                                            LedsSubscriptionPtr, MessageUtil, MessageUtil>;

  // Maps between a LEDS configuration (ConfigSource + collection name) to the locality endpoints

  // data.

  LedsConfigMap leds_localities_;

  // TODO(adisuissa): Avoid saving the entire cluster load assignment, only the

  // relevant parts of the config for each locality. Note that this field must

  // be set when LEDS is used.

  std::unique_ptr<envoy::config::endpoint::v3::ClusterLoadAssignment> cluster_load_assignment_;

  // An optional cache for the EDS resources.

  // Upon a (warming) timeout, a cached resource will be used.

  Config::EdsResourcesCacheOptRef eds_resources_cache_;

  // Tracks whether a cached resource is used as the current EDS resource.

  bool using_cached_resource_{false};

};

using EdsClusterImplSharedPtr = std::shared_ptr<EdsClusterImpl>;

class EdsClusterFactory : public ClusterFactoryImplBase {

public:

  EdsClusterFactory() : ClusterFactoryImplBase("envoy.cluster.eds") {}

private:

  absl::StatusOr<std::pair<ClusterImplBaseSharedPtr, ThreadAwareLoadBalancerPtr>>

  createClusterImpl(const envoy::config::cluster::v3::Cluster& cluster,

                    ClusterFactoryContext& context) override;

};

DECLARE_FACTORY(EdsClusterFactory);

} // namespace Upstream

} // namespace Envoy