#pragma once

#include "envoy/server/factory_context.h"

#include "envoy/upstream/upstream.h"

#include "absl/container/flat_hash_map.h"

namespace Envoy {

namespace Extensions {

namespace Common {

namespace DynamicForwardProxy {

class DfpLb {

public:

  virtual Upstream::HostConstSharedPtr findHostByName(const std::string& host) const PURE;

};

class DfpCluster {

public:

  /**

   * @return the cluster enabled subCluster configuration or not.

   */

  virtual bool enableSubCluster() const PURE;

  /**

   * Create a full cluster config for the cluster_name, with the specified host and port.

   * @return true and nullptr when the subCluster with the specified cluster_name already

   *         created, or true and the created cluster config when it not exists and not

   *         reach the limitation of max_sub_clusters, otherwise, return false and nullptr.

   */

  virtual std::pair<bool, absl::optional<envoy::config::cluster::v3::Cluster>>

  createSubClusterConfig(const std::string& cluster_name, const std::string& host,

                         const int port) PURE;

  /**

   * Update the last used time of the subCluster with the specified cluster_name.

   * @return true if the subCluster is existing.

   */

  virtual bool touch(const std::string& cluster_name) PURE;

};

using DfpClusterSharedPtr = std::shared_ptr<DfpCluster>;

using DfpClusterWeakPtr = std::weak_ptr<DfpCluster>;

class DFPClusterStore : public Singleton::Instance {

public:

  // Load the dynamic forward proxy cluster from this store.

  DfpClusterSharedPtr load(std::string cluster_name);

  // Save the dynamic forward proxy cluster into this store.

  void save(const std::string cluster_name, DfpClusterSharedPtr cluster);

  // Remove the dynamic forward proxy cluster from this store.

  void remove(std::string cluster_name);

private:

  using ClusterMapType = absl::flat_hash_map<std::string, DfpClusterWeakPtr>;

  struct ClusterStoreType {

    ClusterMapType map_ ABSL_GUARDED_BY(mutex_);

    absl::Mutex mutex_;

  };

};

using DFPClusterStoreSharedPtr = std::shared_ptr<DFPClusterStore>;

class DFPClusterStoreFactory {

public:

  DFPClusterStoreFactory(Singleton::Manager& singleton_manager)

  DFPClusterStoreSharedPtr get();

private:

  Singleton::Manager& singleton_manager_;

};

} // namespace DynamicForwardProxy

} // namespace Common

} // namespace Extensions

} // namespace Envoy