#pragma once

#include <string>

#include <vector>

#include "envoy/config/subscription.h"

#include "envoy/config/xds_manager.h"

#include "envoy/upstream/cluster_manager.h"

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

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

namespace Envoy {

namespace Upstream {

/**

 * A named helper class for handling a successful cluster configuration update from Subscription. A

 * name is used mostly for logging to differentiate between different users of the helper class.

 */

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

public:

  CdsApiHelper(ClusterManager& cm, Config::XdsManager& xds_manager, std::string name)

  /**

   * onConfigUpdate handles the addition and removal of clusters by notifying the ClusterManager

   * about the cluster changes. It closely follows the onConfigUpdate API from

   * Config::SubscriptionCallbacks, with the exception of the return value documented below.

   *

   * @param added_resources clusters newly added since the previous fetch.

   * @param removed_resources names of clusters that this fetch instructed to be removed.

   * @param system_version_info aggregate response data "version", for debugging.

   * @return std::pair<uint32_t, std::vector<std::string>> the actual number of added or updated

   * clusters and a list of errors that occurred while updating the clusters.

   */

  std::pair<uint32_t, std::vector<std::string>>

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

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

                 const std::string& system_version_info);

private:

  ClusterManager& cm_;

  Config::XdsManager& xds_manager_;

  const std::string name_;

  std::string system_version_info_;

};

} // namespace Upstream

} // namespace Envoy