//
// Copyright 2022 gRPC authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#ifndef GRPCPP_EXT_ORCA_SERVICE_H
#define GRPCPP_EXT_ORCA_SERVICE_H

#include <map>
#include <string>

#include "absl/time/time.h"
#include "absl/types/optional.h"

#include <grpcpp/impl/codegen/server_callback.h>
#include <grpcpp/impl/codegen/service_type.h>
#include <grpcpp/impl/codegen/sync.h>
#include <grpcpp/server_builder.h>
#include <grpcpp/support/slice.h>

namespace grpc {
namespace experimental {

// RPC service implementation for supplying out-of-band backend
// utilization metrics to clients.
class OrcaService : public Service {
 public:
  struct Options {
    // Minimum report interval.  If a client requests an interval lower
    // than this value, this value will be used instead.
    absl::Duration min_report_duration = absl::Seconds(30);

    Options() = default;
    Options& set_min_report_duration(absl::Duration duration) {
      min_report_duration = duration;
      return *this;
    }
  };

  explicit OrcaService(Options options);

  // Sets or removes the CPU utilization value to be reported to clients.
  void SetCpuUtilization(double cpu_utilization);
  void DeleteCpuUtilization();

  // Sets of removes the memory utilization value to be reported to clients.
  void SetMemoryUtilization(double memory_utilization);
  void DeleteMemoryUtilization();

  // Sets or removed named utilization values to be reported to clients.
  void SetNamedUtilization(std::string name, double utilization);
  void DeleteNamedUtilization(const std::string& name);
  void SetAllNamedUtilization(std::map<std::string, double> named_utilization);

 private:
  class Reactor;

  Slice GetOrCreateSerializedResponse();

  const absl::Duration min_report_duration_;

  grpc::internal::Mutex mu_;
  double cpu_utilization_ ABSL_GUARDED_BY(&mu_) = -1;
  double memory_utilization_ ABSL_GUARDED_BY(&mu_) = -1;
  std::map<std::string, double> named_utilization_ ABSL_GUARDED_BY(&mu_);
  absl::optional<Slice> response_slice_ ABSL_GUARDED_BY(&mu_);
};

}  // namespace experimental
}  // namespace grpc

#endif  // GRPCPP_EXT_ORCA_SERVICE_H