#ifndef THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HAL_SHARED_MEM_SERVER_H_
#define THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HAL_SHARED_MEM_SERVER_H_

#include <cstdint>
#include <memory>
#include <string>
#include <string_view>
#include <utility>

#include "absl/base/thread_annotations.h"
#include "absl/container/flat_hash_map.h"
#include "absl/flags/declare.h"
#include "absl/status/statusor.h"
#include "absl/synchronization/mutex.h"
#include "absl/time/time.h"
#include "tlbmc/hal/shared_mem/metrics.h"
#include "tlbmc/hal/shared_mem/segment_manager.h"
#include "tlbmc/hal/shared_mem/sensors.h"

namespace milotic_tlbmc {

class IpcServer {
 public:
  virtual ~IpcServer() = default;
  // Returns the sensor value and timestamp given the sensor name.
  virtual absl::StatusOr<std::pair<float, uint64_t>> ReadSensorValue(
      const std::string& sensor_name) = 0;
  // copybara:strip_begin(g3-shared-libs)
  virtual void UpdateMetricsRequestCount(bool is_tlbmc_request) = 0;
  virtual void UpdateMetricsResponse(absl::Duration response_time,
                                     int status_code,
                                     std::string_view resource_url) = 0;
  // copybara:strip_end
  virtual const TlbmcMetrics* GetMetrics() const = 0;
};

// The class is thread-safe.
// Typical usage (sensor):
//   SharedMemoryServer::Initialize();
//   IpcServer& server = SharedMemoryServer::GetInstance();
//   while (true) {
//     server.ReadSensorValue("sensor001");
//     time.sleep(1ms);
//   }
// Typical usage (metrics):
//   SharedMemoryServer::Initialize();
//   IpcServer& server = SharedMemoryServer::GetInstance();
//   while (true) {
//     server.UpdateMetricsXxx();
//     time.sleep(1ms);
//   }
class SharedMemoryServer : public IpcServer {
 private:
  class Token;

 public:
  static void Initialize();
  static IpcServer& GetInstance();
  // Avoid permission issues in /run/.
  static void SetUpInstanceForUnitTest();
  virtual ~SharedMemoryServer() = default;

  // Sensor APIs.
  absl::StatusOr<std::pair<float, uint64_t>> ReadSensorValue(
      const std::string& sensor_name) override;

  // Metrics APIs.
  const TlbmcMetrics* GetMetrics() const override { return metrics_; }
  // copybara:strip_begin(g3-shared-libs)
  void UpdateMetricsRequestCount(bool is_tlbmc_request) override;
  void UpdateMetricsResponse(absl::Duration response_time, int status_code,
                             std::string_view resource_url) override;
  // copybara:strip_end

  SharedMemoryServer(Token token, const std::string& initialized_file_path,
                     std::unique_ptr<SegmentManager> segment_manager);

  static void Initialize(const std::string& initialized_file_path);

 protected:
  SharedMemoryServer(const std::string& initialized_file_path,
                     std::unique_ptr<SegmentManager> segment_manager);

  SharedMemoryServer() = default;
  IpcSensor* GetSensor(const std::string& sensor_name)
      ABSL_LOCKS_EXCLUDED(sensors_mutex_);

  // For testing only. Provides the ability to set `initialized_file_path` which
  // works in test environment.
  static IpcServer& GetInstance(const std::string& initialized_file_path);

 private:
  class Token {
   private:
    explicit Token() = default;
    friend SharedMemoryServer;
  };
  const std::string initialized_file_path_;
  const std::unique_ptr<SegmentManager> segment_manager_;
  absl::Mutex sensors_mutex_;
  absl::flat_hash_map<std::string, IpcSensor*> sensors_
      ABSL_GUARDED_BY(sensors_mutex_);
  TlbmcMetrics* const metrics_ = nullptr;
};

}  // namespace milotic_tlbmc

#endif  // THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_HAL_SHARED_MEM_SERVER_H_