#ifndef THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_SENSORS_SENSOR_H_
#define THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_SENSORS_SENSOR_H_

#include <chrono>  // NOLINT
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <utility>
#include <vector>

#include "absl/base/thread_annotations.h"
#include "absl/container/btree_set.h"
#include "absl/functional/any_invocable.h"
#include "absl/functional/function_ref.h"
#include "absl/log/log.h"
#include "absl/status/status.h"
#include "absl/strings/string_view.h"
#include "absl/synchronization/mutex.h"
#include "absl/time/time.h"
#include "boost/circular_buffer.hpp"  //NOLINT: boost is commonly used in BMC
#include "entity_common_config.pb.h"
#include "hal_common_config.pb.h"
#include "reading_transform_config.pb.h"
#include "tlbmc/configs/subscription_config.h"
#include "tlbmc/hal/sysfs/i2c.h"
#include "resource.pb.h"
#include "sensor.pb.h"

namespace milotic_tlbmc {

std::string GetTrimmedSensorName(absl::string_view sensor_name);

// Any implementation of this interface must be thread-safe regarding the listed
// functions.
class Sensor {
 public:
  // Callback used export batch of sensor data.
  using NotificationCb = absl::FunctionRef<void(
      std::vector<std::shared_ptr<const SensorValue>>&&)>;

  static SensorAttributesStatic CreateStaticAttributes(
      absl::string_view sensor_name, const SensorUnit& sensor_unit,
      const HalCommonConfig& hal_common_config,
      const EntityCommonConfig& entity_common_config,
      const ReadingRangeConfigs& reading_range_configs,
      const ReadingTransformConfig& reading_transform_config);

  virtual ~Sensor() = default;

  // Returns the latest sensor reading.
  std::shared_ptr<const SensorValue> GetSensorData() const
      ABSL_LOCKS_EXCLUDED(sensor_data_mutex_) {
    absl::MutexLock lock(&sensor_data_mutex_);
    return sensor_data_.empty() ? nullptr : sensor_data_.back();
  }

  std::vector<std::shared_ptr<const SensorValue>> GetSensorDataHistory() const
      ABSL_LOCKS_EXCLUDED(sensor_data_mutex_) {
    absl::MutexLock lock(&sensor_data_mutex_);
    return {sensor_data_.begin(), sensor_data_.end()};
  }

  std::vector<std::shared_ptr<const SensorValue>> GetSensorDataHistorySince(
      absl::Time start_time) const ABSL_LOCKS_EXCLUDED(sensor_data_mutex_);

  // Refreshes the sensor data once asynchronously. The sensor data will be
  // updated when the refresh is done. On errors, nullptr will be fed to the
  // callback. Detailed error message can be found in the sensor's state.
  // The `callback` will be called when the refresh is done with the SensorData
  // that has been refreshed or nullptr if there is an error. The `callback` can
  // be nullptr. The callback is supposed to be blocking.
  // Implementation is also supposed to implement metrics update in this method.
  virtual void RefreshOnceAsync(
      absl::AnyInvocable<void(const std::shared_ptr<const SensorValue>&)>
          callback) = 0;

  // Writes the sensor reading to the sensor hardware synchronously.
  // Note, this does not update the cached sensor data directly. Sensor data is
  // still updated asynchronously by `RefreshOnceAsync`.
  virtual absl::Status WriteReading(const SensorValue& value);

  // Returns the key of the sensor. A key shall be constant for a sensor's
  // lifetime.
  std::string GetKey() const {
    return sensor_attributes_static_.attributes().key();
  }

  // Returns the config key of the board that contains this sensor.
  std::string GetBoardConfigKey() const {
    return sensor_attributes_static_.entity_common_config().board_config_key();
  }

  SensorAttributesDynamic GetSensorAttributesDynamic() const {
    absl::MutexLock lock(&sensor_attributes_dynamic_mutex_);
    return sensor_attributes_dynamic_;
  }

  const SensorAttributesStatic& GetSensorAttributesStatic() const {
    return sensor_attributes_static_;
  }

  SensorMetrics GetSensorMetrics() const;

  // Subscribes to the sensor data.
  absl::Status Subscribe(const SubscriptionParams* subscription_params);
  // Deletes an existing subscription.
  absl::Status Unsubscribe(const SubscriptionParams* subscription_params);
  void UpdateState(State&& state);
  // Updates the thresholds for the sensor.
  void UpdateThresholds(const ThresholdConfigs& threshold_configs);
  // Resize the buffer for the sensor.
  void ResizeBuffer(size_t buffer_size);
  // Resets the metrics for the sensor. This is used when the sensor is
  // configured with a different sampling interval.
  void ResetMetrics();
  // When a sensor is configured with a different sampling interval, we use this
  // function to update the sampling interval in the sensor dynamic attributes
  void UpdateSensorSamplingInterval(absl::Duration new_sampling_interval);

  // Since Reinitialize may have to be performed asynchronously, we will invoke
  // the callback when the reinitialization is done. The status passed to it
  // will indicate the status of the reinitialization.
  virtual void Reinitialize(absl::AnyInvocable<void(absl::Status)> callback) {
    callback(absl::UnimplementedError("Reinitialize is not implemented for " +
                                      GetKey() +
                                      " with "
                                      "config " +
                                      GetBoardConfigKey()));
  }

 protected:
  Sensor(SensorAttributesStatic&& sensor_attributes_static,
         const ThresholdConfigs& threshold_configs,
         std::optional<NotificationCb> notification_cb)
      : sensor_attributes_static_(std::move(sensor_attributes_static)),
        sensor_data_(static_cast<size_t>(
            sensor_attributes_static_.entity_common_config().queue_size())),
        notification_cb_(notification_cb) {
    UpdateThresholds(threshold_configs);
  }
  Sensor() : sensor_data_(1) {
    DLOG(INFO) << "Sensor created with default queue size of "
               << sensor_data_.capacity();
  }

  // Buffers the sensor data and notifies the subscribers if the batch size
  // reaches the threshold.
  void StoreSensorData(const std::shared_ptr<const SensorValue>& sensor_data)
      ABSL_LOCKS_EXCLUDED(sensor_data_mutex_, sensor_attributes_dynamic_mutex_);

  // Given the latency of the most recent hardware polling latency, updates the
  // metrics.
  void UpdateHardwarePollingMetrics(std::chrono::steady_clock::duration latency)
      ABSL_LOCKS_EXCLUDED(sensor_metrics_mutex_);

  // Given the timestamp of the most recent software polling read start
  // interval, updates the metrics.
  void UpdateSoftwarePollingStartMetrics(
      std::chrono::steady_clock::duration interval)
      ABSL_LOCKS_EXCLUDED(sensor_metrics_mutex_);

  // Given the timestamp of the most recent software polling read end interval,
  // updates the metrics.
  void UpdateSoftwarePollingEndMetrics(
      std::chrono::steady_clock::duration interval)
      ABSL_LOCKS_EXCLUDED(sensor_metrics_mutex_);

  void SetLastRefreshStartTime(std::chrono::steady_clock::time_point time) {
    // NOLINTNEXTLINE: Yocto's Abseil doesn't support non-pointer constructor.
    absl::MutexLock lock(&sensor_metrics_mutex_);
    last_refresh_start_time_ = time;
  }

  std::chrono::steady_clock::time_point GetLastRefreshStartTime() const {
    // NOLINTNEXTLINE: Yocto's Abseil doesn't support non-pointer constructor.
    absl::MutexLock lock(&sensor_metrics_mutex_);
    return last_refresh_start_time_;
  }

  void SetLastRefreshEndTime(std::chrono::steady_clock::time_point time) {
    // NOLINTNEXTLINE: Yocto's Abseil doesn't support non-pointer constructor.
    absl::MutexLock lock(&sensor_metrics_mutex_);
    last_refresh_end_time_ = time;
  }

  std::chrono::steady_clock::time_point GetLastRefreshEndTime() const {
    // NOLINTNEXTLINE: Yocto's Abseil doesn't support non-pointer constructor.
    absl::MutexLock lock(&sensor_metrics_mutex_);
    return last_refresh_end_time_;
  }

  const SensorAttributesStatic sensor_attributes_static_;

  mutable absl::Mutex sensor_attributes_dynamic_mutex_;
  SensorAttributesDynamic sensor_attributes_dynamic_
      ABSL_GUARDED_BY(sensor_attributes_dynamic_mutex_);

  mutable absl::Mutex sensor_data_mutex_;
  // Front() returns the oldest data.
  boost::circular_buffer<std::shared_ptr<const SensorValue>> sensor_data_
      ABSL_GUARDED_BY(sensor_data_mutex_);

  // The set of batch sizes that are subscribed to the sensor.
  absl::btree_set<const SubscriptionParams*, SubscriptionParams::Compare>
      subscription_params_ ABSL_GUARDED_BY(sensor_attributes_dynamic_mutex_);
  // Callback to be invoked when the batch size reaches the threshold.
  // Not locked: The callback is instantiated in the constructor and is
  // supposed to be invoked from a single io_context thread.
  const std::optional<NotificationCb> notification_cb_ = std::nullopt;

  mutable absl::Mutex sensor_metrics_mutex_;
  // The total number of hardware reads.
  uint64_t total_hardware_read_cnt_ = 0;
  // The total latency of hardware reads in milliseconds.
  uint64_t total_hardware_latency_ms_ = 0;
  // The total software polling start interval in milliseconds.
  uint64_t total_software_polling_start_interval_ms_ = 0;
  // The total number of software polling start.
  uint64_t total_software_polling_start_cnt_ = 0;
  // The total software polling end interval in milliseconds.
  uint64_t total_software_polling_end_interval_ms_ = 0;
  // The total number of software polling end.
  uint64_t total_software_polling_end_cnt_ = 0;
  std::chrono::steady_clock::time_point last_refresh_start_time_ =
      std::chrono::steady_clock::time_point::min();
  std::chrono::steady_clock::time_point last_refresh_end_time_ =
      std::chrono::steady_clock::time_point::min();
};

}  // namespace milotic_tlbmc

#endif  // THIRD_PARTY_MILOTIC_EXTERNAL_CC_TLBMC_SENSORS_SENSOR_H_