// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SERVICES_DEVICE_GENERIC_SENSOR_VIRTUAL_PLATFORM_SENSOR_H_
#define SERVICES_DEVICE_GENERIC_SENSOR_VIRTUAL_PLATFORM_SENSOR_H_

#include <optional>

#include "base/memory/weak_ptr.h"
#include "services/device/generic_sensor/platform_sensor.h"
#include "services/device/public/cpp/generic_sensor/platform_sensor_configuration.h"
#include "services/device/public/cpp/generic_sensor/sensor_reading.h"
#include "services/device/public/mojom/sensor.mojom-shared.h"
#include "services/device/public/mojom/sensor_provider.mojom.h"

namespace device {

// OS-agnostic PlatformSensor implementation used in (web) tests. New instances
// are created by VirtualPlatformSensorProvider via GetSensor() calls.
//
// A VirtualPlatformSensor respects two invariants when it comes to readings
// added in the constructor or with AddReading():
// 1. Once a reading is set, it will remain set until it is replaced with
//    another reading.
// 2. Said reading will be added to the shared buffer (which may choose to
//    ignore it) and, on success, clients will be notified whenever the sensor
//    is activated (i.e. StartSensor() is called).
class VirtualPlatformSensor : public PlatformSensor {
 public:
  VirtualPlatformSensor(mojom::SensorType type,
                        SensorReadingSharedBuffer* reading_buffer,
                        base::WeakPtr<PlatformSensorProvider> provider,
                        std::optional<SensorReading> pending_reading,
                        const mojom::VirtualSensorMetadata& metadata);

  // Simulates the reporting of a new reading by a platform sensor.
  //
  // The process of adding a new reading is asynchronous (i.e. it always goes
  // via PostTask()). If the sensor is not active, the reading will be stashed
  // and added once the sensor is started again (with the original timestamp).
  //
  // The new reading still goes through the
  // UpdateSharedBufferAndNotifyClients() machinery, which means it may end up
  // not being stored (for example, if a threshold check fails).
  void AddReading(const SensorReading&);

  // Simulates that a platform sensor has been removed and therefore stopped
  // providing readings.
  void SimulateSensorRemoval();

  // Returns the current PlatformSensorConfiguration being used by the sensor
  // if it is currently active, or a null std::optional otherwise.
  const std::optional<PlatformSensorConfiguration>& optimal_configuration()
      const {
    return optimal_configuration_;
  }

 protected:
  ~VirtualPlatformSensor() override;

 private:
  // PlatformSensor overrides.
  bool StartSensor(const PlatformSensorConfiguration& configuration) override;
  void StopSensor() override;
  mojom::ReportingMode GetReportingMode() override;
  PlatformSensorConfiguration GetDefaultConfiguration() override;
  bool CheckSensorConfiguration(
      const PlatformSensorConfiguration& configuration) override;
  double GetMinimumSupportedFrequency() override;
  double GetMaximumSupportedFrequency() override;

  void DoAddReadingSync(const SensorReading&);

  std::optional<double> minimum_supported_frequency_;
  std::optional<double> maximum_supported_frequency_;
  std::optional<PlatformSensorConfiguration> optimal_configuration_;
  std::optional<mojom::ReportingMode> reporting_mode_;

  // The latest reading passed to this sensor by either the constructor or
  // AddReading().
  //
  // It may or may not be stored into the shared buffer by
  // PlatformSensor depending on e.g. whether the sensor is active,
  // rounding/threshold checks etc. Nonetheless, it remains saved and will be
  // added again once StartSensor() is called.
  std::optional<SensorReading> current_reading_;

  base::WeakPtrFactory<VirtualPlatformSensor> weak_ptr_factory_{this};
};

}  // namespace device

#endif  // SERVICES_DEVICE_GENERIC_SENSOR_VIRTUAL_PLATFORM_SENSOR_H_