/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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.
 */

/**
 * This class is a simple simulation of a typical CMOS cellphone imager chip,
 * which outputs 12-bit Bayer-mosaic raw images.
 *
 * Unlike most real image sensors, this one's native color space is linear sRGB.
 *
 * The sensor is abstracted as operating as a pipeline 3 stages deep;
 * conceptually, each frame to be captured goes through these three stages. The
 * processing step for the sensor is marked off by vertical sync signals, which
 * indicate the start of readout of the oldest frame. The interval between
 * processing steps depends on the frame duration of the frame currently being
 * captured. The stages are 1) configure, 2) capture, and 3) readout. During
 * configuration, the sensor's registers for settings such as exposure time,
 * frame duration, and gain are set for the next frame to be captured. In stage
 * 2, the image data for the frame is actually captured by the sensor. Finally,
 * in stage 3, the just-captured data is read out and sent to the rest of the
 * system.
 *
 * The sensor is assumed to be rolling-shutter, so low-numbered rows of the
 * sensor are exposed earlier in time than larger-numbered rows, with the time
 * offset between each row being equal to the row readout time.
 *
 * The characteristics of this sensor don't correspond to any actual sensor,
 * but are not far off typical sensors.
 *
 * Example timing diagram, with three frames:
 *  Frame 0-1: Frame duration 50 ms, exposure time 20 ms.
 *  Frame   2: Frame duration 75 ms, exposure time 65 ms.
 * Legend:
 *   C = update sensor registers for frame
 *   v = row in reset (vertical blanking interval)
 *   E = row capturing image data
 *   R = row being read out
 *   | = vertical sync signal
 *time(ms)|   0          55        105       155            230     270
 * Frame 0|   :configure : capture : readout :              :       :
 *  Row # | ..|CCCC______|_________|_________|              :       :
 *      0 |   :\          \vvvvvEEEER         \             :       :
 *    500 |   : \          \vvvvvEEEER         \            :       :
 *   1000 |   :  \          \vvvvvEEEER         \           :       :
 *   1500 |   :   \          \vvvvvEEEER         \          :       :
 *   2000 |   :    \__________\vvvvvEEEER_________\         :       :
 * Frame 1|   :           configure  capture      readout   :       :
 *  Row # |   :          |CCCC_____|_________|______________|       :
 *      0 |   :          :\         \vvvvvEEEER              \      :
 *    500 |   :          : \         \vvvvvEEEER              \     :
 *   1000 |   :          :  \         \vvvvvEEEER              \    :
 *   1500 |   :          :   \         \vvvvvEEEER              \   :
 *   2000 |   :          :    \_________\vvvvvEEEER______________\  :
 * Frame 2|   :          :          configure     capture    readout:
 *  Row # |   :          :         |CCCC_____|______________|_______|...
 *      0 |   :          :         :\         \vEEEEEEEEEEEEER       \
 *    500 |   :          :         : \         \vEEEEEEEEEEEEER       \
 *   1000 |   :          :         :  \         \vEEEEEEEEEEEEER       \
 *   1500 |   :          :         :   \         \vEEEEEEEEEEEEER       \
 *   2000 |   :          :         :    \_________\vEEEEEEEEEEEEER_______\
 */

#ifndef HW_EMULATOR_CAMERA2_SENSOR_H
#define HW_EMULATOR_CAMERA2_SENSOR_H

#include "utils/Mutex.h"
#include "utils/Thread.h"
#include "utils/Timers.h"

#include "Base.h"
#include "Scene.h"

namespace android {

class EmulatedFakeCamera2;

class Sensor : private Thread, public virtual RefBase {
 public:
  // width: Width of pixel array
  // height: Height of pixel array
  Sensor(uint32_t width, uint32_t height);
  ~Sensor();

  /*
   * Power control
   */

  status_t startUp();
  status_t shutDown();

  /*
   * Access to scene
   */
  Scene &getScene();

  /*
   * Controls that can be updated every frame
   */

  void setExposureTime(uint64_t ns);
  void setFrameDuration(uint64_t ns);
  void setSensitivity(uint32_t gain);
  // Buffer must be at least stride*height*2 bytes in size
  void setDestinationBuffers(Buffers *buffers);
  // To simplify tracking sensor's current frame
  void setFrameNumber(uint32_t frameNumber);

  /*
   * Controls that cause reconfiguration delay
   */

  void setBinning(int horizontalFactor, int verticalFactor);

  /*
   * Synchronizing with sensor operation (vertical sync)
   */

  // Wait until the sensor outputs its next vertical sync signal, meaning it
  // is starting readout of its latest frame of data. Returns true if vertical
  // sync is signaled, false if the wait timed out.
  bool waitForVSync(nsecs_t reltime);

  // Wait until a new frame has been read out, and then return the time
  // capture started.  May return immediately if a new frame has been pushed
  // since the last wait for a new frame. Returns true if new frame is
  // returned, false if timed out.
  bool waitForNewFrame(nsecs_t reltime, nsecs_t *captureTime);

  /*
   * Interrupt event servicing from the sensor. Only triggers for sensor
   * cycles that have valid buffers to write to.
   */
  struct SensorListener {
    enum Event {
      EXPOSURE_START,  // Start of exposure
    };

    virtual void onSensorEvent(uint32_t frameNumber, Event e,
                               nsecs_t timestamp) = 0;
    virtual ~SensorListener();
  };

  void setSensorListener(SensorListener *listener);

  /**
   * Static sensor characteristics
   */
  const uint32_t mResolution[2];
  const uint32_t mActiveArray[4];

  static const nsecs_t kExposureTimeRange[2];
  static const nsecs_t kFrameDurationRange[2];
  static const nsecs_t kMinVerticalBlank;

  static const uint8_t kColorFilterArrangement;

  // Output image data characteristics
  static const uint32_t kMaxRawValue;
  static const uint32_t kBlackLevel;
  // Sensor sensitivity, approximate

  static const float kSaturationVoltage;
  static const uint32_t kSaturationElectrons;
  static const float kVoltsPerLuxSecond;
  static const float kElectronsPerLuxSecond;

  static const float kBaseGainFactor;

  static const float kReadNoiseStddevBeforeGain;  // In electrons
  static const float kReadNoiseStddevAfterGain;   // In raw digital units
  static const float kReadNoiseVarBeforeGain;
  static const float kReadNoiseVarAfterGain;

  // While each row has to read out, reset, and then expose, the (reset +
  // expose) sequence can be overlapped by other row readouts, so the final
  // minimum frame duration is purely a function of row readout time, at least
  // if there's a reasonable number of rows.
  const nsecs_t mRowReadoutTime;

  static const int32_t kSensitivityRange[2];
  static const uint32_t kDefaultSensitivity;

 private:
  Mutex mControlMutex;  // Lock before accessing control parameters
  // Start of control parameters
  Condition mVSync;
  bool mGotVSync;
  uint64_t mExposureTime;
  uint64_t mFrameDuration;
  uint32_t mGainFactor;
  Buffers *mNextBuffers;
  uint32_t mFrameNumber;

  // End of control parameters

  Mutex mReadoutMutex;  // Lock before accessing readout variables
  // Start of readout variables
  Condition mReadoutAvailable;
  Condition mReadoutComplete;
  Buffers *mCapturedBuffers;
  nsecs_t mCaptureTime;
  SensorListener *mListener;
  // End of readout variables

  // Time of sensor startup, used for simulation zero-time point
  nsecs_t mStartupTime;

  /**
   * Inherited Thread virtual overrides, and members only used by the
   * processing thread
   */
 private:
  virtual status_t readyToRun();

  virtual bool threadLoop();

  nsecs_t mNextCaptureTime;
  Buffers *mNextCapturedBuffers;

  Scene mScene;

  void captureRaw(uint8_t *img, uint32_t gain, uint32_t stride);
  void captureRGBA(uint8_t *img, uint32_t gain, uint32_t stride);
  void captureRGB(uint8_t *img, uint32_t gain, uint32_t stride);
  void captureNV21(uint8_t *img, uint32_t gain, uint32_t stride);
  void captureDepth(uint8_t *img, uint32_t gain, uint32_t stride);
  void captureDepthCloud(uint8_t *img);
};

}  // namespace android

#endif  // HW_EMULATOR_CAMERA2_SENSOR_H