/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2017. All Rights Reserved.                        */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

package edu.wpi.first.wpilibj;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;

import edu.wpi.first.wpilibj.hal.AnalogJNI;
import edu.wpi.first.wpilibj.hal.FRCNetComm.tResourceType;
import edu.wpi.first.wpilibj.hal.HAL;
import edu.wpi.first.wpilibj.livewindow.LiveWindow;
import edu.wpi.first.wpilibj.livewindow.LiveWindowSendable;
import edu.wpi.first.wpilibj.tables.ITable;
import edu.wpi.first.wpilibj.util.AllocationException;

/**
 * Analog channel class.
 *
 * <p>Each analog channel is read from hardware as a 12-bit number representing 0V to 5V.
 *
 * <p>Connected to each analog channel is an averaging and oversampling engine. This engine
 * accumulates the specified ( by setAverageBits() and setOversampleBits() ) number of samples
 * before returning a new value. This is not a sliding window average. The only difference between
 * the oversampled samples and the averaged samples is that the oversampled samples are simply
 * accumulated effectively increasing the resolution, while the averaged samples are divided by the
 * number of samples to retain the resolution, but get more stable values.
 */
public class AnalogInput extends SensorBase implements PIDSource, LiveWindowSendable {

  private static final int kAccumulatorSlot = 1;
  int m_port; // explicit no modifier, private and package accessable.
  private int m_channel;
  private static final int[] kAccumulatorChannels = {0, 1};
  private long m_accumulatorOffset;
  protected PIDSourceType m_pidSource = PIDSourceType.kDisplacement;

  /**
   * Construct an analog channel.
   *
   * @param channel The channel number to represent. 0-3 are on-board 4-7 are on the MXP port.
   */
  public AnalogInput(final int channel) {
    m_channel = channel;

    SensorBase.checkAnalogInputChannel(channel);

    final int portHandle = AnalogJNI.getPort((byte) channel);
    m_port = AnalogJNI.initializeAnalogInputPort(portHandle);

    LiveWindow.addSensor("AnalogInput", channel, this);
    HAL.report(tResourceType.kResourceType_AnalogChannel, channel);
  }

  /**
   * Channel destructor.
   */
  public void free() {
    AnalogJNI.freeAnalogInputPort(m_port);
    m_port = 0;
    m_channel = 0;
    m_accumulatorOffset = 0;
  }

  /**
   * Get a sample straight from this channel. The sample is a 12-bit value representing the 0V to 5V
   * range of the A/D converter. The units are in A/D converter codes. Use GetVoltage() to get the
   * analog value in calibrated units.
   *
   * @return A sample straight from this channel.
   */
  public int getValue() {
    return AnalogJNI.getAnalogValue(m_port);
  }

  /**
   * Get a sample from the output of the oversample and average engine for this channel. The sample
   * is 12-bit + the bits configured in SetOversampleBits(). The value configured in
   * setAverageBits() will cause this value to be averaged 2^bits number of samples. This is not a
   * sliding window. The sample will not change until 2^(OversampleBits + AverageBits) samples have
   * been acquired from this channel. Use getAverageVoltage() to get the analog value in calibrated
   * units.
   *
   * @return A sample from the oversample and average engine for this channel.
   */
  public int getAverageValue() {
    return AnalogJNI.getAnalogAverageValue(m_port);
  }

  /**
   * Get a scaled sample straight from this channel. The value is scaled to units of Volts using the
   * calibrated scaling data from getLSBWeight() and getOffset().
   *
   * @return A scaled sample straight from this channel.
   */
  public double getVoltage() {
    return AnalogJNI.getAnalogVoltage(m_port);
  }

  /**
   * Get a scaled sample from the output of the oversample and average engine for this channel. The
   * value is scaled to units of Volts using the calibrated scaling data from getLSBWeight() and
   * getOffset(). Using oversampling will cause this value to be higher resolution, but it will
   * update more slowly. Using averaging will cause this value to be more stable, but it will update
   * more slowly.
   *
   * @return A scaled sample from the output of the oversample and average engine for this channel.
   */
  public double getAverageVoltage() {
    return AnalogJNI.getAnalogAverageVoltage(m_port);
  }

  /**
   * Get the factory scaling least significant bit weight constant. The least significant bit weight
   * constant for the channel that was calibrated in manufacturing and stored in an eeprom.
   *
   * <p>Volts = ((LSB_Weight * 1e-9) * raw) - (Offset * 1e-9)
   *
   * @return Least significant bit weight.
   */
  public long getLSBWeight() {
    return AnalogJNI.getAnalogLSBWeight(m_port);
  }

  /**
   * Get the factory scaling offset constant. The offset constant for the channel that was
   * calibrated in manufacturing and stored in an eeprom.
   *
   * <p>Volts = ((LSB_Weight * 1e-9) * raw) - (Offset * 1e-9)
   *
   * @return Offset constant.
   */
  public int getOffset() {
    return AnalogJNI.getAnalogOffset(m_port);
  }

  /**
   * Get the channel number.
   *
   * @return The channel number.
   */
  public int getChannel() {
    return m_channel;
  }

  /**
   * Set the number of averaging bits. This sets the number of averaging bits. The actual number of
   * averaged samples is 2^bits. The averaging is done automatically in the FPGA.
   *
   * @param bits The number of averaging bits.
   */
  public void setAverageBits(final int bits) {
    AnalogJNI.setAnalogAverageBits(m_port, bits);
  }

  /**
   * Get the number of averaging bits. This gets the number of averaging bits from the FPGA. The
   * actual number of averaged samples is 2^bits. The averaging is done automatically in the FPGA.
   *
   * @return The number of averaging bits.
   */
  public int getAverageBits() {
    return AnalogJNI.getAnalogAverageBits(m_port);
  }

  /**
   * Set the number of oversample bits. This sets the number of oversample bits. The actual number
   * of oversampled values is 2^bits. The oversampling is done automatically in the FPGA.
   *
   * @param bits The number of oversample bits.
   */
  public void setOversampleBits(final int bits) {
    AnalogJNI.setAnalogOversampleBits(m_port, bits);
  }

  /**
   * Get the number of oversample bits. This gets the number of oversample bits from the FPGA. The
   * actual number of oversampled values is 2^bits. The oversampling is done automatically in the
   * FPGA.
   *
   * @return The number of oversample bits.
   */
  public int getOversampleBits() {
    return AnalogJNI.getAnalogOversampleBits(m_port);
  }

  /**
   * Initialize the accumulator.
   */
  public void initAccumulator() {
    if (!isAccumulatorChannel()) {
      throw new AllocationException("Accumulators are only available on slot " + kAccumulatorSlot
          + " on channels " + kAccumulatorChannels[0] + ", " + kAccumulatorChannels[1]);
    }
    m_accumulatorOffset = 0;
    AnalogJNI.initAccumulator(m_port);
  }

  /**
   * Set an initial value for the accumulator.
   *
   * <p>This will be added to all values returned to the user.
   *
   * @param initialValue The value that the accumulator should start from when reset.
   */
  public void setAccumulatorInitialValue(long initialValue) {
    m_accumulatorOffset = initialValue;
  }

  /**
   * Resets the accumulator to the initial value.
   */
  public void resetAccumulator() {
    AnalogJNI.resetAccumulator(m_port);

    // Wait until the next sample, so the next call to getAccumulator*()
    // won't have old values.
    final double sampleTime = 1.0 / getGlobalSampleRate();
    final double overSamples = 1 << getOversampleBits();
    final double averageSamples = 1 << getAverageBits();
    Timer.delay(sampleTime * overSamples * averageSamples);

  }

  /**
   * Set the center value of the accumulator.
   *
   * <p>The center value is subtracted from each A/D value before it is added to the accumulator.
   * This is used for the center value of devices like gyros and accelerometers to take the device
   * offset into account when integrating.
   *
   * <p>This center value is based on the output of the oversampled and averaged source the
   * accumulator channel. Because of this, any non-zero oversample bits will affect the size of the
   * value for this field.
   */
  public void setAccumulatorCenter(int center) {
    AnalogJNI.setAccumulatorCenter(m_port, center);
  }

  /**
   * Set the accumulator's deadband.
   *
   * @param deadband The deadband size in ADC codes (12-bit value)
   */
  public void setAccumulatorDeadband(int deadband) {
    AnalogJNI.setAccumulatorDeadband(m_port, deadband);
  }

  /**
   * Read the accumulated value.
   *
   * <p>Read the value that has been accumulating. The accumulator is attached after the oversample
   * and average engine.
   *
   * @return The 64-bit value accumulated since the last Reset().
   */
  public long getAccumulatorValue() {
    return AnalogJNI.getAccumulatorValue(m_port) + m_accumulatorOffset;
  }

  /**
   * Read the number of accumulated values.
   *
   * <p>Read the count of the accumulated values since the accumulator was last Reset().
   *
   * @return The number of times samples from the channel were accumulated.
   */
  public long getAccumulatorCount() {
    return AnalogJNI.getAccumulatorCount(m_port);
  }

  /**
   * Read the accumulated value and the number of accumulated values atomically.
   *
   * <p>This function reads the value and count from the FPGA atomically. This can be used for
   * averaging.
   *
   * @param result AccumulatorResult object to store the results in.
   */
  public void getAccumulatorOutput(AccumulatorResult result) {
    if (result == null) {
      throw new IllegalArgumentException("Null parameter `result'");
    }
    if (!isAccumulatorChannel()) {
      throw new IllegalArgumentException(
          "Channel " + m_channel + " is not an accumulator channel.");
    }
    ByteBuffer value = ByteBuffer.allocateDirect(8);
    // set the byte order
    value.order(ByteOrder.LITTLE_ENDIAN);
    ByteBuffer count = ByteBuffer.allocateDirect(8);
    // set the byte order
    count.order(ByteOrder.LITTLE_ENDIAN);
    AnalogJNI.getAccumulatorOutput(m_port, value.asLongBuffer(), count.asLongBuffer());
    result.value = value.asLongBuffer().get(0) + m_accumulatorOffset;
    result.count = count.asLongBuffer().get(0);
  }

  /**
   * Is the channel attached to an accumulator.
   *
   * @return The analog channel is attached to an accumulator.
   */
  public boolean isAccumulatorChannel() {
    for (int i = 0; i < kAccumulatorChannels.length; i++) {
      if (m_channel == kAccumulatorChannels[i]) {
        return true;
      }
    }
    return false;
  }

  /**
   * Set the sample rate per channel.
   *
   * <p>This is a global setting for all channels. The maximum rate is 500kS/s divided by the number
   * of channels in use. This is 62500 samples/s per channel if all 8 channels are used.
   *
   * @param samplesPerSecond The number of samples per second.
   */
  public static void setGlobalSampleRate(final double samplesPerSecond) {
    AnalogJNI.setAnalogSampleRate(samplesPerSecond);
  }

  /**
   * Get the current sample rate.
   *
   * <p>This assumes one entry in the scan list. This is a global setting for all channels.
   *
   * @return Sample rate.
   */
  public static double getGlobalSampleRate() {
    return AnalogJNI.getAnalogSampleRate();
  }

  @Override
  public void setPIDSourceType(PIDSourceType pidSource) {
    m_pidSource = pidSource;
  }

  @Override
  public PIDSourceType getPIDSourceType() {
    return m_pidSource;
  }

  /**
   * Get the average voltage for use with PIDController.
   *
   * @return the average voltage
   */
  @Override
  public double pidGet() {
    return getAverageVoltage();
  }

  /**
   * Live Window code, only does anything if live window is activated.
   */
  @Override
  public String getSmartDashboardType() {
    return "Analog Input";
  }

  private ITable m_table;

  @Override
  public void initTable(ITable subtable) {
    m_table = subtable;
    updateTable();
  }

  @Override
  public void updateTable() {
    if (m_table != null) {
      m_table.putNumber("Value", getAverageVoltage());
    }
  }

  @Override
  public ITable getTable() {
    return m_table;
  }

  /**
   * Analog Channels don't have to do anything special when entering the LiveWindow. {@inheritDoc}
   */
  @Override
  public void startLiveWindowMode() {
  }

  /**
   * Analog Channels don't have to do anything special when exiting the LiveWindow. {@inheritDoc}
   */
  @Override
  public void stopLiveWindowMode() {
  }
}