/*----------------------------------------------------------------------------*/
/* 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 edu.wpi.first.wpilibj.hal.AnalogJNI;
import edu.wpi.first.wpilibj.hal.FRCNetComm.tResourceType;
import edu.wpi.first.wpilibj.hal.HAL;

/**
 * Class to represent a specific output from an analog trigger. This class is used to get the
 * current output value and also as a DigitalSource to provide routing of an output to digital
 * subsystems on the FPGA such as Counter, Encoder, and Interrupt.
 *
 * <p>The TriggerState output indicates the primary output value of the trigger. If the analog
 * signal is less than the lower limit, the output is false. If the analog value is greater than the
 * upper limit, then the output is true. If the analog value is in between, then the trigger output
 * state maintains its most recent value.
 *
 * <p>The InWindow output indicates whether or not the analog signal is inside the range defined by
 * the limits.
 *
 * <p>The RisingPulse and FallingPulse outputs detect an instantaneous transition from above the
 * upper limit to below the lower limit, and vise versa. These pulses represent a rollover condition
 * of a sensor and can be routed to an up / down counter or to interrupts. Because the outputs
 * generate a pulse, they cannot be read directly. To help ensure that a rollover condition is not
 * missed, there is an average rejection filter available that operates on the upper 8 bits of a 12
 * bit number and selects the nearest outlyer of 3 samples. This will reject a sample that is (due
 * to averaging or sampling) errantly between the two limits. This filter will fail if more than one
 * sample in a row is errantly in between the two limits. You may see this problem if attempting to
 * use this feature with a mechanical rollover sensor, such as a 360 degree no-stop potentiometer
 * without signal conditioning, because the rollover transition is not sharp / clean enough. Using
 * the averaging engine may help with this, but rotational speeds of the sensor will then be
 * limited.
 */
public class AnalogTriggerOutput extends DigitalSource {

  /**
   * Exceptions dealing with improper operation of the Analog trigger output.
   */
  public class AnalogTriggerOutputException extends RuntimeException {
    /**
     * Create a new exception with the given message.
     *
     * @param message the message to pass with the exception
     */
    public AnalogTriggerOutputException(String message) {
      super(message);
    }
  }

  private final AnalogTrigger m_trigger;
  private final AnalogTriggerType m_outputType;

  /**
   * Create an object that represents one of the four outputs from an analog trigger.
   *
   * <p>Because this class derives from DigitalSource, it can be passed into routing functions for
   * Counter, Encoder, etc.
   *
   * @param trigger    The trigger for which this is an output.
   * @param outputType An enum that specifies the output on the trigger to represent.
   */
  public AnalogTriggerOutput(AnalogTrigger trigger, final AnalogTriggerType outputType) {
    if (trigger == null) {
      throw new NullPointerException("Analog Trigger given was null");
    }
    if (outputType == null) {
      throw new NullPointerException("Analog Trigger Type given was null");
    }
    m_trigger = trigger;
    m_outputType = outputType;

    HAL.report(tResourceType.kResourceType_AnalogTriggerOutput,
        trigger.getIndex(), outputType.value);
  }

  /**
   * Frees the resources for this output.
   */
  public void free() {
    if (m_interrupt != 0) {
      cancelInterrupts();
    }

  }

  /**
   * Get the state of the analog trigger output.
   *
   * @return The state of the analog trigger output.
   */
  public boolean get() {
    return AnalogJNI.getAnalogTriggerOutput(m_trigger.m_port, m_outputType.value);
  }

  @Override
  public int getPortHandleForRouting() {
    return m_trigger.m_port;
  }

  @Override
  public int getAnalogTriggerTypeForRouting() {
    return m_outputType.value;
  }

  @Override
  public int getChannel() {
    return m_trigger.m_index;
  }

  @Override
  public boolean isAnalogTrigger() {
    return true;
  }

  /**
   * Defines the state in which the AnalogTrigger triggers.
   */
  public enum AnalogTriggerType {
    kInWindow(AnalogJNI.AnalogTriggerType.kInWindow), kState(AnalogJNI.AnalogTriggerType.kState),
    kRisingPulse(AnalogJNI.AnalogTriggerType.kRisingPulse),
    kFallingPulse(AnalogJNI.AnalogTriggerType.kFallingPulse);

    @SuppressWarnings("MemberName")
    private final int value;

    private AnalogTriggerType(int value) {
      this.value = value;
    }
  }
}