/*----------------------------------------------------------------------------*/
/* Copyright (c) 2008-2018 FIRST. 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.FRCNetComm.tResourceType;
import edu.wpi.first.wpilibj.hal.HAL;
import edu.wpi.first.wpilibj.hal.RelayJNI;
import edu.wpi.first.wpilibj.smartdashboard.SendableBuilder;

import java.util.Arrays;
import java.util.Optional;

import static java.util.Objects.requireNonNull;

/**
 * Class for VEX Robotics Spike style relay outputs. Relays are intended to be connected to Spikes
 * or similar relays. The relay channels controls a pair of channels that are either both off, one
 * on, the other on, or both on. This translates into two Spike outputs at 0v, one at 12v and one
 * at 0v, one at 0v and the other at 12v, or two Spike outputs at 12V. This allows off, full
 * forward, or full reverse control of motors without variable speed. It also allows the two
 * channels (forward and reverse) to be used independently for something that does not care about
 * voltage polarity (like a solenoid).
 */
public class Relay extends SendableBase implements MotorSafety, Sendable {
  private MotorSafetyHelper m_safetyHelper;

  /**
   * This class represents errors in trying to set relay values contradictory to the direction to
   * which the relay is set.
   */
  public class InvalidValueException extends RuntimeException {
    /**
     * Create a new exception with the given message.
     *
     * @param message the message to pass with the exception
     */
    public InvalidValueException(String message) {
      super(message);
    }
  }

  /**
   * The state to drive a Relay to.
   */
  public enum Value {
    kOff("Off"),
    kOn("On"),
    kForward("Forward"),
    kReverse("Reverse");

    private final String m_prettyValue;

    Value(String prettyValue) {
      m_prettyValue = prettyValue;
    }

    public String getPrettyValue() {
      return m_prettyValue;
    }

    public static Optional<Value> getValueOf(String value) {
      return Arrays.stream(Value.values()).filter(v -> v.m_prettyValue.equals(value)).findFirst();
    }
  }

  /**
   * The Direction(s) that a relay is configured to operate in.
   */
  public enum Direction {
    /**
     * direction: both directions are valid.
     */

    kBoth,
    /**
     * direction: Only forward is valid.
     */
    kForward,
    /**
     * direction: only reverse is valid.
     */
    kReverse
  }

  private final int m_channel;

  private int m_forwardHandle = 0;
  private int m_reverseHandle = 0;

  private Direction m_direction;

  /**
   * Common relay initialization method. This code is common to all Relay constructors and
   * initializes the relay and reserves all resources that need to be locked. Initially the relay is
   * set to both lines at 0v.
   */
  private void initRelay() {
    SensorBase.checkRelayChannel(m_channel);

    int portHandle = RelayJNI.getPort((byte) m_channel);
    if (m_direction == Direction.kBoth || m_direction == Direction.kForward) {
      m_forwardHandle = RelayJNI.initializeRelayPort(portHandle, true);
      HAL.report(tResourceType.kResourceType_Relay, m_channel);
    }
    if (m_direction == Direction.kBoth || m_direction == Direction.kReverse) {
      m_reverseHandle = RelayJNI.initializeRelayPort(portHandle, false);
      HAL.report(tResourceType.kResourceType_Relay, m_channel + 128);
    }

    m_safetyHelper = new MotorSafetyHelper(this);
    m_safetyHelper.setSafetyEnabled(false);

    setName("Relay", m_channel);
  }

  /**
   * Relay constructor given a channel.
   *
   * @param channel The channel number for this relay (0 - 3).
   * @param direction The direction that the Relay object will control.
   */
  public Relay(final int channel, Direction direction) {
    m_channel = channel;
    m_direction = requireNonNull(direction, "Null Direction was given");
    initRelay();
    set(Value.kOff);
  }

  /**
   * Relay constructor given a channel, allowing both directions.
   *
   * @param channel The channel number for this relay (0 - 3).
   */
  public Relay(final int channel) {
    this(channel, Direction.kBoth);
  }

  @Override
  public void free() {
    super.free();
    freeRelay();
  }

  private void freeRelay() {
    try {
      RelayJNI.setRelay(m_forwardHandle, false);
    } catch (RuntimeException ex) {
      // do nothing. Ignore
    }
    try {
      RelayJNI.setRelay(m_reverseHandle, false);
    } catch (RuntimeException ex) {
      // do nothing. Ignore
    }

    RelayJNI.freeRelayPort(m_forwardHandle);
    RelayJNI.freeRelayPort(m_reverseHandle);

    m_forwardHandle = 0;
    m_reverseHandle = 0;
  }

  /**
   * Set the relay state.
   *
   * <p>Valid values depend on which directions of the relay are controlled by the object.
   *
   * <p>When set to kBothDirections, the relay can be set to any of the four states: 0v-0v, 12v-0v,
   * 0v-12v, 12v-12v
   *
   * <p>When set to kForwardOnly or kReverseOnly, you can specify the constant for the direction or
   * you can simply specify kOff and kOn. Using only kOff and kOn is recommended.
   *
   * @param value The state to set the relay.
   */
  public void set(Value value) {
    switch (value) {
      case kOff:
        if (m_direction == Direction.kBoth || m_direction == Direction.kForward) {
          RelayJNI.setRelay(m_forwardHandle, false);
        }
        if (m_direction == Direction.kBoth || m_direction == Direction.kReverse) {
          RelayJNI.setRelay(m_reverseHandle, false);
        }
        break;
      case kOn:
        if (m_direction == Direction.kBoth || m_direction == Direction.kForward) {
          RelayJNI.setRelay(m_forwardHandle, true);
        }
        if (m_direction == Direction.kBoth || m_direction == Direction.kReverse) {
          RelayJNI.setRelay(m_reverseHandle, true);
        }
        break;
      case kForward:
        if (m_direction == Direction.kReverse) {
          throw new InvalidValueException("A relay configured for reverse cannot be set to "
              + "forward");
        }
        if (m_direction == Direction.kBoth || m_direction == Direction.kForward) {
          RelayJNI.setRelay(m_forwardHandle, true);
        }
        if (m_direction == Direction.kBoth) {
          RelayJNI.setRelay(m_reverseHandle, false);
        }
        break;
      case kReverse:
        if (m_direction == Direction.kForward) {
          throw new InvalidValueException("A relay configured for forward cannot be set to "
              + "reverse");
        }
        if (m_direction == Direction.kBoth) {
          RelayJNI.setRelay(m_forwardHandle, false);
        }
        if (m_direction == Direction.kBoth || m_direction == Direction.kReverse) {
          RelayJNI.setRelay(m_reverseHandle, true);
        }
        break;
      default:
        // Cannot hit this, limited by Value enum
    }
  }

  /**
   * Get the Relay State.
   *
   * <p>Gets the current state of the relay.
   *
   * <p>When set to kForwardOnly or kReverseOnly, value is returned as kOn/kOff not
   * kForward/kReverse (per the recommendation in Set)
   *
   * @return The current state of the relay as a Relay::Value
   */
  public Value get() {
    if (m_direction == Direction.kForward) {
      if (RelayJNI.getRelay(m_forwardHandle)) {
        return Value.kOn;
      } else {
        return Value.kOff;
      }
    } else if (m_direction == Direction.kReverse) {
      if (RelayJNI.getRelay(m_reverseHandle)) {
        return Value.kOn;
      } else {
        return Value.kOff;
      }
    } else {
      if (RelayJNI.getRelay(m_forwardHandle)) {
        if (RelayJNI.getRelay(m_reverseHandle)) {
          return Value.kOn;
        } else {
          return Value.kForward;
        }
      } else {
        if (RelayJNI.getRelay(m_reverseHandle)) {
          return Value.kReverse;
        } else {
          return Value.kOff;
        }
      }
    }
  }

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

  @Override
  public void setExpiration(double timeout) {
    m_safetyHelper.setExpiration(timeout);
  }

  @Override
  public double getExpiration() {
    return m_safetyHelper.getExpiration();
  }

  @Override
  public boolean isAlive() {
    return m_safetyHelper.isAlive();
  }

  @Override
  public void stopMotor() {
    set(Value.kOff);
  }

  @Override
  public boolean isSafetyEnabled() {
    return m_safetyHelper.isSafetyEnabled();
  }

  @Override
  public void setSafetyEnabled(boolean enabled) {
    m_safetyHelper.setSafetyEnabled(enabled);
  }

  @Override
  public String getDescription() {
    return "Relay ID " + getChannel();
  }

  /**
   * Set the Relay Direction.
   *
   * <p>Changes which values the relay can be set to depending on which direction is used
   *
   * <p>Valid inputs are kBothDirections, kForwardOnly, and kReverseOnly
   *
   * @param direction The direction for the relay to operate in
   */
  public void setDirection(Direction direction) {
    requireNonNull(direction, "Null Direction was given");
    if (m_direction == direction) {
      return;
    }

    freeRelay();
    m_direction = direction;
    initRelay();
  }

  @Override
  public void initSendable(SendableBuilder builder) {
    builder.setSmartDashboardType("Relay");
    builder.setSafeState(() -> set(Value.kOff));
    builder.addStringProperty("Value", () -> get().getPrettyValue(),
        (value) -> set(Value.getValueOf(value).orElse(Value.kOff)));
  }
}