/*----------------------------------------------------------------------------*/
/* 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.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;

import edu.wpi.first.wpilibj.hal.FRCNetComm.tResourceType;
import edu.wpi.first.wpilibj.hal.HAL;
import edu.wpi.first.wpilibj.hal.SerialPortJNI;

/**
 * Driver for the RS-232 serial port on the roboRIO.
 *
 * <p>The current implementation uses the VISA formatted I/O mode. This means that all traffic goes
 * through the formatted buffers. This allows the intermingled use of print(), readString(), and the
 * raw buffer accessors read() and write().
 *
 * <p>More information can be found in the NI-VISA User Manual here: http://www.ni
 * .com/pdf/manuals/370423a.pdf and the NI-VISA Programmer's Reference Manual here:
 * http://www.ni.com/pdf/manuals/370132c.pdf
 */
public class SerialPort {

  private byte m_port;

  public enum Port {
    kOnboard(0), kMXP(1), kUSB(2), kUSB1(2), kUSB2(3);

    @SuppressWarnings("MemberName")
    public int value;

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

  /**
   * Represents the parity to use for serial communications.
   */
  public enum Parity {
    kNone(0), kOdd(1), kEven(2), kMark(3), kSpace(4);

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

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

  /**
   * Represents the number of stop bits to use for Serial Communication.
   */
  public enum StopBits {
    kOne(10), kOnePointFive(15), kTwo(20);

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

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

  /**
   * Represents what type of flow control to use for serial communication.
   */
  public enum FlowControl {
    kNone(0), kXonXoff(1), kRtsCts(2), kDtsDsr(4);

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

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

  /**
   * Represents which type of buffer mode to use when writing to a serial m_port.
   */
  public enum WriteBufferMode {
    kFlushOnAccess(1), kFlushWhenFull(2);

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

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

  /**
   * Create an instance of a Serial Port class.
   *
   * @param baudRate The baud rate to configure the serial port.
   * @param port     The Serial port to use
   * @param dataBits The number of data bits per transfer. Valid values are between 5 and 8 bits.
   * @param parity   Select the type of parity checking to use.
   * @param stopBits The number of stop bits to use as defined by the enum StopBits.
   */
  public SerialPort(final int baudRate, Port port, final int dataBits, Parity parity,
                    StopBits stopBits) {
    m_port = (byte) port.value;

    SerialPortJNI.serialInitializePort(m_port);
    SerialPortJNI.serialSetBaudRate(m_port, baudRate);
    SerialPortJNI.serialSetDataBits(m_port, (byte) dataBits);
    SerialPortJNI.serialSetParity(m_port, (byte) parity.value);
    SerialPortJNI.serialSetStopBits(m_port, (byte) stopBits.value);

    // Set the default read buffer size to 1 to return bytes immediately
    setReadBufferSize(1);

    // Set the default timeout to 5 seconds.
    setTimeout(5.0);

    // Don't wait until the buffer is full to transmit.
    setWriteBufferMode(WriteBufferMode.kFlushOnAccess);

    disableTermination();

    HAL.report(tResourceType.kResourceType_SerialPort, 0);
  }

  /**
   * Create an instance of a Serial Port class. Defaults to one stop bit.
   *
   * @param baudRate The baud rate to configure the serial port.
   * @param dataBits The number of data bits per transfer. Valid values are between 5 and 8 bits.
   * @param parity   Select the type of parity checking to use.
   */
  public SerialPort(final int baudRate, Port port, final int dataBits, Parity parity) {
    this(baudRate, port, dataBits, parity, StopBits.kOne);
  }

  /**
   * Create an instance of a Serial Port class. Defaults to no parity and one stop bit.
   *
   * @param baudRate The baud rate to configure the serial port.
   * @param dataBits The number of data bits per transfer. Valid values are between 5 and 8 bits.
   */
  public SerialPort(final int baudRate, Port port, final int dataBits) {
    this(baudRate, port, dataBits, Parity.kNone, StopBits.kOne);
  }

  /**
   * Create an instance of a Serial Port class. Defaults to 8 databits, no parity, and one stop
   * bit.
   *
   * @param baudRate The baud rate to configure the serial port.
   */
  public SerialPort(final int baudRate, Port port) {
    this(baudRate, port, 8, Parity.kNone, StopBits.kOne);
  }

  /**
   * Destructor.
   */
  public void free() {
    SerialPortJNI.serialClose(m_port);
  }

  /**
   * Set the type of flow control to enable on this port.
   *
   * <p>By default, flow control is disabled.
   *
   * @param flowControl the FlowControl m_value to use
   */
  public void setFlowControl(FlowControl flowControl) {
    SerialPortJNI.serialSetFlowControl(m_port, (byte) flowControl.value);
  }

  /**
   * Enable termination and specify the termination character.
   *
   * <p>Termination is currently only implemented for receive. When the the terminator is received,
   * the read() or readString() will return fewer bytes than requested, stopping after the
   * terminator.
   *
   * @param terminator The character to use for termination.
   */
  public void enableTermination(char terminator) {
    SerialPortJNI.serialEnableTermination(m_port, terminator);
  }

  /**
   * Enable termination with the default terminator '\n'
   *
   * <p>Termination is currently only implemented for receive. When the the terminator is received,
   * the read() or readString() will return fewer bytes than requested, stopping after the
   * terminator.
   *
   * <p>The default terminator is '\n'
   */
  public void enableTermination() {
    enableTermination('\n');
  }

  /**
   * Disable termination behavior.
   */
  public void disableTermination() {
    SerialPortJNI.serialDisableTermination(m_port);
  }

  /**
   * Get the number of bytes currently available to read from the serial port.
   *
   * @return The number of bytes available to read.
   */
  public int getBytesReceived() {
    return SerialPortJNI.serialGetBytesRecieved(m_port);
  }

  /**
   * Read a string out of the buffer. Reads the entire contents of the buffer
   *
   * @return The read string
   */
  public String readString() {
    return readString(getBytesReceived());
  }

  /**
   * Read a string out of the buffer. Reads the entire contents of the buffer
   *
   * @param count the number of characters to read into the string
   * @return The read string
   */
  public String readString(int count) {
    byte[] out = read(count);
    try {
      return new String(out, 0, out.length, "US-ASCII");
    } catch (UnsupportedEncodingException ex) {
      ex.printStackTrace();
      return "";
    }
  }

  /**
   * Read raw bytes out of the buffer.
   *
   * @param count The maximum number of bytes to read.
   * @return An array of the read bytes
   */
  public byte[] read(final int count) {
    ByteBuffer dataReceivedBuffer = ByteBuffer.allocateDirect(count);
    int gotten = SerialPortJNI.serialRead(m_port, dataReceivedBuffer, count);
    byte[] retVal = new byte[gotten];
    dataReceivedBuffer.get(retVal);
    return retVal;
  }

  /**
   * Write raw bytes to the serial port.
   *
   * @param buffer The buffer of bytes to write.
   * @param count  The maximum number of bytes to write.
   * @return The number of bytes actually written into the port.
   */
  public int write(byte[] buffer, int count) {
    ByteBuffer dataToSendBuffer = ByteBuffer.allocateDirect(count);
    dataToSendBuffer.put(buffer, 0, count);
    return SerialPortJNI.serialWrite(m_port, dataToSendBuffer, count);
  }

  /**
   * Write a string to the serial port
   *
   * @param data The string to write to the serial port.
   * @return The number of bytes actually written into the port.
   */
  public int writeString(String data) {
    return write(data.getBytes(), data.length());
  }

  /**
   * Configure the timeout of the serial m_port.
   *
   * <p>This defines the timeout for transactions with the hardware. It will affect reads if less
   * bytes are available than the read buffer size (defaults to 1) and very large writes.
   *
   * @param timeout The number of seconds to to wait for I/O.
   */
  public void setTimeout(double timeout) {
    SerialPortJNI.serialSetTimeout(m_port, timeout);
  }

  /**
   * Specify the size of the input buffer.
   *
   * <p>Specify the amount of data that can be stored before data from the device is returned to
   * Read. If you want data that is received to be returned immediately, set this to 1.
   *
   * <p>It the buffer is not filled before the read timeout expires, all data that has been received
   * so far will be returned.
   *
   * @param size The read buffer size.
   */
  public void setReadBufferSize(int size) {
    SerialPortJNI.serialSetReadBufferSize(m_port, size);
  }

  /**
   * Specify the size of the output buffer.
   *
   * <p>Specify the amount of data that can be stored before being transmitted to the device.
   *
   * @param size The write buffer size.
   */
  public void setWriteBufferSize(int size) {
    SerialPortJNI.serialSetWriteBufferSize(m_port, size);
  }

  /**
   * Specify the flushing behavior of the output buffer.
   *
   * <p>When set to kFlushOnAccess, data is synchronously written to the serial port after each
   * call to either print() or write().
   *
   * <p>When set to kFlushWhenFull, data will only be written to the serial port when the buffer
   * is full or when flush() is called.
   *
   * @param mode The write buffer mode.
   */
  public void setWriteBufferMode(WriteBufferMode mode) {
    SerialPortJNI.serialSetWriteMode(m_port, (byte) mode.value);
  }

  /**
   * Force the output buffer to be written to the port.
   *
   * <p>This is used when setWriteBufferMode() is set to kFlushWhenFull to force a flush before the
   * buffer is full.
   */
  public void flush() {
    SerialPortJNI.serialFlush(m_port);
  }

  /**
   * Reset the serial port driver to a known state.
   *
   * <p>Empty the transmit and receive buffers in the device and formatted I/O.
   */
  public void reset() {
    SerialPortJNI.serialClear(m_port);
  }
}