package stamp.peripheral.gps;
import stamp.core.*;

public class GPS_Parallax { //class for Parallax GPS receiver module (stock #28146)
                            //currently only smart mode is supported

  private static final int GetInfo  = 0x00;
  private static final int GetValid = 0x01;
  private static final int GetSats  = 0x02;
  private static final int GetTime  = 0x03;
  private static final int GetDate  = 0x04;
  private static final int GetLat   = 0x05;
  private static final int GetLong  = 0x06;
  private static final int GetAlt   = 0x07;
  private static final int GetSpeed = 0x08;
  private static final int GetHead  = 0x09;

  private Uart rx;
  private int modePin;
  private boolean smartMode = true;
  private char[] buf = new char[5];

  //public results for fast access (read only)
  public static int hours,minutes,seconds;
  public static int day,month,year;
  public static int latDegrees,latMinutes,latFracmin,latDirection;
  public static int lngDegrees,lngMinutes,lngFracmin,lngDirection;

  /**
   * Constructor
   *
   * @param rx Receive uart (also used for transmission of command)
   * @param modePin Pin used to select smart or raw mode (use 0 if modepin not used)
   */
  public GPS_Parallax(Uart rx, int modePin) {
    this.rx = rx;
    this.modePin = modePin;
  }

/*
Cmd   Constant  Description               Returned Bytes   Variables (1 Byte Each Unless Noted)
0x00  GetInfo   GPS Receiver Module version            2   Hardware, Firmware
0x01  GetValid  Check validity of data string          1   0 = Not Valid, 1 = Valid
0x02  GetSats   Number of acquired satellites
                (12 maximum)                           1
0x03  GetTime   Time (UTC/Greenwich Mean Time)         3   Hours, Minutes, Seconds
0x04  GetDate   Date (UTC/Greenwich Mean Time)         3   Day, Month, Year
0x05  GetLat    Latitude                               5   Degrees, Minutes, Fractional Minutes (Word), Direction (0 = N, 1 = S)
0x06  GetLong   Longitude                              5   Degrees, Minutes, Fractional Minutes (Word), Direction (0 = E, 1 = W)
0x07  GetAlt    Altitude above mean-sea-level
                (in tenths of meters, 65535 maximum)   2   Altitude (Word)
0x08  GetSpeed  Speed (in tenths of knots)             2   Speed (Word)
0x09  GetHead   Heading/direction of travel
                (in tenths of degrees)                 2   Heading (Word)
*/

  public int getInfo() {
    smartRequest(GetInfo,2);
    return assembleWord(); //hardware in lowbyte, firmware in highbyte
  }

  public boolean getValid() {
    smartRequest(GetValid,1);
    return (buf[0] == 0) ? false : true;
  }

  public int getSats() {
    smartRequest(GetSats,1);
    return buf[0]&0xFF;
  }

  public String getTime() {
    StringBuffer time = new StringBuffer(32);
    smartRequest(GetTime,3);
    hours = buf[0]&0xFF;
    minutes = buf[1]&0xFF;
    seconds = buf[2]&0xFF;
    time.append(hours);
    time.append(':');
    time.append(minutes);
    time.append(':');
    time.append(seconds);

    return time.toString();
  }


  public void getDate() {
    smartRequest(GetDate,3);
    day = buf[0]&0xFF;
    month = buf[1]&0xFF;
    year = buf[2]&0xFF;
  }

  public int getLatDegrees() {
    smartRequest(GetLat,5);
    latDegrees = buf[0]&0xFF;
    return latDegrees;
    }

  public int getLatMinutes() {
    smartRequest(GetLat,5);
    latMinutes = buf[1]&0xFF;
    return latMinutes;
    }

  public int getLatFracmin() {
    smartRequest(GetLat,5);
    latFracmin = (buf[2]&0xFF)|(buf[3]<<8);
    return latFracmin;
    }

  public int getLatDirection() {
    smartRequest(GetLat,5);
    latDirection = buf[4]&0xFF;
    return latDirection;
    }

  public int getLongDegrees() {
    smartRequest(GetLong,5);
    lngDegrees = buf[0]&0xFF;
    return lngDegrees;
    }

  public int getLongMinutes() {
    smartRequest(GetLong,5);
    lngMinutes = buf[1]&0xFF;
    return lngMinutes;
    }

  public int getLongFracmin() {
    smartRequest(GetLong,5);
    lngFracmin = (buf[2]&0xFF)|(buf[3]<<8);
    return lngFracmin;
    }

  public int getLongDirection() {
    smartRequest(GetLong,5);
     lngDirection = buf[4]&0xFF;
    return lngDirection;
    }

  public int getAlt() {
    smartRequest(GetAlt,2);
    return assembleWord();
  }

  public int getSpeed() {
    smartRequest(GetSpeed,2);
    return assembleWord();
  }

  public int getHead() {
    smartRequest(GetHead,2);
    return assembleWord();
  }

  private void smartRequest(int cmd, int response) {
    int i=0;
    if (modePin != 0) CPU.setInput(modePin); //enter smart mode
    rx.setDirection(Uart.dirTransmit); //prepare for transmit
    rx.sendByte('!');
    rx.sendByte('G');
    rx.sendByte('P');
    rx.sendByte('S');
    rx.sendByte(cmd);
    while (!rx.sendBufferEmpty()) ;  //wait for transmit buffer to be empty and nothing is sent
    rx.setDirection(Uart.dirReceive); //prepare for receive
    while (i<response) {
      buf[i++] = (char)rx.receiveByte();
    }
  }

  private int assembleWord() {
    return (buf[0]&0xFF)|(buf[1]<<8);
  }

} 