package aimax.osm.gps;

import gnu.io.CommPortIdentifier;
import gnu.io.SerialPort;
import gnu.io.SerialPortEvent;
import gnu.io.SerialPortEventListener;

import java.io.File;
import java.io.IOException;
import java.util.Enumeration;

/**
 * Reads GPS data from a NMEA stream via a serial port connection.
 * To compile and run this class, download the rs232 serial port library
 * from http://www.rxtx.org/ and install it correctly.
 * One possibility is, to add the jar-file
 * to the class path (project properties, add jar), to store the DDL
 * locally (e.g. in project-root/lib), and start the application with
 * VM argument <code>-Djava.library.path=lib</code>.
 * @author Ruediger Lunde
 */
public class NmeaSerialPortReader extends NmeaReader {

	public static int TIMEOUT  = 2000; // 2 seconds
	public static int BAUDRATE = 38400;
	private SerialPort sPort;
	private SerialPortEventListener sPortListener;
	private String portname;
	
	public NmeaSerialPortReader() {
		sPortListener = new SerialPortEventListener() {
			public void serialEvent(SerialPortEvent event) {
				if (event.getEventType() == SerialPortEvent.DATA_AVAILABLE) {
					readFromStream(false);
				}
			}
		};
	}
	
	/**
	 * Specifies the name of the serial port to be used for the
	 * next connection to be opened.
	 */
	public void selectPortName(String portname) {
		this.portname = portname;
	}
	
	/**
	 * Returns the name of the selected serial port.
	 */
	public String getSelectedPortName() {
		return portname;
	}
	
	/**
	 * Opens the stream if it is not already open. If no port
	 * name is selected, all serial ports are scanned. 
	 */
	public void openStream() throws Exception {
		if (sPort != null)
			return;
		if (findSerialPort()) {
			sPort.addEventListener(sPortListener);
			sPort.notifyOnDataAvailable(true);
		} else if (portname != null) {
			throw new IOException("Serial port " + portname + " not found.");
		} else {
			throw new IOException("No serial port with NMEA messages found.");
		}	
	}
	
	/** Closes the stream and also the serial port. */
	public void closeStream() throws IOException {
		if (sPort != null) {
			sPort.removeEventListener();
			//sPort.notifyOnDataAvailable(false);
			sPort.close();
			sPort = null;
			super.closeStream();
		}
	}
	
	/** Searches for a serial port providing NMEA messages. */
	private boolean findSerialPort() throws Exception {
		Enumeration<?>  portList = CommPortIdentifier.getPortIdentifiers();
		while (portList.hasMoreElements()) {
			CommPortIdentifier pid = (CommPortIdentifier) portList.nextElement();
			if (pid.getPortType() == CommPortIdentifier.PORT_SERIAL
					&& (portname == null || pid.getName().equals(portname))) {
				sPort = (SerialPort) pid.open("NmeaSerialPortReader", TIMEOUT);
				//System.out.println("\n" + pid.getName());
				sPort.setSerialPortParams(BAUDRATE,
					SerialPort.DATABITS_8,
					SerialPort.STOPBITS_1,
					SerialPort.PARITY_NONE);
				inputStream = sPort.getInputStream();
				Thread.sleep(TIMEOUT);
				int avail = inputStream.available();
				if (avail > 0) {
					//Thread.sleep(TIMEOUT);
					StringBuffer buffer = new StringBuffer();
					int value;
					while ((value = inputStream.read()) != -1 && buffer.length() < 500) {
						buffer.append((char) value);
					}
					//System.out.println(sPort.getName() + ": " + buffer.toString() + "\n");
					if (buffer.toString().contains("$GPGGA")) {
						portname = pid.getName();
						return true;
					}
				}
				sPort.close();
				sPort = null;
			}
		}
		return false;
	}
	
	/////////////////////////////////////////////////////////////////
	// Simple test program...
	
	public static void main(String[] args) {
		try {
			NmeaSerialPortReader reader = new NmeaSerialPortReader();
			reader.openStream();
			
			NmeaMessageListener consoleLogger = new NmeaMessageListener() {
				public void messageReceived(String buffer) {
					System.out.print(buffer);
				}
			};
			MessageToFileListener fileLogger = new MessageToFileListener();
			reader.addListener(consoleLogger);
			reader.addListener(fileLogger);
			fileLogger.openFile(new File("nmeaout.txt"));
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}