import josx.platform.rcx.*;

class LineFollower implements SensorConstants
{

// 45 white
// 30 black
// White = Higher percentage
  public static void main (String[] aArg)
  throws Exception
  {
    Sensor.S1.setTypeAndMode(SensorConstants.SENSOR_TYPE_LIGHT,
                             SensorConstants.SENSOR_MODE_PCT);
    Sensor.S1.activate();
    Sensor.S3.setTypeAndMode(SensorConstants.SENSOR_TYPE_LIGHT,
                             SensorConstants.SENSOR_MODE_PCT);
    Sensor.S3.activate();
    int leftSensor=0;
    int rightSensor=0;
    int lastTime=0;
    int blackReading=100;
    int whiteReading=0;
	int avgReading=0;
	
	// Calibrate the line sensors
 	Button runButton = Button.RUN;
 	int breakOut=0;
    while(breakOut==0)
    {
        leftSensor = Sensor.S3.readValue();
        rightSensor = Sensor.S1.readValue();
        // Just use the left sensor for the calibration
        if (leftSensor<blackReading)
        {
        	blackReading=leftSensor;
        }
        if (leftSensor>whiteReading)
        {
        	whiteReading=leftSensor;
        }
        LCD.showNumber(whiteReading);
		if (runButton.isPressed())
		{
			breakOut=1;
		}
    }
    avgReading = ((whiteReading - blackReading)/2) + blackReading;
    LCD.showNumber(avgReading);

	// Delay for five seconds
    try{Thread.sleep(5000);}catch(Exception e){}
    
     Motor.A.forward();
     Motor.C.forward();
     
     // Loop forever
     while (true){
        leftSensor = Sensor.S3.readValue();
        rightSensor = Sensor.S1.readValue();

        if (leftSensor > avgReading && rightSensor > avgReading)
        {
        	// Both Sensors see the white line
		    LCD.showNumber(1);
            Motor.A.setPower(7);
            Motor.C.setPower(7);
        	Motor.A.forward();
        	Motor.C.forward();
        }else
        {
		    LCD.showNumber(0);
        	// Is the Line lost?
            if (leftSensor < avgReading && rightSensor < avgReading)
            {
            	// The line is gone
            	// Need to decide where the line was last
                if (lastTime==0)
                {
                	// Line was last seen on the left
                	// go left
                	Motor.A.stop();
                    Motor.C.setPower(1);
		        	Motor.C.forward();
		        	rightSensor = Sensor.S1.readValue();
				    while (rightSensor<avgReading){
			        	rightSensor = Sensor.S1.readValue();
				    }
                }
                else
                {
                	// Line was last seen on the right
                	// go right
                	Motor.C.stop();
                    Motor.A.setPower(1);
		        	Motor.A.forward();
			        leftSensor = Sensor.S3.readValue();
				    while (leftSensor<avgReading){
				        leftSensor = Sensor.S3.readValue();
				    }
                }
            }else
            {
                if (leftSensor > avgReading)
                {
                    lastTime = 0;
                    Motor.C.setPower(1);
                    Motor.A.setPower(7);
		        	Motor.A.forward();
        			Motor.C.forward();
                }
                if (rightSensor > avgReading)
                {
                    lastTime = 1;
                    Motor.A.setPower(1);
                    Motor.C.setPower(7);
		        	Motor.A.forward();
        			Motor.C.forward();
                }
            }
        }
    }

  }
}
class LineFollowBot implements SensorConstants
{
  public void LineFollowBot(){
        Sensor.S1.setTypeAndMode(SensorConstants.SENSOR_TYPE_LIGHT,
                                 SensorConstants.SENSOR_MODE_PCT);
        Sensor.S1.activate();
        Sensor.S3.setTypeAndMode(SensorConstants.SENSOR_TYPE_LIGHT,
                                 SensorConstants.SENSOR_MODE_PCT);
        Sensor.S3.activate();
  }
  public boolean isBright(){
      if (Sensor.S3.readValue() > 40)
      {
          return true;
      }
      else
      {
          return false;
      }
  }
}