// linebot_modified.nqc
//	line tracking tracking algorithm

// sensor and motors
#define EYE		SENSOR_2
#define LEFT	OUT_A
#define RIGHT	OUT_C

// constants
#define LINE_THRESHOLD 36
#define TURN_SPEED 7
#define INITIAL_TIME 4

int direction, time, eye;


task main()
{
	SetSensor(EYE, SENSOR_LIGHT);

  // initialize the variables
	direction = 1;
	time = INITIAL_TIME;

	// start driving
	OnFwd(LEFT+RIGHT);

	while(true)
	{
		// read the sensor value
		eye = EYE;

		 if (eye > LINE_THRESHOLD)
		 {
      ClearTimer(0);
			if (direction == 1)
			{
				SetPower(RIGHT+LEFT, TURN_SPEED);
				Rev(LEFT);
			}
			else
			{
				SetPower(RIGHT+LEFT, TURN_SPEED);
				Rev(RIGHT);
			}

			while(true)
			{
				// have we found the line?
				if (EYE < LINE_THRESHOLD)
				{
					time = INITIAL_TIME;
					break;
				}

				if (Timer(0) > time)
				{
					// try the other direction
					direction = -direction;
					time = 2*time;
					break;
				}
			}

			SetPower(RIGHT+LEFT, OUT_FULL);
			Fwd(RIGHT+LEFT);
		}
	}

}