Car.java

package model;

/**
 * Represent a car in the game. The car can be either horizontal or vertical.
 * Also manage movement for that car.
 * For horizontal cars the front is to the right, for vertical cars it is to the bottom of the matrix.
 */
public class Car
{
	private int number;
	private Position front, back;
	private Orientation orientation;

	/**
	 * Create a new car. Front and back are switched if necessary so that the from is to the right and the bottom.
	 */
	public Car(int number, Position front, Position back, Orientation orientation)
	{
		this.number = number;
		this.orientation = orientation;
		if (orientation == Orientation.HORIZONTAL)
		{
			if (back.getX() < front.getX())
			{
				this.back = back;
				this.front = front;
			} else
			{
				this.back = front;
				this.front = back;
			}
		} else
		{
			if (back.getY() < front.getY())
			{
				this.back = back;
				this.front = front;
			} else
			{
				this.back = front;
				this.front = back;
			}
		}
	}

	/**
	 * Move the car forward
	 *
	 * @param board   the board on which apply the changes
	 * @param nbSteps the number of steps this car will move
	 * @throws RuntimeException If the number of steps is too high
	 */
	public void moveForward(int[][] board, int nbSteps) throws RuntimeException
	{
		if (!canMoveForward(board, nbSteps))
			throw new RuntimeException("Illegal number of steps!");
		if (orientation == Orientation.HORIZONTAL)
		{
			for (int i = 0; i < nbSteps; i++)
			{
				board[front.getX() + i + 1][front.getY()] = this.number;
				board[back.getX() + i][back.getY()] = -1;
			}
			front.setX(front.getX() + nbSteps);
			back.setX(back.getX() + nbSteps);
		} else
		{
			for (int i = 0; i < nbSteps; i++)
			{
				board[front.getX()][front.getY() + i + 1] = this.number;
				board[back.getX()][back.getY() + i] = -1;
			}
			front.setY(front.getY() + nbSteps);
			back.setY(back.getY() + nbSteps);
		}
	}

	/**
	 * Move the car backwards
	 *
	 * @param board   the board on which apply the changes
	 * @param nbSteps the number of steps this car will move
	 * @throws RuntimeException If the number of steps is too high
	 */
	public void moveBackwards(int[][] board, int nbSteps) throws RuntimeException
	{
		if (!canMoveBackwards(board, nbSteps))
			throw new RuntimeException("Illegal number of steps!");
		if (orientation == Orientation.HORIZONTAL)
		{
			for (int i = 0; i < nbSteps; i++)
			{
				board[back.getX() - i - 1][back.getY()] = this.number;
				board[front.getX() - i][front.getY()] = -1;
			}
			front.setX(front.getX() - nbSteps);
			back.setX(back.getX() - nbSteps);
		} else
		{
			for (int i = 0; i < nbSteps; i++)
			{
				board[back.getX()][back.getY() - i - 1] = this.number;
				board[front.getX()][front.getY() - i] = -1;
			}
			front.setY(front.getY() - nbSteps);
			back.setY(back.getY() - nbSteps);
		}
	}

	/**
	 * @param board The game board.
	 * @return How many tiles the car can move forward
	 */
	public int getNbStepsForward(int[][] board)
	{
		int result = 0;
		if (this.orientation == Orientation.HORIZONTAL)
			for (int x = this.front.getX() + 1; (x < board.length) && (board[x][this.front.getY()] == -1); x++)
				result++;
		else
			for (int y = this.front.getY() + 1; (y < board.length) && (board[this.front.getX()][y] == -1); y++)
				result++;
		return result;
	}


	/**
	 * @param board The game board.
	 * @return How many tiles the car can move backwards
	 */
	public int getNbStepsBackwards(int[][] board)
	{
		int result = 0;
		if (this.orientation == Orientation.HORIZONTAL)
			for (int x = this.back.getX() - 1; (x > 0) && (board[x][this.back.getY()] == -1); x--)
				result++;
		else
			for (int y = this.back.getY() - 1; (y > 0) && (board[this.back.getX()][y] == -1); y--)
				result++;
		return result;
	}

	/**
	 * Tell if the car can move forward that many steps
	 *
	 * @param board   The game board
	 * @param nbSteps The number of steps
	 */
	public boolean canMoveForward(int[][] board, int nbSteps)
	{
		if (this.orientation == Orientation.HORIZONTAL)
		{
			if (this.front.getX() + nbSteps >= board.length)
				return false;
			for (int x = this.front.getX() + 1; x - this.front.getX() <= nbSteps; x++)
				if (board[x][this.front.getY()] != -1)
					return false;
			return true;
		} else
		{
			if (this.front.getY() + nbSteps >= board.length)
				return false;
			for (int y = this.front.getY() + 1; y - this.front.getY() <= nbSteps; y++)
				if (board[this.front.getX()][y] != -1)
					return false;
			return true;
		}
	}


	/**
	 * Tell if the car can move backwards that many steps
	 *
	 * @param board   The game board
	 * @param nbSteps The number of steps
	 */
	public boolean canMoveBackwards(int[][] board, int nbSteps)
	{
		if (this.orientation == Orientation.HORIZONTAL)
		{
			if (this.back.getX() - nbSteps < 0)
				return false;
			for (int x = this.back.getX() - 1; this.back.getX() - x <= nbSteps; x--)
				if (board[x][this.back.getY()] != -1)
					return false;
			return true;
		} else
		{
			if (this.back.getY() - nbSteps < 0)
				return false;
			for (int y = this.back.getY() - 1; this.back.getY() - y <= nbSteps; y--)
				if (board[this.back.getX()][y] != -1)
					return false;
			return true;
		}
	}

	public Position getFront()
	{
		return front;
	}

	public Position getBack()
	{
		return back;
	}

	public Orientation getOrientation()
	{
		return orientation;
	}

	public int getNumber()
	{
		return number;
	}

	public static enum Orientation
	{
		HORIZONTAL, VERTICAL;
	}

}