import java.awt.event.KeyEvent;
import java.util.LinkedList;

public class Snake {

    private int headX;
    private int headY;

    private Cell[][] grid;

    LinkedList<Cell> snakeCells;

    private int length;
    private SnakePanel parent;
    private int direction = KeyEvent.VK_RIGHT;

    public Snake(SnakePanel parent) {
        this.parent = parent;
        this.grid = parent.getGrid();

        length = 3;
        headX = parent.sizeX / 2;
        headY = parent.sizeY / 2;

        snakeCells = new LinkedList<Cell>();

        grid[headY][headX].setType(CellType.SNAKE);
        snakeCells.addFirst(grid[headX][headY]);
    }

    public int getDirection() {
        return direction;
    }

    public void setDirection(int direction) {
        this.direction = direction;
    }

    public void performMove() {
        switch (direction) {
            case (KeyEvent.VK_RIGHT):
                headX++;
                break;

            case (KeyEvent.VK_LEFT):
                headX--;
                break;

            case (KeyEvent.VK_UP):
                headY--;
                break;

            case (KeyEvent.VK_DOWN):
                headY++;
                break;
        }

        if (headX < 0 || headY < 0 || headY >= parent.sizeY || headX >= parent.sizeX) {
            parent.gameOver();
            return;
        }

        Cell newCell = grid[headY][headX];

        if (newCell == null || newCell.getType() == CellType.SNAKE) {
            parent.gameOver();
            return;
        } else if (newCell.getType() == CellType.FRUIT) {
            length++;
            parent.makeFruit();
        }

        snakeCells.addFirst(newCell);
        newCell.setType(CellType.SNAKE);
        newCell.repaint();

        if (snakeCells.size() > length) {
            Cell c = snakeCells.removeLast();
            c.setType(CellType.EMPTY);
            c.repaint();
        }
    }
}