import uwcse.graphics.*;
import java.awt.Point;
import java.util.*;
import java.awt.Color;

/**
 * representation and display of a caterpillar
 */

public class Caterpillar implements CaterpillarConstants
{
    // The body of a caterpillar is made of Points stored
    // in an ArrayList
    private ArrayList body = new ArrayList();

    // Store the graphical elements of the caterpillar body
    // Useful to erase the body of the caterpillar on the screen
    private ArrayList bodyUnits = new ArrayList();

    // The window the caterpillar belongs to
    private GWindow window;

    // Direction of motion of the caterpillar (NORTH initially)
    private int dir = NORTH;

    // Length of a unit of the body of the caterpillar
    // MUST be equal to the distance covered by the caterpillar
    // at every step of the animation.
    private final int bodyUnitLength=STEP;
    // Width of a unit of the body of the caterpillar
    private final int bodyUnitWidth=CATERPILLAR_WIDTH;

    /**
     * Construct a caterpillar
     */
    public Caterpillar(GWindow window)
    {
        // Initialize the graphics window for this Caterpillar
        this.window = window;

        // Create the caterpillar (10 points)
        // First point

        // Other points

        // Show the caterpillar
        draw();
    }


    /**
     * Draw the caterpillar in the graphics window
     */
    private void draw()
    {
        // Connect the points of the body in the graphics window
        // (use lines, or rectangles...)
    }


    /**
     * Move the caterpillar in the current direction
     */
    public void move()
    {
        move(dir);
    }

    /**
     * Move the caterpillar in the direction newDir. <br>
     * If the new direction is illegal, select a
     * legal direction of motion and move in that direction.<br>
     */
    public void move(int newDir)
    {
        // Is the move illegal?
        boolean isMoveNotOK;

        // newDir might not be legal
        // Before trying a random direction, try first
        // the current direction of motion (if not newDir)
        boolean isFirstTry = true;

        // move the caterpillar in direction newDir
        do{
            // new position of the head
            Point head;

            // Is the new position in the window?
            if (isPointInTheWindow(head))
            {
                // update the position of the caterpillar
            }
            else
            {
                // Select another direction
            }
        }while(isMoveNotOK);

        // Update the current direction of motion
        dir = newDir;

        // Show the new location of the caterpillar
        moveCaterpillarOnScreen();
    }

    /**
     * Move the caterpillar on the screen
     */
    private void moveCaterpillarOnScreen()
    {
        // Erase the body unit at the tail

        // Add a new body unit at the head

        // show it
        window.doRepaint();
    }

    /**
     * Add a body unit to the caterpillar. The body unit
     * connects Point p and Point q.<br>
     * Insert this body unit at position index in bodyUnits.<br>
     * e.g. 0 to insert at the tail and bodyUnits.size() to insert
     * at the head.
     */
    private void addBodyUnit(Point p, Point q, int index)
    {
        // Connect p and q with your preferred graphics element
    }


    /**
     * Is Point p in the window?
     */
    private boolean isPointInTheWindow(Point p)
    {
    }
}