// SpriteVector Class
// SpriteVector.java

// Imports
import java.awt.*;
import java.util.*;

public class SpriteVector extends Vector {
  Component component;
  Image     background;

  SpriteVector() {
    super(50, 10);
  }

  SpriteVector(Component comp, Image bg) {
    super(50, 10);
    component = comp;
    background = bg;
  }

  Image getBackground() {
    return background;
  }

  void setBackground(Image back) {
    background = back;
  }

  void update() {
    Sprite    s, hit;
    Rectangle old;
    int       size = size();

    // Iterate through sprites, updating each
    for (int i = 0; i < size; i++) {
      s = (Sprite)elementAt(i);
      old = s.getPositionRect();
      s.update();
      hit = testCollision(s);
      if (hit != null) {
        s.setPosition(old);
        collision(s, hit);
      }
    }
  }

  void draw(Graphics g) {
    if (background != null)
      // Draw background image
      g.drawImage(background, 0, 0, component);
    else {
      // Erase background
      Dimension dim = component.size();
      g.setColor(component.getBackground());
      g.fillRect(0, 0, dim.width, dim.height);
      g.setColor(Color.black);
    }

    // Iterate through sprites, drawing each
    int size = size();
    for (int i = 0; i < size; i++)
      ((Sprite)elementAt(i)).draw(g);
  }

  int add(Sprite s) {
    // Use a binary search to find the right location to insert the
    // new sprite (based on z-order)
    int   l = 0, r = size(), x = 0;
    int   z = s.getZOrder(),
          zTest = z + 1;
    while (r > l) {
      x = (l + r) / 2;
      zTest = ((Sprite)elementAt(x)).getZOrder();
      if (z < zTest)
        r = x;
      else
        l = x + 1;
      if (z == zTest)
        break;
    }
    if (z >= zTest)
      x++;

    insertElementAt(s, x);
    return x;
  }

  Sprite testCollision(Sprite test) {
    // Check for collision with other sprites
    int     size = size();
    Sprite  s;
    for (int i = 0; i < size; i++)
    {
      s = (Sprite)elementAt(i);
      if (s == test)  // don't check itself
        continue;
      if (test.testCollision(s))
        return s;
    }
    return null;
  }

  protected void collision(Sprite s, Sprite hit) {
    // Swap velocities (bounce)
    Point swap = s.getVelocity();
    s.setVelocity(hit.getVelocity());
    hit.setVelocity(swap);
  }
}