// Simple applet illustrating use of add/removeChildren fields.

import java.awt.*;
import java.applet.*;
import vrml.external.field.*;
import vrml.external.Node;
import vrml.external.Browser;
import vrml.external.exception.*;
import netscape.javascript.JSObject;

public class AddRemoveTest extends Applet {
  TextArea output = null;
  boolean error = false;

  // Browser we're using
  Browser browser;
  // Root of the scene graph (to which we add our nodes)
  Node root;
  // Shape group hierarchy
  Node[] shape;

  // EventIns of the root node
  EventInMFNode addChildren;
  EventInMFNode removeChildren;

  public void init() {
    add(new Button("Add Sphere"));
    add(new Button("Remove Sphere"));

    output = new TextArea(5, 40);
    add(output);

    JSObject win = JSObject.getWindow(this);
    JSObject doc = (JSObject) win.getMember("document");
    JSObject embeds = (JSObject) doc.getMember("embeds");
    browser = (Browser) embeds.getSlot(0);

    try {
      // Get root node of the scene, and its EventIns
      root = browser.getNode("ROOT");
      addChildren = (EventInMFNode) root.getEventIn("addChildren");
      removeChildren = (EventInMFNode) root.getEventIn("removeChildren");

      // Instantiate our ubiquitous blue sphere hierarchy
      shape = browser.createVrmlFromString("Shape {\n" +
					   "  appearance Appearance {\n" +
					   "    material Material {\n" +
					   "      diffuseColor 0.2 0.2 0.8\n" +
					   "    }\n" +
					   "  }\n" +
					   "  geometry Sphere {}\n" +
					   "}\n");
    }
    catch (InvalidNodeException e) {
      output.appendText("PROBLEMS!: " + e + "\n");
      error = true;
    }
    catch (InvalidEventInException e) {
      output.appendText("PROBLEMS!: " + e + "\n");
      error = true;
    }
    catch (InvalidVrmlException e) {
      output.appendText("PROBLEMS!: " + e + "\n");
      error = true;
    }
      
    if (error == false)
      output.appendText("Ok...\n");
  }

  public boolean action(Event event, Object what) {
    if (event.target instanceof Button) {
      Button b = (Button) event.target;
      if (b.getLabel() == "Add Sphere") {
	addChildren.setValue(shape);
	
      }
      else if (b.getLabel() == "Remove Sphere") {
	removeChildren.setValue(shape);
      }
    }
    return true;
  }
}