/*--------------------------------------------------------------------------
    *  Copyright 2008 utgenome.org
    *
    *  Licensed under the Apache License, Version 2.0 (the "License");
    *  you may not use this file except in compliance with the License.
    *  You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *--------------------------------------------------------------------------*/
  //--------------------------------------
  // utgb-widget Project
  //
  // Switch.java
  // Since: Apr 24, 2008
  //
  // $URL$ 
  // $Author$
  //--------------------------------------
  package org.utgenome.gwt.widget.client;
  
  import com.google.gwt.user.client.DOM;
  import com.google.gwt.user.client.Element;
  import com.google.gwt.user.client.Event;
  import com.google.gwt.user.client.ui.FocusPanel;
  import com.google.gwt.user.client.ui.Widget;
  
  /**
   * Flip/Flop type widget
   * 
   * @author leo
   * 
   */
  public class Switch extends FocusPanel {
  
  	private Element currentSwitchFace = null;
  
  	private Widget onWidget;
  	private Widget offWidget;
  	private Widget onHoveringWidget;
  	private Widget offHoveringWidget;
  
  	private boolean isOn = false;
  
  	private boolean isFocusing = false;
  	private boolean isCapturing = false;
  	private boolean isHovering = false;
  
  	public Switch(Widget on, Widget onHovering, Widget off, Widget offHovering) {
  		this.onWidget = on;
  		this.offWidget = off;
  		this.onHoveringWidget = onHovering;
  		this.offHoveringWidget = offHovering;
  
  		Style.cursor(this, Style.CURSOR_POINTER);
  		updateSwitchFace(offWidget.getElement());
  	}
  
  	public Switch(Icon on, Icon off) {
  		this(on.getIconImage(), on.getMouseOverIconImage(), off.getIconImage(), off.getMouseOverIconImage());
  	}
  
  	public void setSwitch(boolean on) {
  		isOn = on;
  		updateSwitchFace(isOn ? onWidget.getElement() : offWidget.getElement());
  	}
  
  	private void setHovering(boolean hovering) {
  		this.isHovering = hovering;
  		if (isOn)
  			updateSwitchFace(isHovering ? onHoveringWidget.getElement() : onWidget.getElement());
  		else
  			updateSwitchFace(isHovering ? offHoveringWidget.getElement() : offWidget.getElement());
  	}
  
  	protected void updateSwitchFace(Element newFace) {
  		if (currentSwitchFace != newFace) {
  			if (currentSwitchFace != null)
  				DOM.removeChild(getElement(), currentSwitchFace);
  
  			currentSwitchFace = newFace;
  			DOM.appendChild(getElement(), currentSwitchFace);
  		}
  	}
  
  	/**
  	 * Called when the user finishes clicking on this button. The default behavior is to fire the click event to
  	 * listeners. Subclasses that override {@link #onClickStart()} should override this method to restore the normal
  	 * widget display.
  	 */
  	protected void onClick() {
  
  	}
  
 	/**
 	 * Called when the user aborts a click in progress; for example, by dragging the mouse outside of the button before
 	 * releasing the mouse button. Subclasses that override {@link #onClickStart()} should override this method to
 	 * restore the normal widget display.
 	 */
 	protected void onClickCancel() {
 	}
 
 	/**
 	 * Called when the user begins to click on this button. Subclasses may override this method to display the start of
 	 * the click visually; such subclasses should also override {@link #onClick()} and {@link #onClickCancel()} to
 	 * restore normal visual state. Each <code>onClickStart</code> will eventually be followed by either
 	 * <code>onClick</code> or <code>onClickCancel</code>, depending on whether the click is completed.
 	 */
 	protected void onClickStart() {
 	}
 
 	@Override
 	public void onBrowserEvent(Event event) {
 		// Should not act on button if disabled.
 
 		int type = DOM.eventGetType(event);
 		switch (type) {
 		case Event.ONMOUSEDOWN:
 			isFocusing = true;
 			onClickStart();
 			DOM.setCapture(getElement());
 			isCapturing = true;
 			// Prevent dragging (on some browsers);
 			DOM.eventPreventDefault(event);
 			break;
 		case Event.ONMOUSEUP:
 			if (isCapturing) {
 				isCapturing = false;
 				DOM.releaseCapture(getElement());
 				if (isHovering) {
 					onClick();
 				}
 			}
 			break;
 		case Event.ONMOUSEMOVE:
 			if (isCapturing) {
 				// Prevent dragging (on other browsers);
 				DOM.eventPreventDefault(event);
 			}
 			break;
 		case Event.ONMOUSEOUT:
 			Element to = DOM.eventGetToElement(event);
 			if (DOM.isOrHasChild(getElement(), DOM.eventGetTarget(event)) && (to == null || !DOM.isOrHasChild(getElement(), to))) {
 				if (isCapturing) {
 					onClickCancel();
 				}
 				setHovering(false);
 			}
 			break;
 		case Event.ONMOUSEOVER:
 			if (DOM.isOrHasChild(getElement(), DOM.eventGetTarget(event))) {
 				setHovering(true);
 				if (isCapturing) {
 					onClickStart();
 				}
 			}
 			break;
 		case Event.ONCLICK:
 			// we handle clicks ourselves
 			return;
 		case Event.ONBLUR:
 			if (isFocusing) {
 				isFocusing = false;
 				onClickCancel();
 			}
 			break;
 		case Event.ONLOSECAPTURE:
 			if (isCapturing) {
 				isCapturing = false;
 				onClickCancel();
 			}
 			break;
 		}
 
 		super.onBrowserEvent(event);
 
 		// Synthesize clicks based on keyboard events AFTER the normal key handling.
 		char keyCode = (char) DOM.eventGetKeyCode(event);
 		switch (type) {
 		case Event.ONKEYDOWN:
 			if (keyCode == ' ') {
 				isFocusing = true;
 				onClickStart();
 			}
 			break;
 		case Event.ONKEYUP:
 			if (isFocusing && keyCode == ' ') {
 				isFocusing = false;
 				onClick();
 			}
 			break;
 		case Event.ONKEYPRESS:
 			if (keyCode == '\n' || keyCode == '\r') {
 				onClickStart();
 				onClick();
 			}
 			break;
 		}
 	}
 
 }