/**********************************************
    * Copyright (C) 2009 Lukas Laag
    * This file is part of Vectomatic.
    * 
    * Vectomatic is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    * 
   * Vectomatic is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   * 
   * You should have received a copy of the GNU General Public License
   * along with Vectomatic.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.client.rep.view;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.vectomatic.client.rep.controller.ColorEditor;
  import org.vectomatic.common.events.IPaletteListener;
  import org.vectomatic.common.model.style.Color;
  import org.vectomatic.common.model.style.Palette;
  
  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.ChangeListener;
  import com.google.gwt.user.client.ui.ChangeListenerCollection;
  import com.google.gwt.user.client.ui.SourcesChangeEvents;
  import com.google.gwt.user.client.ui.Widget;
  
  /**
   * Widget class to represent a palette
   */
  public class PaletteWidget extends Widget implements IPaletteListener, ChangeListener, SourcesChangeEvents {
  	private Palette _palette;
  	private int _selectedColorIndex;
  	private int _columnCount;
  	private int _divWidth;
  	private int _divHeight;
  	private int _margin;
  	private List<Element> _subdivs;
  	private ColorEditor _colorEditor;
  	private ChangeListenerCollection _changeListeners;
  
  	PaletteWidget(Palette palette, ColorEditor colorEditor) {
  		super();
  		_colorEditor = colorEditor;
  		Element div = DOM.createDiv();
  		setElement(div);
  		sinkEvents(Event.ONMOUSEDOWN | Event.ONDBLCLICK);
  		_subdivs = new ArrayList<Element>();
  		_divWidth = 12;
  		_divHeight = 12;
  		_margin = 5;
  		_columnCount = 10;
  		_selectedColorIndex = -1;
  		setPalette(palette);
  	}
  	
  	public Palette getPalette() {
  		return _palette;
  	}
  	
  	public void paletteHasChanged(Palette palette) {
  		refresh();
  	}
  	
  	public void setPalette(Palette palette) {
  		if (_palette != null) {
  			_palette.removePaletteListener(this);
  		}
  		_palette = palette;
  		if (_palette != null) {
  			_palette.addPaletteListener(this);
  		}
  		refresh();
  		if (_selectedColorIndex == -1) {
  			selectColor(0);
  		}
  	}
  	
  	private void refresh() {
  
  		Element div = getElement();
  		
  		// Adjust the number of subdivs so that it matches the number
  		// of colors in the palette.
  		int subdivCount = _subdivs.size();
  		int colorCount = (_palette == null) ? 0 : _palette.getSize();
  		
  		if (subdivCount > colorCount) {
  			for (int i = subdivCount - 1; i >= colorCount; i--) {
  				Element subdiv = _subdivs.get(i);
  				DOM.removeChild(div, subdiv);
 				_subdivs.remove(i);
 			}
 		} else if (subdivCount < colorCount) {
 			for (int i = subdivCount; i < colorCount; i++) {
 				int row = i / _columnCount;
 				int col = i % _columnCount;
 				int x = _margin + (col * (_divWidth + _margin));
 				int y = _margin + (row * (_divHeight + _margin));
 				Element subdiv = DOM.createDiv();
 				DOM.setStyleAttribute(subdiv, "position", "absolute");
 				DOM.setStyleAttribute(subdiv, "width", _divWidth + "px");
 				DOM.setStyleAttribute(subdiv, "height", _divHeight + "px");
 				DOM.setStyleAttribute(subdiv, "left", x + "px");
 				DOM.setStyleAttribute(subdiv, "top",  y + "px");
 				DOM.setElementAttribute(subdiv, "class", "palette");
 				DOM.appendChild(div, subdiv);
 				_subdivs.add(subdiv);
 			}			
 		}
 
 		// Set the subdiv color according to the palette
 		for (int i = 0; i < colorCount; i++) {
 			Color color = _palette.getColor(i);
 			Element subdiv = _subdivs.get(i);
 			DOM.setStyleAttribute(subdiv, "backgroundColor", color.toString());
 		}
 		DOM.setStyleAttribute(div, "position", "relative");
 		DOM.setStyleAttribute(div, "width", _margin + _columnCount * (_divWidth + _margin) + "px");
 		DOM.setStyleAttribute(div, "height", _margin + ((colorCount / _columnCount) + ((colorCount % _columnCount != 0) ? 1 : 0)) * (_divHeight + _margin) + "px");
 	}
 
 	@Override
 	public void onBrowserEvent(Event event) {
 		Element div = getElement();
 		super.onBrowserEvent(event);
 		switch (DOM.eventGetType(event)) {
 			case Event.ONMOUSEDOWN:
 				int x = DOM.eventGetClientX(event) - getAbsoluteLeft(div);
 				int col = x / (_divWidth + _margin);
 				int y = DOM.eventGetClientY(event) - getAbsoluteTop(div);
 				int row = y / (_divHeight + _margin);
 				if (col < _columnCount) {
 					int index = _selectedColorIndex;
 					selectColor(row * _columnCount + col);
 					if ((index != _selectedColorIndex) && (_changeListeners != null)) {
 						_changeListeners.fireChange(this);
 					}
 				}
 				break;
 			case Event.ONDBLCLICK:
 				if (_palette != null && _selectedColorIndex != -1 && _colorEditor != null) {
 					_colorEditor.setColor(_palette.getColor(_selectedColorIndex), this);
 					_colorEditor.show();
 				}
 				break;
 		}
 	}
 	
 	public void selectColor(int index) {
 		if (index != _selectedColorIndex) {
 			if ((0 <= index) && (index < _subdivs.size())) {
 				// Reset border of previously selected color
 				if ((0 <= _selectedColorIndex) && (_selectedColorIndex < _subdivs.size())) {
 					Element subdiv = _subdivs.get(_selectedColorIndex);
 					DOM.setElementAttribute(subdiv, "class", "palette");
 				}
 				// Set border of newly selected color
 				Element subdiv = _subdivs.get(index);
 				DOM.setElementAttribute(subdiv, "class", "palette-selected");
 				_selectedColorIndex = index;
 			}
 		}
 	}
 	
 	public int getSelectedColorIndex() {
 		return _selectedColorIndex;
 	}
 	
 	public Color getSelectedColor() {
 		return (_selectedColorIndex == -1) ? null : _palette.getColor(_selectedColorIndex);
 	}
 	
 	
 	public static native int getAbsoluteTop(Element elem) /*-{
 	    var top = 0;
 	    var curr = elem;
 	    // This intentionally excludes body which has a null offsetParent.    
 	    while (curr) {
 	      top -= curr.scrollTop;
 	      curr = curr.offsetParent;
 	    }
 	    while (elem) {
 	      top += elem.offsetTop;
 	      elem = elem.offsetParent;
 	    }
 	    return top;
 	}-*/;
   
 	public static native int getAbsoluteLeft(Element elem) /*-{
 	    var left = 0;
 	    var curr = elem;
 	    // This intentionally excludes body which has a null offsetParent.    
 	    while (curr) {
 	      left -= curr.scrollLeft;
 	      curr = curr.offsetParent;
 	    }
 	    while (elem) {
 	      left += elem.offsetLeft;
 	      elem = elem.offsetParent;
 	    }
 	    return left;
 	}-*/;
 
 	public void onChange(Widget sender) {
 		_colorEditor.getColor(_palette.getColor(_selectedColorIndex));
 		_palette.setColor(_selectedColorIndex, _palette.getColor(_selectedColorIndex));
 	}
 
 	public void addChangeListener(ChangeListener listener) {
 		if (_changeListeners == null) {
 			_changeListeners = new ChangeListenerCollection();
 		}
 		_changeListeners.add(listener);
 	}
 
 	public void removeChangeListener(ChangeListener listener) {
 		if (_changeListeners != null) {
 			_changeListeners.remove(listener);
 		}
 	}
 }