/**********************************************
    * Copyright (C) 2011 Lukas Laag
    * This file is part of svgreal.
    * 
    * svgreal 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.
    * 
   * svgreal 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 svgreal.  If not, see http://www.gnu.org/licenses/
   **********************************************/
  package org.vectomatic.svg.edit.client.command;
  
  import java.util.Stack;
  
  import org.vectomatic.svg.edit.client.SvgrealApp;
  import org.vectomatic.svg.edit.client.event.CommandFactorySelectorChangeEvent;
  import org.vectomatic.svg.edit.client.event.CommandFactorySelectorChangeHandler;
  import org.vectomatic.svg.edit.client.event.HasCommandFactorySelectorChangeHandlers;
  import org.vectomatic.svg.edit.client.event.SelectionChangedProcessor;
  import org.vectomatic.svg.edit.client.event.SelectionChangedProxy;
  import org.vectomatic.svg.edit.client.model.svg.SVGElementModel;
  
  import com.extjs.gxt.ui.client.event.SelectionChangedEvent;
  import com.extjs.gxt.ui.client.event.SelectionService;
  import com.google.gwt.core.client.GWT;
  import com.google.gwt.event.shared.GwtEvent;
  import com.google.gwt.event.shared.HandlerRegistration;
  
  /**
   * Class to manage the command factories and their lifecycle.
   * @author laaglu
   */
  public class CommandFactorySelector implements HasCommandFactorySelectorChangeHandlers, SelectionChangedProcessor<SVGElementModel> {
  	private Stack<ICommandFactory> factoryStack;
  	private boolean suspended;
  	
  	public CommandFactorySelector() {
  		factoryStack = new Stack<ICommandFactory>();
  		SelectionService.get().addListener(new SelectionChangedProxy<SVGElementModel>(this));
  	}
  	
  	/**
  	 * Returns the currently active factory
  	 * @return
  	 */
  	public ICommandFactory getActiveFactory() {
  		if (suspended || factoryStack.empty()) {
  			return null;
  		}
  		return factoryStack.peek();
  	}
  	
  	/**
  	 * Pops the current factory from the stack.
  	 * @return
  	 */
  	public void popFactory() {
  		GWT.log("CommandFactorySelector.popFactory(" + getActiveFactory().getInstantiator().getName() + ")");
  		factoryStack.pop();
  		fireFactoryStackChangedEvent();
  	}
  	
  	/**
  	 * Pushes the factory on the stack.
  	 * @return
  	 */
  	public void pushFactory(ICommandFactory factory) {
  		GWT.log("CommandFactorySelector.pushFactory(" + factory.getInstantiator().getName() + ")");
  		factoryStack.push(factory);
  		fireFactoryStackChangedEvent();
  	}
  	
  	public int size() {
  		return factoryStack.size();
  	}
  	
  	public void fireFactoryStackChangedEvent() {
  		GWT.log("fireFactoryStackChangedEvent: " + toString());
  		fireEvent(new CommandFactorySelectorChangeEvent(getActiveFactory()));
  	}
  	
  	@Override
  	public void fireEvent(GwtEvent<?> event) {
  		SvgrealApp.getApp().getEventBus().fireEventFromSource(event, this);
  		
  	}
  	@Override
  	public HandlerRegistration addCommandFactoryChangeHandler(CommandFactorySelectorChangeHandler handler) {
  		return SvgrealApp.getApp().getEventBus().addHandlerToSource(CommandFactorySelectorChangeEvent.getType(), this, handler);
  	}
  
  	public void suspendAll() {
 		suspended = true;
 	}
 
 	public void resumeAll() {
 		suspended = false;
 	}
 	
 	public boolean isSuspended() {
 		return suspended;
 	}
 
 	@Override
 	public boolean processSelectionChanged(SelectionChangedEvent<SVGElementModel> se) {
 		GWT.log("CommandFactorySelector.processSelectionChanged(" + se.getSelection() + ")");
 		ICommandFactory factory = getActiveFactory();
 		if (factory instanceof SelectionChangedProcessor) {
 			((SelectionChangedProcessor)factory).processSelectionChanged(se);
 		}
 		return true;
 	}
 	
 	@Override
 	public String toString() {
 		StringBuilder builder = new StringBuilder("CommandFactorySelector(suspended=");
 		builder.append(suspended);
 		builder.append("");
 		builder.append(factoryStack);
 		builder.append(")");
 		return builder.toString();
 	}
 
 }