/**
 * Copyright (c) 2011, 2014 - Lunifera GmbH (Gross Enzersdorf)
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: 
 * 		Florian Pirchner - Initial implementation
 */

 package org.eclipse.osbp.vaaclipse.addons.app.webapp;

import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.inject.Inject;

import org.eclipse.e4.core.services.events.IEventBroker;
import org.eclipse.e4.ui.workbench.UIEvents;
import org.eclipse.e4.ui.workbench.UIEvents.EventTags;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventHandler;

import com.vaadin.ui.Component;

/**
 * The Class WidgetModelAssociations.
 */
public class WidgetModelAssociations implements IWidgetModelAssociations,
		EventHandler {

	/** The event broker. */
	@Inject
	private IEventBroker eventBroker;

	/** The cache. */
	private Map<Object, EObject> cache = Collections
			.synchronizedMap(new HashMap<Object, EObject>());

	// third party assocations may provide widget to model element mappings for
	/** The third party assocations. */
	// different UI models, like ECView
	private Set<IWidgetModelAssociations> thirdPartyAssocations = new HashSet<IWidgetModelAssociations>();

	/**
	 * Setup.
	 */
	@PostConstruct
	void setup() {
		eventBroker.subscribe(UIEvents.UIElement.TOPIC_WIDGET, this);
	}

	/* (non-Javadoc)
	 * @see org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations#getElement(java.lang.Object)
	 */
	@Override
	public EObject getElement(Object component) {
		if (component == null) {
			return null;
		}

		// first, try to find the Vaaclipse component in the current cache
		EObject result = cache.get(component);

		// if no widget could be found here, lets try the thirdparty
		// associations like ECView
		if (result == null) {
			for (IWidgetModelAssociations thirdParty : thirdPartyAssocations) {
				result = thirdParty.getElement(component);
				if (result != null) {
					break;
				}
			}
		}

		// at last iterate all parent elements to find the next component in the
		// Vaaclipse ui element hierarchy
		if (result == null) {
			if (component instanceof Component) {
				result = getElementByParent(((Component) component).getParent());
			}
		}

		return result;
	}

	/**
	 * Gets the element by parent.
	 *
	 * @param component
	 *            the component
	 * @return the element by parent
	 */
	public EObject getElementByParent(Object component) {
		if (component == null) {
			return null;
		}

		EObject result = cache.get(component);
		if (result == null) {
			if (component instanceof Component) {
				result = getElementByParent(((Component) component).getParent());
			}
		}

		return result;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations#getWidget(org.eclipse.emf.ecore.EObject)
	 */
	@Override
	public Object getWidget(EObject element) {
		if (cache.values().contains(element)) {
			for (Map.Entry<Object, EObject> entry : cache.entrySet()) {
				if (entry.getValue() == element) {
					return entry.getKey();
				}
			}
		}

		// if no widget could be found here, lets try the thirdparty
		// associations
		for (IWidgetModelAssociations thirdParty : thirdPartyAssocations) {
			Object widget = thirdParty.getWidget(element);
			if (widget != null) {
				return widget;
			}
		}

		return null;
	}

	/* (non-Javadoc)
	 * @see org.osgi.service.event.EventHandler#handleEvent(org.osgi.service.event.Event)
	 */
	@Override
	public void handleEvent(Event event) {
		if (UIEvents.EventTypes.SET.equals(event.getProperty(EventTags.TYPE))) {
			EObject changedObj = (EObject) event.getProperty(EventTags.ELEMENT);
			Object widget = event.getProperty(EventTags.WIDGET);
			if (widget == null) {
				cache.remove(changedObj);
			} else {
				cache.put(widget, changedObj);
			}
		}
	}

	/* (non-Javadoc)
	 * @see org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations#addThirdParty(org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations)
	 */
	public boolean addThirdParty(IWidgetModelAssociations e) {
		return thirdPartyAssocations.add(e);
	}

	/* (non-Javadoc)
	 * @see org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations#removeThirdParty(org.eclipse.osbp.vaaclipse.publicapi.events.IWidgetModelAssociations)
	 */
	public boolean removeThirdParty(IWidgetModelAssociations o) {
		return thirdPartyAssocations.remove(o);
	}

	/**
	 * Destroy.
	 */
	@PreDestroy
	void destroy() {
		eventBroker.unsubscribe(this);
	}

}