org.eclipse.osbp.ecview.extension.presentation.vaadin/src/org/eclipse/osbp/ecview/extension/presentation/vaadin/components/common/ECViewComponent.java

/**
 *                                                                            
 *  Copyright (c) 2011, 2016 - Loetz GmbH&Co.KG (69115 Heidelberg, Germany) 
 *                                                                            
 *  All rights reserved. This program and the accompanying materials           
 *  are made available under the terms of the Eclipse Public License 2.0        
 *  which accompanies this distribution, and is available at                  
 *  https://www.eclipse.org/legal/epl-2.0/                                 
 *                                 
 *  SPDX-License-Identifier: EPL-2.0                                 
 *                                                                            
 *  Contributors:                                                      
 * 	   Florian Pirchner - Initial implementation
 * 
 */
package org.eclipse.osbp.ecview.extension.presentation.vaadin.components.common;

import java.util.HashMap;
import java.util.Map;

import org.eclipse.osbp.ecview.core.common.context.ContextException;
import org.eclipse.osbp.ecview.core.common.context.IViewContext;
import org.eclipse.osbp.ecview.core.common.extender.IECViewProviderService;
import org.eclipse.osbp.ecview.core.common.model.core.YView;
import org.eclipse.osbp.runtime.web.ecview.presentation.vaadin.VaadinRenderer;
import org.osgi.framework.BundleContext;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.ServiceReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.vaadin.ui.CustomComponent;
import com.vaadin.ui.Notification;
import com.vaadin.ui.Notification.Type;
import com.vaadin.ui.VerticalLayout;

/**
 * This component shows an rendered ECView component for the given DTO instance.
 * <p>
 * Attention: This component needs to be {@link #dispose() disposed} if not used
 * anymore.
 */
@SuppressWarnings("serial")
public class ECViewComponent extends CustomComponent {

	/** The Constant LOGGER. */
	private static final Logger LOGGER = LoggerFactory
			.getLogger(ECViewComponent.class);

	/** The cache. */
	private Map<String, IViewContext> cache = new HashMap<>();

	/** The layout. */
	private VerticalLayout layout;
	
	/** The current view context. */
	private IViewContext currentViewContext;

	/** The callback. */
	private ViewProviderCallback callback;

	/**
	 * Instantiates a new EC view component.
	 */
	public ECViewComponent() {
		this(null);
	}

	/**
	 * Instantiates a new EC view component.
	 *
	 * @param callback
	 *            the callback
	 */
	public ECViewComponent(ViewProviderCallback callback) {
		this.callback = callback;

		setSizeFull();

		layout = new VerticalLayout();
		layout.setSizeFull();
		setCompositionRoot(layout);

	}

	/**
	 * Will render and show a bound view instance for the given dto.
	 * 
	 * @param viewId
	 *            the id of the view
	 * @param dto
	 *            the dto instance to be displayed
	 * @param properties
	 *            render properties
	 * @return the rendered view context or <code>null</code>.
	 */
	public IViewContext setValue(String viewId, Object dto,
			Map<String, Object> properties) {
		// if the type of dto did not change, we only need to set the new dto
		// instance
		String currentId = null;
		if (currentViewContext != null) {
			currentId = currentViewContext.getViewEditpart().getName();
		}

		if (viewId.equals(currentId)) {
			currentViewContext.setBean(getBeanSlotName(properties), dto);
		} else {
			// remove all components
			layout.removeAllComponents();

			// determine the resulting ui content
			IViewContext context = cache.get(viewId);
			if (context == null) {
				context = createNewContext(viewId, properties);
			}

			if (context != null) {
				if (!context.isRendered()) {
					try {
						new VaadinRenderer()
								.render(context, layout, properties);
					} catch (ContextException e) {
						LOGGER.error("{}", e);
						Notification.show(
								viewId + " caused " + e.getLocalizedMessage()
										+ "!", Type.ERROR_MESSAGE);
					}
				}

				// set data to the view
				if (dto != null) {
					context.setBean(getBeanSlotName(properties), dto);
				}
			}
			currentViewContext = context;
		}
		return currentViewContext;
	}

	/**
	 * Gets the bean slot name.
	 *
	 * @param properties
	 *            the properties
	 * @return the bean slot name
	 */
	protected String getBeanSlotName(Map<String, Object> properties) {
		return (String) properties.get(IViewContext.PROP_SLOT);
	}

	/**
	 * Creates a new context for the given dto using the properties.
	 *
	 * @param viewId
	 *            the view id
	 * @param properties
	 *            the properties
	 * @return the i view context
	 */
	protected IViewContext createNewContext(String viewId,
			Map<String, Object> properties) {

		IViewContext context = null;
		BundleContext bc = FrameworkUtil.getBundle(getClass())
				.getBundleContext();
		ServiceReference<IECViewProviderService> ref = bc
				.getServiceReference(IECViewProviderService.class);
		if (ref != null) {
			IECViewProviderService service = bc.getService(ref);

			YView yView = null;
			// check whether the owner wants to contribute a view model
			if (callback != null) {
				yView = callback.getView(viewId, properties);
			}

			if (yView != null) {
				// create a context for the provided view model
				context = service.getViewContext(yView);
			} else {
				// else check the service for a proper view model
				context = service.getViewContext(viewId);
			}
			if (context != null) {
				cache.put(viewId, context);
			}

			bc.ungetService(ref);
		} else {
			LOGGER.error("No view available for " + viewId);
		}

		return context;
	}

	/**
	 * Disposes the component.
	 */
	public void dispose() {
		cache.values().forEach(it -> {
			try {
				it.dispose();
			} catch (Exception e) {
				LOGGER.error("{}", e);
			}
		});
		cache.clear();
		cache = null;

		layout = null;
		currentViewContext = null;
	}

	/**
	 * A callback class to allow owners of this class to create context specifix
	 * views.
	 */
	public interface ViewProviderCallback {

		/**
		 * Returns a custom view for the given id and properties. Or
		 * <code>null</code> if a default view should be used.
		 *
		 * @param viewId
		 *            the view id
		 * @param properties
		 *            the properties
		 * @return the view
		 */
		YView getView(String viewId, Map<String, Object> properties);
	}
}