/*****************************************************************************
 * Copyright (c) 2010 CEA LIST.
 *
 *    
 * 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:
 * 
 * 		Yann Tanguy (CEA LIST) yann.tanguy@cea.fr - Initial API and implementation
 *
 *****************************************************************************/
package org.eclipse.papyrus.views.modelexplorer.handler;

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

import org.eclipse.core.commands.IHandler;
import org.eclipse.emf.common.command.Command;
import org.eclipse.emf.common.command.UnexecutableCommand;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.URIConverter;
import org.eclipse.emf.edit.domain.AdapterFactoryEditingDomain;
import org.eclipse.emf.edit.domain.EditingDomain;
import org.eclipse.gmf.runtime.common.core.command.CompositeCommand;
import org.eclipse.gmf.runtime.common.core.command.ICommand;
import org.eclipse.gmf.runtime.emf.type.core.requests.DestroyElementRequest;
import org.eclipse.papyrus.infra.services.edit.service.ElementEditServiceUtils;
import org.eclipse.papyrus.infra.services.edit.service.IElementEditService;

/**
 * Default handler for Delete command used in the ModelExplorer contextual menu.
 * 
 */
public class DeleteCommandHandler extends AbstractCommandHandler implements IHandler {

	/** Current deleteCommand for selection (updated in {@link DeleteCommandHandler#isEnabled()}) */
	private Command deleteCommand;

	/**
	 * <pre>
	 * 
	 * Build the delete command for a set of EObject selected in the ModelExplorer.
	 * The delete command is given by the {@link IElementEditService} of selected 
	 * elements.
	 * 
	 * @return the composite deletion command for current selection
	 * 
	 * @TODO : Manage possible Diagrams listed in the selection
	 * 
	 * </pre>
	 */
	private Command buildCommand() {

		ICommand gmfCommand = null;

		// Parameters store the Request parameters of the previous request
		// if multiple elements are selected for deletion.
		Map parameters = new HashMap();

		for(EObject selectedEObject : getSelectedElements()) {

			if(selectedEObject == null) {
				continue;
			}

			IElementEditService provider = ElementEditServiceUtils.getCommandProvider(selectedEObject);
			if(provider == null) {
				continue;
			}

			// Retrieve delete command from the Element Edit service
			DestroyElementRequest request = new DestroyElementRequest(selectedEObject, false);
			// Add parameters (contains the list of previously dependents to be deleted
			// by previous commands.
			request.getParameters().putAll(parameters);

			ICommand deleteCommand = provider.getEditCommand(request);

			// Add current EObject destroy command to the global command
			gmfCommand = CompositeCommand.compose(gmfCommand, deleteCommand);

			// Store the new parameters for next delete command.
			parameters.clear();
			parameters.putAll(request.getParameters());
		}

		if(gmfCommand == null) {
			return UnexecutableCommand.INSTANCE;
		}

		Command emfCommand = new org.eclipse.papyrus.commands.wrappers.GMFtoEMFCommandWrapper(gmfCommand.reduce());
		return emfCommand;
	}

	/**
	 * 
	 * @see org.eclipse.papyrus.views.modelexplorer.handler.AbstractCommandHandler#getCommand()
	 * 
	 * @return current command (only built here when the stored command is null)
	 */
	protected Command getCommand() {
		// Don't cache the command, as it is no more refreshed by isEnabled().
		return buildCommand();
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public boolean isEnabled() {
		//we need to test if selected element is not a meta-class

		List<EObject> selectedElements = getSelectedElements();
		for(EObject current : selectedElements) {
			//FIXME use the method isReadOnly provided by the class EMFHelper 
			//TODO after the refactoring (currently, there is circular dependencies)
			if(isReadOnly(current)) {
				return false;
			}
			//the root of the model can't be deleted!
			if(current.eContainer() == null) {
				return false;
			}
		}

		if(selectedElements.size()==0){
			return false;
		}
		// Don't compute the delete command to know if it is enabled,
		// it can be WAY too slow...
		return true;
	}

	/**
	 * Tests if an EObject is read only
	 * Delegates to the EObject's editing domain if it can be found
	 * 
	 * @param eObject
	 * @return
	 *         True if the EObject is read only
	 */
	public static boolean isReadOnly(EObject eObject) {
		if(eObject != null) {
			EditingDomain domain = AdapterFactoryEditingDomain.getEditingDomainFor(eObject);
			return isReadOnly(eObject, domain);
		}
		return false;
	}

	/**
	 * Tests if an EObject is read only
	 * Delegates to the given editing domain if it isn't null
	 * 
	 * @param eObject
	 * @param domain
	 * @return
	 *         True if the EObject is read only
	 */
	public static boolean isReadOnly(EObject eObject, EditingDomain domain) {
		return isReadOnly(eObject.eResource(), domain);
	}

	/**
	 * Tests if the Resource is read only
	 * Delegates to the given editing domain if it isn't null
	 * 
	 * @param resource
	 * @param domain
	 * @return
	 *         True if the Resource is read only
	 */
	public static boolean isReadOnly(Resource resource, EditingDomain domain) {
		if(domain instanceof AdapterFactoryEditingDomain) {
			return ((AdapterFactoryEditingDomain)domain).isReadOnly(resource);
		}

		if(resource == null) {
			return false;
		}

		ResourceSet resourceSet = resource.getResourceSet();

		if(resourceSet == null) {
			return false;
		}

		Map<String, ?> attributes = resourceSet.getURIConverter().getAttributes(resource.getURI(), null);
		Boolean readOnly = (Boolean)attributes.get(URIConverter.ATTRIBUTE_READ_ONLY);

		return readOnly == null ? false : readOnly;
	}
}