org.spotter.eclipse.ui.handlers.DeleteHandler.java Source code

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Here is the source code for org.spotter.eclipse.ui.handlers.DeleteHandler.java

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/**
 * Copyright 2014 SAP AG
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.spotter.eclipse.ui.handlers;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.ui.commands.IElementUpdater;
import org.eclipse.ui.menus.UIElement;
import org.spotter.eclipse.ui.Activator;
import org.spotter.eclipse.ui.navigator.IDeletable;
import org.spotter.eclipse.ui.util.SpotterUtils;

/**
 * A delete handler for the delete command which deletes selected elements in
 * the DynamicSpotter Project Navigator.
 * 
 * @author Denis Knoepfle
 * 
 */
public class DeleteHandler extends AbstractHandler implements IElementUpdater {

    /**
     * The id of the corresponding delete command.
     */
    public static final String DELETE_COMMAND_ID = "org.spotter.eclipse.ui.commands.delete";

    /**
     * The default label used for the command in the popup menu
     */
    private static final String DEFAULT_LABEL = "Delete";

    @Override
    public Object execute(ExecutionEvent event) throws ExecutionException {
        Iterator<?> iter = getSelectionIterator();
        if (iter == null) {
            return null;
        }

        while (iter.hasNext()) {
            SpotterUtils.deleteNavigatorElement(iter.next());
        }

        return null;
    }

    /**
     * Only allow deletion if just elements are selected that are deletable.
     * 
     * @return <code>true</code> if only deletable elements are selected
     */
    @Override
    public boolean isEnabled() {
        return !getSelectedDeletables().isEmpty();
    }

    @SuppressWarnings("rawtypes")
    @Override
    public void updateElement(UIElement element, Map parameters) {
        List<IDeletable> deletables = getSelectedDeletables();

        String label = getLabelForDeletables(deletables);
        element.setText(label);
    }

    private String getLabelForDeletables(List<IDeletable> deletables) {
        IDeletable deletable = deletables.isEmpty() ? null : deletables.get(0);
        if (deletable == null) {
            return DEFAULT_LABEL;
        }

        String pluralLetter = deletables.size() > 1 ? "s" : "";
        String label = "Delete " + deletable.getElementTypeName() + pluralLetter;

        return label;
    }

    private List<IDeletable> getSelectedDeletables() {
        List<IDeletable> deletables = new ArrayList<>();

        Iterator<?> iter = getSelectionIterator();
        if (iter == null) {
            return deletables;
        }

        Class<?> firstDeletableClazz = null;

        while (iter.hasNext()) {
            Object selectedElement = iter.next();
            if (selectedElement instanceof IDeletable) {
                Class<?> clazz = selectedElement.getClass();
                if (firstDeletableClazz == null) {
                    firstDeletableClazz = clazz;
                    deletables.add((IDeletable) selectedElement);
                } else if (!firstDeletableClazz.equals(clazz)) {
                    // only allow same types in one delete
                    deletables.clear();
                    return deletables;
                } else {
                    // just add the element so it can be counted afterwards
                    deletables.add((IDeletable) selectedElement);
                }
            } else {
                // if any element not deletable return empty list
                deletables.clear();
                return deletables;
            }
        }
        return deletables;
    }

    private Iterator<?> getSelectionIterator() {
        Activator activator = Activator.getDefault();
        TreeViewer viewer = activator.getNavigatorViewer();
        if (viewer == null) {
            return null;
        }

        IStructuredSelection selection = (IStructuredSelection) viewer.getSelection();
        return selection.isEmpty() ? null : selection.iterator();
    }

}