/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.views.navigator;

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

import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;

/**
 * Provides utilities for checking the validity of selections.
 * <p>
 * This class provides static methods only; it is not intended to be instantiated
 * or subclassed.
 * @since 2.0
 * </p>
 */
public class ResourceSelectionUtil {
    /* (non-Javadoc)
     * Private constructor to block instantiation.
     */
    private ResourceSelectionUtil() {
    }

    /**
     * Returns whether the types of the resources in the given selection are among 
     * the specified resource types.
     * 
     * @param selection the selection
     * @param resourceMask resource mask formed by bitwise OR of resource type
     *   constants (defined on <code>IResource</code>)
     * @return <code>true</code> if all selected elements are resources of the right
     *  type, and <code>false</code> if at least one element is either a resource
     *  of some other type or a non-resource
     * @see IResource#getType()
     */
    public static boolean allResourcesAreOfType(IStructuredSelection selection,
            int resourceMask) {
        Iterator resources = selection.iterator();
        while (resources.hasNext()) {
            Object next = resources.next();
            if (!(next instanceof IResource))
                return false;
            if (!resourceIsType((IResource) next, resourceMask))
                return false;
        }
        return true;
    }

    /**
     * Returns the selection adapted to IResource. Returns null
     * if any of the entries are not adaptable.
     * 
     * @param selection the selection
     * @param resourceMask resource mask formed by bitwise OR of resource type
     *   constants (defined on <code>IResource</code>)
     * @return IStructuredSelection or null if any of the entries are not adaptable.
     * @see IResource#getType()
     */
    public static IStructuredSelection allResources(
            IStructuredSelection selection, int resourceMask) {
        Iterator adaptables = selection.iterator();
        List result = new ArrayList();
        while (adaptables.hasNext()) {
            Object next = adaptables.next();
            if (next instanceof IAdaptable) {
                Object resource = ((IAdaptable) next)
                        .getAdapter(IResource.class);
                if (resource == null)
                    return null;
                else if (resourceIsType((IResource) resource, resourceMask))
                    result.add(resource);
            } else
                return null;
        }
        return new StructuredSelection(result);

    }

    /**
     * Returns whether the type of the given resource is among the specified 
     * resource types.
     * 
     * @param resource the resource
     * @param resourceMask resource mask formed by bitwise OR of resource type
     *   constants (defined on <code>IResource</code>)
     * @return <code>true</code> if the resources has a matching type, and 
     *   <code>false</code> otherwise
     * @see IResource#getType()
     */
    public static boolean resourceIsType(IResource resource, int resourceMask) {
        return (resource.getType() & resourceMask) != 0;
    }

}