ResourceUtility.java

/*
 * RHQ Management Platform
 * Copyright (C) 2005-2013 Red Hat, Inc.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

package org.rhq.core.domain.util;

import static org.rhq.core.domain.resource.ResourceCategory.PLATFORM;

import java.util.LinkedHashSet;
import java.util.Set;

import org.jetbrains.annotations.NotNull;

import org.rhq.core.domain.resource.Resource;
import org.rhq.core.domain.resource.ResourceCategory;
import org.rhq.core.domain.resource.ResourceType;

/**
 * A set of utility methods for working with {@link Resource}s.
 *
 * @since 4.4
 * @author Ian Springer
 */
public class ResourceUtility {

    public static Resource getChildResource(Resource parent, ResourceType type, String key) {
        for (Resource resource : parent.getChildResources()) {
            if (resource.getResourceType().equals(type) && resource.getResourceKey().equals(key)) {
                return resource;
            }
        }
        return null;
    }

    /**
     * Returns the set of child Resources defined by the given parent Resource, which are accepted by the specified
     * filter. If the filter is null, all of the parent Resource's children will be returned.
     *
     * @param parentResource the parent Resource
     * @param filter the filter; may be null
     *
     * @return the set of MeasurementDefinition defined by the given Resource type, which are accepted by the specified
     *         filter, or, if the filter is null, all of the type's MeasurementDefinitions
     */
    @NotNull
    public static Set<Resource> getChildResources(Resource parentResource,
                                                  ResourceFilter filter) {
        if (filter == null) {
            return parentResource.getChildResources();
        }
        Set<Resource> acceptedChildResources = new LinkedHashSet<Resource>();
        for (Resource childResource : parentResource.getChildResources()) {
            if (filter.accept(childResource)) {
                acceptedChildResources.add(childResource);
            }
        }
        return acceptedChildResources;
    }

    /**
     * Returns the base server or service of the specified <code>resource</code>.
     *
     * @param resource
     * @return the base server or service of the specified <code>resource</code>.
     * @throws IllegalArgumentException if <code>resource</code> is null
     */
    public static Resource getBaseServerOrService(Resource resource) {
        if (resource == null) {
            throw new IllegalArgumentException("resource is null");
        }
        Resource current, parent = resource;
        do {
            current = parent;
            parent = current.getParentResource();
        } while (parent != null && parent.getResourceType().getCategory() != PLATFORM);
        return current;
    }

    /**
     * Returns first ancestor whose type is parentType.
     *
     * @param resource
     * @param parentType Type of the ancestor needed.
     * @return The ancestor of resource whose type is parentType.
     * @throws IllegalArgumentException if <code>resource</code> or <code>parentType</code> is null
     */
    public static Resource getAncestorResourceOfType(Resource resource, String parentType) {
        if (resource == null) {
            throw new IllegalArgumentException("resource is null");
        }
        if (parentType == null) {
            throw new IllegalArgumentException("parentType is null");
        }
        while (true) {
            if (resource.getResourceType().getName().equals(parentType)) {
                return resource;
            }
            resource = resource.getParentResource();
            if (resource == null) {
                return null;
            }
        }
    }

    /**
     * Returns true if <code>possibleAncestor</code> is an ancestor of <code>resource</code> or itself.
     * false in other case.
     *
     * @param resource
     * @param possibleAncestor possible ancestor of <code>resource</code>.
     * @return true if <code>possibleAncestor</code> is an ancestor of <code>resource</code> or itself, false in other case.
     */
    public static boolean isAncestor(Resource resource, Resource possibleAncestor) {
        if (resource == null) {
            throw new IllegalArgumentException("resource is null");
        }
        if (possibleAncestor == null) {
            throw new IllegalArgumentException("possibleAncestor is null");
        }
        while(true) {
            if (resource.equals(possibleAncestor)) {
                return true;
            }
            resource = resource.getParentResource();
            if (resource == null) {
                return false;
            }
        }
    }

    private ResourceUtility() {
        // Defensive
    }

}