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/*
 * Copyright (c) OSGi Alliance (2009). All Rights Reserved.
 * 
 * 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.osgi.jmx;

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

import javax.management.openmbean.ArrayType;
import javax.management.openmbean.CompositeType;
import javax.management.openmbean.OpenDataException;
import javax.management.openmbean.OpenType;
import javax.management.openmbean.TabularType;

/**
 * The item class enables the definition of open types in the appropriate
 * interfaces.
 * 
 * This class contains a number of methods that make it possible to create open
 * types for {@link CompositeType}, {@link TabularType}, and {@link ArrayType}.
 * The normal creation throws a checked exception, making it impossible to use
 * them in a static initializer. The constructors are also not very suitable
 * for static construction.
 * 
 * 
 * An Item instance describes an item in a Composite Type. It groups the triplet
 * of name, description, and Open Type. These Item instances allows the
 * definitions of an item to stay together.
 * 
 * @version $Revision: 8482 $
 * @Immutable
 * 
 * ALED/BROOKLYN: This is a verbatim copy of from org.osgi.jmx.JmxConstants, to avoid  
 * pulling in the dependency org.osgi.enterprise-4.2.0, and its chain of dependencies.
 * The only difference is this comment.
 */
public class Item {

    /**
     * The name of this item.
     */
    private final String name;

    /**
     * The description of this item.
     */
    private final String description;

    /**
     * The type of this item.
     */
    private final OpenType type;

    /**
     * Create a triple of name, description, and type. This triplet is used in
     * the creation of a Composite Type.
     * 
     * @param name
     *            The name of the item.
     * @param description
     *            The description of the item.
     * @param type
     *            The Open Type of this item.
     * @param restrictions
     *            Ignored, contains list of restrictions
     */
    public Item(String name, String description, OpenType type,
            String... restrictions) {
        this.name = name;
        this.description = description;
        this.type = type;
    }

    /**
     * Create a Tabular Type.
     * 
     * @param name
     *            The name of the Tabular Type.
     * @param description
     *            The description of the Tabular Type.
     * @param rowType
     *            The Open Type for a row
     * @param index
     *            The names of the items that form the index .
     * @return A new Tabular Type composed from the parameters.
     * @throws RuntimeException
     *             when the Tabular Type throws an OpenDataException
     */
    static public TabularType tabularType(String name, String description,
            CompositeType rowType, String... index) {
        try {
            return new TabularType(name, description, rowType, index);
        } catch (OpenDataException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Create a Composite Type
     * 
     * @param name
     *            The name of the Tabular Type.
     * @param description
     *            The description of the Tabular Type.
     * @param items
     *            The items that describe the composite type.
     * @return a new Composite Type
     * @throws RuntimeException
     *             when the Tabular Type throws an OpenDataException
     */
    static public CompositeType compositeType(String name, String description,
            Item... items) {
        return extend(null, name, description, items);
    }

    /**
     * Return a new Array Type.
     * 
     * @param dim
     *            The dimension
     * @param elementType
     *            The element type
     * @return A new Array Type
     */
    public static ArrayType arrayType(int dim, OpenType elementType) {
        try {
            return new ArrayType(dim, elementType);
        } catch (OpenDataException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Extend a Composite Type by adding new items. Items can override items in
     * the parent type.
     * 
     * @param parent
     *            The parent type, can be {@code null}
     * @param name
     *            The name of the type
     * @param description
     *            The description of the type
     * @param items
     *            The items that should be added/override to the parent type
     * @return A new Composite Type that extends the parent type
     * @throws RuntimeException
     *             when an OpenDataException is thrown
     */
    public static CompositeType extend(CompositeType parent, String name,
            String description, Item... items) {
        Set all = new LinkedHashSet();

        if (parent != null) {
            for (Object nm : parent.keySet()) {
                String key = (String) nm;
                all.add(new Item(key, parent.getDescription(key),
                        parent.getType(key)));
            }
        }

        Collections.addAll(all, items);

        int size = all.size();
        String names[] = new String[size];
        String descriptions[] = new String[size];
        OpenType types[] = new OpenType[size];

        int m = 0;
        for (Item item : all) {
            names[m] = item.name;
            descriptions[m] = item.description;
            types[m] = item.type;
            m++;
        }

        try {
            return new CompositeType(name, description, names, descriptions,
                    types);
        } catch (OpenDataException e) {
            throw new RuntimeException(e);
        }
    }

}