guacamole-ext/src/main/java/org/apache/guacamole/net/auth/Directory.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.guacamole.net.auth;

import java.util.Collection;
import java.util.Set;
import org.apache.guacamole.GuacamoleException;

/**
 * Provides access to a collection of all objects with associated identifiers,
 * and allows user manipulation and removal. Objects returned by a Directory
 * are not necessarily backed by the stored objects, thus updating an object
 * always requires calling the update() function.
 *
 * @param <ObjectType>
 *     The type of objects stored within this Directory.
 */
public interface Directory<ObjectType extends Identifiable> {

    /**
     * All Directory types that may be found on the {@link UserContext}
     * interface.
     */
    public enum Type {

        /**
         * The type of a Directory that contains {@link ActiveConnection}
         * objects.
         */
        ACTIVE_CONNECTION(ActiveConnection.class),

        /**
         * The type of a Directory that contains {@link Connection}
         * objects.
         */
        CONNECTION(Connection.class),

        /**
         * The type of a Directory that contains {@link ConnectionGroup}
         * objects.
         */
        CONNECTION_GROUP(ConnectionGroup.class),

        /**
         * The type of a Directory that contains {@link SharingProfile}
         * objects.
         */
        SHARING_PROFILE(SharingProfile.class),

        /**
         * The type of a Directory that contains {@link User} objects.
         */
        USER(User.class),

        /**
         * The type of a Directory that contains {@link UserGroup}
         * objects.
         */
        USER_GROUP(UserGroup.class);

        /**
         * The base class of the type of object stored within the type of
         * Directory represented by this Directory.Type.
         */
        private final Class<? extends Identifiable> objectType;

        /**
         * Creates a new Directory.Type representing the type of a Directory
         * that contains only subclasses of the given class.
         *
         * @param objectType
         *     The base class of the type of object stored within the type of
         *     Directory represented by this Directory.Type.
         */
        private Type(Class<? extends Identifiable> objectType) {
            this.objectType = objectType;
        }

        /**
         * Returns the base class of the type of object stored within a
         * {@link Directory} of this type.
         *
         * @return
         *     The base class of the type of object stored within a
         *     {@link Directory} of this type.
         */
        public Class<? extends Identifiable> getObjectType() {
            return objectType;
        }

        /**
         * Returns the Directory.Type representing the type of a Directory that
         * could contain an object having the given class. The class may be a
         * subclass of the overall base class of the objects stored within the
         * Directory.
         *
         * @param objectType
         *     The class to determine the Directory.Type of.
         *
         * @return
         *     The Directory.Type representing the type of a Directory that
         *     could contain an object having the given class, or null if there
         *     is no such Directory available via the UserContext interface.
         */
        public static Type of(Class<? extends Identifiable> objectType) {

            for (Type type : Type.values()) {
                if (type.getObjectType().isAssignableFrom(objectType))
                    return type;
            }

            return null;

        }

    }

    /**
     * Returns the object having the given identifier. Note that changes to
     * the object returned will not necessarily affect the object stored within
     * the Directory. To update an object stored within an
     * Directory such that future calls to get() will return the updated
     * object, you must call update() on the object after modification.
     *
     * @param identifier The identifier to use when locating the object to
     *                   return.
     * @return The object having the given identifier, or null if no such object
     *         exists.
     *
     * @throws GuacamoleException If an error occurs while retrieving the
     *                            object, or if permission for retrieving the
     *                            object is denied.
     */
    ObjectType get(String identifier) throws GuacamoleException;

    /**
     * Returns the objects having the given identifiers. Note that changes to
     * any object returned will not necessarily affect the object stored within
     * the Directory. To update an object stored within a
     * Directory such that future calls to get() will return the updated
     * object, you must call update() on the object after modification.
     *
     * @param identifiers
     *     The identifiers to use when locating the objects to return.
     *
     * @return
     *     The objects having the given identifiers. If any identifiers do not
     *     correspond to accessible objects, those identifiers will be ignored.
     *     If no objects correspond to any of the given identifiers, the
     *     returned collection will be empty.
     *
     * @throws GuacamoleException
     *     If an error occurs while retrieving the objects, or if permission
     *     to retrieve the requested objects is denied.
     */
    Collection<ObjectType> getAll(Collection<String> identifiers)
            throws GuacamoleException;

    /**
     * Returns a Set containing all identifiers for all objects within this
     * Directory.
     *
     * @return A Set of all identifiers.
     * @throws GuacamoleException If an error occurs while retrieving
     *                            the identifiers.
     */
    Set<String> getIdentifiers() throws GuacamoleException;

    /**
     * Adds the given object to the overall set. If a new identifier is
     * created for the added object, that identifier will be automatically
     * assigned via setIdentifier().
     *
     * @param object
     *     The object to add.
     *
     * @throws GuacamoleException
     *     If an error occurs while adding the object, or if adding the object
     *     is not allowed.
     */
    void add(ObjectType object)
            throws GuacamoleException;

    /**
     * Updates the stored object with the data contained in the given object.
     *
     * @param object The object which will supply the data for the update.
     *
     * @throws GuacamoleException If an error occurs while updating the object,
     *                            or if updating the object is not allowed.
     */
    void update(ObjectType object)
            throws GuacamoleException;

    /**
     * Removes the object with the given identifier from the overall set.
     *
     * @param identifier The identifier of the object to remove.
     *
     * @throws GuacamoleException If an error occurs while removing the object,
     *                            or if removing the object is not allowed.
     */
    void remove(String identifier) throws GuacamoleException;

    /**
     * Attempt to perform the provided operation atomically if possible. If the
     * operation can be performed atomically, the atomic flag will be set to
     * true, and the directory passed to the provided operation callback will
     * peform directory operations atomically within the operation callback.
     *
     * @param operation
     *     The directory operation that should be performed atomically.
     *
     * @throws GuacamoleException
     *     If an error occurs during execution of the provided operation.
     */
    default void tryAtomically(AtomicDirectoryOperation<ObjectType> operation)
            throws GuacamoleException {

        // By default, perform the operation non-atomically. If atomic operation
        // is supported by an implementation, it must be implemented there.
        operation.executeOperation(false, this);

    }

}