/**
 * Copyright (c) 2007-2014 Kaazing Corporation. All rights reserved.
 * 
 * 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.kaazing.net.auth;


import java.util.Collection;

/**
 * A NegotiableChallengeHandler can be used to directly respond to
 * "Negotiate" challenges, and in addition, can be used indirectly in conjunction
 * with a {@link NegotiateChallengeHandler}
 * to assist in the construction of a challenge response using object identifiers.
 *
 * @see <a href="http://tools.ietf.org/html/rfc4178#section-4.2.1">RFC 4178 Section 4.2.1</a> for details
 *      about how the supported object identifiers contribute towards the initial context token in the challenge response.
 *
 * <p/>
 *
 */
public abstract class NegotiableChallengeHandler extends ChallengeHandler {

    /**
     * Creates a new instance of {@link NegotiableChallengeHandler} using the
     * {@link ServiceLoader} API with the implementation specified under
     * META-INF/services.
     * 
     * @return NegotiableChallengeHandler
     */
    public static NegotiableChallengeHandler create() {
        return create(NegotiableChallengeHandler.class);
    }

    /**
     * Creates a new instance of {@link NegotiableChallengeHandler} with the
     * specified {@link ClassLoader} using the {@link ServiceLoader} API with
     * the implementation specified under META-INF/services.
     * 
     * @param  classLoader          ClassLoader to be used to instantiate
     * @return NegotiableChallengeHandler
     */
    public static NegotiableChallengeHandler create(ClassLoader classLoader) {
        return create(NegotiableChallengeHandler.class, classLoader);
    }

    /**
     * Default constructor.
     */
    protected NegotiableChallengeHandler() {
    }

    /**
     * Return a collection of string representations of object identifiers
     * supported by this challenge handler implementation, in dot-separated notation.
     * For example, {@literal 1.3.5.1.5.2}.
     *
     * @return a collection of string representations of object identifiers
     *         supported by this challenge handler implementation.
     */
    public abstract Collection<String> getSupportedOids();

    /**
     * Provide a general login handler to be used in association with this challenge handler.
     * The login handler is used to assist in obtaining credentials to respond to any
     * challenge requests when this challenge handler handles the request.
     *
     * @param loginHandler a login handler for credentials.
     *
     * @return this challenge handler object, to support chained calls
     */
    public abstract NegotiableChallengeHandler setLoginHandler(LoginHandler loginHandler);

    /**
     * Get the general login handler associated with this challenge handler.
     * A login handler is used to assist in obtaining credentials to respond to challenge requests.
     *
     * @return a login handler to assist in providing credentials, or {@code null} if none has been established yet.
     */
    public abstract LoginHandler getLoginHandler() ;
}