/**
 * 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.storm.security.auth;

import java.security.Principal;
import java.util.Map;

/**
 * Storm can be configured to launch worker processed as a given user. Some transports need to map the Principal to a local user name.
 */
public interface IPrincipalToLocal {
    /**
     * Invoked once immediately after construction.
     *
     * @param topoConf Storm configuration
     */
    void prepare(Map<String, Object> topoConf);

    /**
     * Convert a Principal to a local user name.
     *
     * @param principal the principal to convert
     * @return The local user name.
     */
    default String toLocal(Principal principal) {
        return principal == null ? null : toLocal(principal.getName());
    }

    String toLocal(String principalName);
}