/**
 * 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.zookeeper.server.admin;

import java.util.Map;
import java.util.Set;

import org.apache.zookeeper.server.ZooKeeperServer;

/**
 * Interface implemented by all commands runnable by JettyAdminServer.
 *
 * @see CommandBase
 * @see Commands
 * @see JettyAdminServer
 */
public interface Command {
    /**
     * The set of all names that can be used to refer to this command (e.g.,
     * "configuration", "config", and "conf").
     */
    Set<String> getNames();

    /**
     * The name that is returned with the command response and that appears in
     * the list of all commands. This should be a member of the set returned by
     * getNames().
     */
    String getPrimaryName();

    /**
     * A string documentating this command (e.g., what it does, any arguments it
     * takes).
     */
    String getDoc();

    /**
     * Run this command. Commands take a ZooKeeperServer and String-valued
     * keyword arguments and return a map containing any information
     * constituting the response to the command. Commands are responsible for
     * parsing keyword arguments and performing any error handling if necessary.
     * Errors should be reported by setting the "error" entry of the returned
     * map with an appropriate message rather than throwing an exception.
     *
     * @param zkServer
     * @param kwargs keyword -> argument value mapping
     * @return Map representing response to command containing at minimum:
     *    - "command" key containing the command's primary name
     *    - "error" key containing a String error message or null if no error
     */
    CommandResponse run(ZooKeeperServer zkServer, Map<String, String> kwargs);
}