/*
 * 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.samza.system;

import java.util.Map;
import java.util.Set;
import org.apache.samza.SamzaException;
import org.apache.samza.config.Config;
import org.apache.samza.config.SystemConfig;
import org.apache.samza.config.MapConfig;


/**
 * Provides a mapping from system name to a {@link SystemAdmin}. Needs to be started before use and stopped after use.
 */
public class SystemAdmins {
  private final Map<String, SystemAdmin> systemAdminMap;

  public SystemAdmins(Config config) {
    SystemConfig systemConfig = new SystemConfig(config);
    this.systemAdminMap = systemConfig.getSystemAdmins();
  }

  public SystemAdmins(Config config, String adminLabel) {
    SystemConfig systemConfig = new SystemConfig(config);
    this.systemAdminMap = systemConfig.getSystemAdmins(adminLabel);
  }

  /**
   * Creates a new instance of {@link SystemAdmins} with an empty admin mapping.
   * @return New empty instance of {@link SystemAdmins}
   */
  public static SystemAdmins empty() {
    return new SystemAdmins(new MapConfig());
  }

  public void start() {
    for (SystemAdmin systemAdmin : systemAdminMap.values()) {
      systemAdmin.start();
    }
  }

  public void stop() {
    for (SystemAdmin systemAdmin : systemAdminMap.values()) {
      systemAdmin.stop();
    }
  }

  public SystemAdmin getSystemAdmin(String systemName) {
    if (!systemAdminMap.containsKey(systemName)) {
      throw new SamzaException("Cannot get systemAdmin for system " + systemName);
    }
    return systemAdminMap.get(systemName);
  }

  public Set<String> getSystemNames() {
    return systemAdminMap.keySet();
  }
}