/*
 * 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.servicecomb.config.center.client;

import java.util.Map;

import org.apache.servicecomb.config.center.client.model.QueryConfigurationsRequest;
import org.apache.servicecomb.config.center.client.model.QueryConfigurationsResponse;
import org.apache.servicecomb.config.common.ConfigConverter;
import org.apache.servicecomb.config.common.ConfigurationChangedEvent;
import org.apache.servicecomb.http.client.task.AbstractTask;
import org.apache.servicecomb.http.client.task.Task;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.eventbus.EventBus;

public class ConfigCenterManager extends AbstractTask {

  private static final Logger LOGGER = LoggerFactory.getLogger(ConfigCenterManager.class);

  private static final long POLL_INTERVAL = 15000;

  private final ConfigCenterClient configCenterClient;

  private final EventBus eventBus;

  private QueryConfigurationsRequest queryConfigurationsRequest;

  private final ConfigConverter configConverter;

  public ConfigCenterManager(ConfigCenterClient configCenterClient, EventBus eventBus,
      ConfigConverter configConverter) {
    super("config-center-configuration-task");
    this.configCenterClient = configCenterClient;
    this.eventBus = eventBus;
    this.configConverter = configConverter;
  }

  public void setQueryConfigurationsRequest(QueryConfigurationsRequest queryConfigurationsRequest) {
    this.queryConfigurationsRequest = queryConfigurationsRequest;
  }

  public void startConfigCenterManager() {
    this.startTask(new PollConfigurationTask(0));
  }

  class PollConfigurationTask implements Task {
    int failCount;

    public PollConfigurationTask(int failCount) {
      this.failCount = failCount;
    }

    @Override
    public void execute() {
      try {
        QueryConfigurationsResponse response = configCenterClient.queryConfigurations(queryConfigurationsRequest);
        if (response.isChanged()) {
          queryConfigurationsRequest.setRevision(response.getRevision());
          Map<String, Object> lastData = configConverter.updateData(response.getConfigurations());
          ConfigurationChangedEvent event = ConfigurationChangedEvent
              .createIncremental(configConverter.getCurrentData(), lastData);
          eventBus.post(event);
        }
        startTask(new BackOffSleepTask(POLL_INTERVAL, new PollConfigurationTask(0)));
      } catch (Exception e) {
        LOGGER.error("get configurations from ConfigCenter failed, and will try again.", e);
        startTask(new BackOffSleepTask(failCount + 1, new PollConfigurationTask(failCount + 1)));
      }
    }
  }
}
