/*
 * 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.ambari.logsearch.handler;

import org.apache.ambari.logsearch.conf.SolrPropsConfig;
import org.apache.commons.io.FileUtils;
import org.apache.solr.client.solrj.impl.CloudSolrClient;
import org.apache.solr.common.cloud.SolrZkClient;
import org.apache.solr.common.cloud.ZkConfigManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Paths;
import java.util.UUID;

public abstract class AbstractSolrConfigHandler implements SolrZkRequestHandler<Boolean> {

  private static final Logger LOG = LoggerFactory.getLogger(AbstractSolrConfigHandler.class);

  private File configSetFolder;

  public AbstractSolrConfigHandler(File configSetFolder) {
    this.configSetFolder = configSetFolder;
  }

  @Override
  public Boolean handle(CloudSolrClient solrClient, SolrPropsConfig solrPropsConfig) throws Exception {
    boolean reloadCollectionNeeded = false;
    String separator = FileSystems.getDefault().getSeparator();
    String downloadFolderLocation = String.format("%s%s%s%s%s", System.getProperty("java.io.tmpdir"), separator,
      UUID.randomUUID().toString(), separator, solrPropsConfig.getConfigName());
    solrClient.connect();
    SolrZkClient zkClient = solrClient.getZkStateReader().getZkClient();
    File tmpDir = new File(downloadFolderLocation);
    try {
      ZkConfigManager zkConfigManager = new ZkConfigManager(zkClient);
      boolean configExists = zkConfigManager.configExists(solrPropsConfig.getConfigName());
      if (configExists) {
        uploadMissingConfigFiles(zkClient, zkConfigManager, solrPropsConfig.getConfigName());
        reloadCollectionNeeded = doIfConfigExists(solrPropsConfig, zkClient, separator, downloadFolderLocation, tmpDir);
      } else {
        doIfConfigNotExist(solrPropsConfig, zkConfigManager);
        uploadMissingConfigFiles(zkClient, zkConfigManager, solrPropsConfig.getConfigName());
      }
    } catch (Exception e) {
      throw new RuntimeException(String.format("Cannot upload configurations to zk. (collection: %s, config set folder: %s)",
        solrPropsConfig.getCollection(), solrPropsConfig.getConfigSetFolder()), e);
    } finally {
      if (tmpDir.exists()) {
        try {
          FileUtils.deleteDirectory(tmpDir);
        } catch (IOException e){
          LOG.error("Cannot delete temp directory.", e);
        }
      }
    }
    return reloadCollectionNeeded;
  }

  /**
   * Update config file (like solrconfig.xml) to zookeeper znode of solr, contains a download location as well which can be
   * used to determine that you need to update the configuration or not
   */
  public abstract boolean updateConfigIfNeeded(SolrPropsConfig solrPropsConfig, SolrZkClient zkClient, File file,
                                               String separator, String downloadFolderLocation) throws IOException;

  /**
   * Config file name which should be uploaded to zookeeper
   */
  public abstract String getConfigFileName();

  public void doIfConfigNotExist(SolrPropsConfig solrPropsConfig, ZkConfigManager zkConfigManager) throws IOException {
    // Do nothing
  };

  public void uploadMissingConfigFiles(SolrZkClient zkClient, ZkConfigManager zkConfigManager, String configName) throws IOException {
    // do Nothing
  }

  public boolean doIfConfigExists(SolrPropsConfig solrPropsConfig, SolrZkClient zkClient, String separator, String downloadFolderLocation, File tmpDir) throws IOException {
    boolean result = false;
    LOG.info("Config set exists for '{}' collection. Refreshing it if needed...", solrPropsConfig.getCollection());
    if (!tmpDir.mkdirs()) {
      LOG.error("Cannot create directories for '{}'", tmpDir.getAbsolutePath());
    }
    ZkConfigManager zkConfigManager = new ZkConfigManager(zkClient);
    zkConfigManager.downloadConfigDir(solrPropsConfig.getConfigName(), Paths.get(downloadFolderLocation));
    File[] listOfFiles = getConfigSetFolder().listFiles();
    if (listOfFiles != null) {
      for (File file : listOfFiles) {
        if (file.getName().equals(getConfigFileName()) && updateConfigIfNeeded(solrPropsConfig, zkClient, file, separator, downloadFolderLocation)) {
          result = true;
          break;
        }
      }
    }
    return result;
  }

  protected File getConfigSetFolder() {
    return configSetFolder;
  }
}