/*
    * 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.syncope.common.keymaster.client.zookeeper;
  
  import com.fasterxml.jackson.databind.json.JsonMapper;
  import java.util.Map;
  import java.util.Optional;
  import java.util.TreeMap;
  import org.apache.curator.framework.CuratorFramework;
  import org.apache.syncope.common.keymaster.client.api.ConfParamOps;
  import org.apache.syncope.common.keymaster.client.api.KeymasterException;
  import org.apache.zookeeper.KeeperException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Implements {@link ConfParamOps} via Apache Curator / Zookeeper.
   */
  public class ZookeeperConfParamOps implements ConfParamOps {
  
      protected static final Logger LOG = LoggerFactory.getLogger(ConfParamOps.class);
  
      protected static final JsonMapper MAPPER = JsonMapper.builder().findAndAddModules().build();
  
      protected static final String CONF_PATH = "/conf";
  
      protected final CuratorFramework client;
  
      protected static String buildConfPath(final String... parts) {
          return CONF_PATH + '/' + String.join("/", parts);
      }
  
      public ZookeeperConfParamOps(final CuratorFramework client) {
          this.client = client;
      }
  
      @Override
      public Map<String, Object> list(final String domain) {
          try {
              if (client.checkExists().forPath(buildConfPath(domain)) == null) {
                  client.create().creatingParentContainersIfNeeded().forPath(buildConfPath(domain));
              }
  
              Map<String, Object> list = new TreeMap<>();
              for (String child : client.getChildren().forPath(buildConfPath(domain))) {
                  list.put(child, MAPPER.readValue(client.getData().forPath(buildConfPath(domain, child)), Object.class));
              }
  
              return list;
          } catch (Exception e) {
              throw new KeymasterException(e);
          }
      }
  
      @Override
      public <T> T get(final String domain, final String key, final T defaultValue, final Class<T> reference) {
          T value = null;
          try {
              value = MAPPER.readValue(client.getData().forPath(buildConfPath(domain, key)), reference);
          } catch (KeeperException.NoNodeException e) {
              LOG.debug("Node {} was not found", buildConfPath(domain, key));
          } catch (Exception e) {
              throw new KeymasterException(e);
          }
  
          return Optional.ofNullable(value).orElse(defaultValue);
      }
  
      @Override
      public <T> void set(final String domain, final String key, final T value) {
          if (value == null) {
              remove(domain, key);
          } else {
              try {
                  if (client.checkExists().forPath(buildConfPath(domain, key)) == null) {
                      client.create().creatingParentContainersIfNeeded().forPath(buildConfPath(domain, key));
                  }
  
                  client.setData().forPath(buildConfPath(domain, key), MAPPER.writeValueAsBytes(value));
              } catch (Exception e) {
                  throw new KeymasterException(e);
              }
          }
     }
 
     @Override
     public void remove(final String domain, final String key) {
         try {
             client.delete().forPath(buildConfPath(domain, key));
         } catch (Exception e) {
             throw new KeymasterException(e);
         }
     }
 }