/*-
 * -\-\-
 * Helios Services
 * --
 * Copyright (C) 2016 Spotify AB
 * --
 * Licensed 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 com.spotify.helios.servicescommon.coordination;

import org.apache.curator.utils.ZKPaths;
import org.apache.zookeeper.KeeperException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A best-effort ZooKeeper node updater.
 */
public class ZooKeeperNodeUpdater implements NodeUpdater {

  private static final Logger log = LoggerFactory.getLogger(ZooKeeperNodeUpdater.class);

  private final ZooKeeperClient zooKeeperClient;
  private final String path;

  public ZooKeeperNodeUpdater(final String path, final ZooKeeperClient zooKeeperClient) {
    this.zooKeeperClient = zooKeeperClient;
    this.path = path;
  }

  @Override
  public boolean update(final byte[] bytes) {
    final String parent = ZKPaths.getPathAndNode(path).getPath();
    try {
      if (zooKeeperClient.stat(parent) == null) {
        return false;
      }
      if (zooKeeperClient.stat(path) == null) {
        zooKeeperClient.createAndSetData(path, bytes);
      } else {
        zooKeeperClient.setData(path, bytes);
      }
      return true;
    } catch (KeeperException.NodeExistsException ignore) {
      // Conflict due to curator retry or losing a race. We're done here.
      return true;
    } catch (KeeperException.ConnectionLossException e) {
      log.warn("ZooKeeper connection lost while updating node: {}", path);
      return false;
    } catch (KeeperException e) {
      log.error("failed to update node: {}", path, e);
      return false;
    }
  }
}
