/*
 * 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.phoenix.util;

import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Properties;
import java.util.Set;
import org.apache.hadoop.conf.Configuration;

public class PropertiesUtil {

  private PropertiesUtil() {
  }

  /**
   * Use this to deep copy properties. The copy constructor in {@link java.util.Properties} does not
   * do a deep copy.
   * @return new mutable instance of Properties populated with values from the passed in Properties.
   */
  public static Properties deepCopy(Properties properties) {
    Properties newProperties = new Properties();
    for (String pName : properties.stringPropertyNames()) {
      newProperties.setProperty(pName, properties.getProperty(pName));
    }
    return newProperties;
  }

  /**
   * Add properties from the given Configuration to the provided Properties. Note that only those
   * configuration properties will be added to the provided properties whose values are already not
   * set. The method doesn't modify the passed in properties instead makes a clone of them before
   * combining.
   * @return properties object that is a combination of properties contained in props and properties
   *         contained in conf
   */
  public static Properties combineProperties(Properties props, final Configuration conf) {
    return combineProperties(props, conf, Collections.<String> emptySet());
  }

  public static Properties combineProperties(Properties props, final Configuration conf,
    Set<String> withoutTheseProps) {
    Iterator<Map.Entry<String, String>> iterator = conf.iterator();
    Properties copy = deepCopy(props);
    if (iterator != null) {
      while (iterator.hasNext()) {
        Map.Entry<String, String> entry = iterator.next();
        // set the property from config only if props doesn't have it already
        if (
          copy.getProperty(entry.getKey()) == null && !withoutTheseProps.contains(entry.getKey())
        ) {
          copy.setProperty(entry.getKey(), entry.getValue());
        }
      }
    }
    return copy;
  }

  /**
   * Utility to work around the limitation of the copy constructor
   * {@link Configuration#Configuration(Configuration)} provided by the {@link Configuration} class.
   * See https://issues.apache.org/jira/browse/HBASE-18378. The copy constructor doesn't copy all
   * the config settings, so we need to resort to iterating through all the settings and setting it
   * on the cloned config.
   * @param toCopy configuration to copy
   */
  public static Configuration cloneConfig(Configuration toCopy) {
    Configuration clone = new Configuration();
    Iterator<Entry<String, String>> iterator = toCopy.iterator();
    while (iterator.hasNext()) {
      Entry<String, String> entry = iterator.next();
      clone.set(entry.getKey(), entry.getValue());
    }
    return clone;
  }
}
