content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * 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.alibaba.nacos.client.config.impl;
  
  import com.alibaba.nacos.api.config.ConfigChangeItem;
  import com.alibaba.nacos.api.exception.NacosException;
  import com.alibaba.nacos.api.exception.runtime.NacosRuntimeException;
  import com.alibaba.nacos.common.utils.StringUtils;
  import org.yaml.snakeyaml.LoaderOptions;
  import org.yaml.snakeyaml.Yaml;
  import org.yaml.snakeyaml.composer.ComposerException;
  import org.yaml.snakeyaml.constructor.SafeConstructor;
  import org.yaml.snakeyaml.error.MarkedYAMLException;
  
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.LinkedHashMap;
  import java.util.Map;
  
  /**
   * YmlChangeParser.
   *
   * @author rushsky518
   */
  public class YmlChangeParser extends AbstractConfigChangeParser {
      
      private static final String INVALID_CONSTRUCTOR_ERROR_INFO = "could not determine a constructor for the tag";
      
      private static final String CONFIG_TYPE = "yaml";
      
      public YmlChangeParser() {
          super(CONFIG_TYPE);
      }
      
      @Override
      public Map<String, ConfigChangeItem> doParse(String oldContent, String newContent, String type) {
          Map<String, Object> oldMap = Collections.emptyMap();
          Map<String, Object> newMap = Collections.emptyMap();
          try {
              Yaml yaml = new Yaml(new SafeConstructor(new LoaderOptions()));
              if (StringUtils.isNotBlank(oldContent)) {
                  oldMap = yaml.load(oldContent);
                  oldMap = getFlattenedMap(oldMap);
              }
              if (StringUtils.isNotBlank(newContent)) {
                  newMap = yaml.load(newContent);
                  newMap = getFlattenedMap(newMap);
              }
          } catch (MarkedYAMLException e) {
              handleYamlException(e);
          }
          
          return filterChangeData(oldMap, newMap);
      }
      
      private void handleYamlException(MarkedYAMLException e) {
          if (e.getMessage().startsWith(INVALID_CONSTRUCTOR_ERROR_INFO) || e instanceof ComposerException) {
              throw new NacosRuntimeException(NacosException.INVALID_PARAM,
                      "AbstractConfigChangeListener only support basic java data type for yaml. If you want to listen "
                              + "key changes for custom classes, please use `Listener` to listener whole yaml configuration and parse it by yourself.",
                      e);
          }
          throw e;
      }
      
      private Map<String, Object> getFlattenedMap(Map<String, Object> source) {
          Map<String, Object> result = new LinkedHashMap<>(128);
          buildFlattenedMap(result, source, null);
          return result;
      }
      
      private void buildFlattenedMap(Map<String, Object> result, Map<String, Object> source, String path) {
          for (Iterator<Map.Entry<String, Object>> itr = source.entrySet().iterator(); itr.hasNext(); ) {
              Map.Entry<String, Object> e = itr.next();
              String key = e.getKey();
              if (StringUtils.isNotBlank(path)) {
                  if (e.getKey().startsWith("[")) {
                      key = path + key;
                  } else {
                      key = path + '.' + key;
                  }
              }
              if (e.getValue() instanceof String) {
                  result.put(key, e.getValue());
              } else if (e.getValue() instanceof Map) {
                  @SuppressWarnings("unchecked") Map<String, Object> map = (Map<String, Object>) e.getValue();
                  buildFlattenedMap(result, map, key);
              } else if (e.getValue() instanceof Collection) {
                  @SuppressWarnings("unchecked") Collection<Object> collection = (Collection<Object>) e.getValue();
                  if (collection.isEmpty()) {
                      result.put(key, "");
                  } else {
                      int count = 0;
                      for (Object object : collection) {
                          buildFlattenedMap(result, Collections.singletonMap("[" + (count++) + "]", object), key);
                      }
                  }
              } else {
                  result.put(key, (e.getValue() != null ? e.getValue() : ""));
              }
          }
      }
      
  }
  