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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Metamarkets 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 io.druid.java.util.common.parsers;


import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.base.Charsets;
import com.google.common.base.Function;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;

import java.nio.charset.CharsetEncoder;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class JSONParser implements Parser
{
  public static final Function valueFunction = new Function()
  {
    @Override
    public Object apply(JsonNode node)
    {
      if (node == null || node.isMissingNode() || node.isNull()) {
        return null;
      }
      if (node.isIntegralNumber()) {
        if (node.canConvertToLong()) {
          return node.asLong();
        } else {
          return node.asDouble();
        }
      }
      if (node.isFloatingPointNumber()) {
        return node.asDouble();
      }
      final String s = node.asText();
      final CharsetEncoder enc = Charsets.UTF_8.newEncoder();
      if (s != null && !enc.canEncode(s)) {
        // Some whacky characters are in this string (e.g. \uD900). These are problematic because they are decodeable
        // by new String(...) but will not encode into the same character. This dance here will replace these
        // characters with something more sane.
        return new String(s.getBytes(Charsets.UTF_8), Charsets.UTF_8);
      } else {
        return s;
      }
    }
  };

  private final ObjectMapper objectMapper;
  private ArrayList fieldNames;
  private final Set exclude;

  public JSONParser()
  {
    this(new ObjectMapper(), null, null);
  }

  @Deprecated
  public JSONParser(Iterable fieldNames)
  {
    this(new ObjectMapper(), fieldNames, null);
  }

  public JSONParser(ObjectMapper objectMapper, Iterable fieldNames)
  {
    this(objectMapper, fieldNames, null);
  }

  public JSONParser(ObjectMapper objectMapper, Iterable fieldNames, Iterable exclude)
  {
    this.objectMapper = objectMapper;
    if (fieldNames != null) {
      setFieldNames(fieldNames);
    }
    this.exclude = exclude != null ? Sets.newHashSet(exclude) : Sets.newHashSet();
  }

  @Override
  public List getFieldNames()
  {
    return fieldNames;
  }

  @Override
  public void setFieldNames(Iterable fieldNames)
  {
    ParserUtils.validateFields(fieldNames);
    this.fieldNames = Lists.newArrayList(fieldNames);
  }

  @Override
  public Map parse(String input)
  {
    try {
      Map map = new LinkedHashMap<>();
      JsonNode root = objectMapper.readTree(input);

      Iterator keysIter = (fieldNames == null ? root.fieldNames() : fieldNames.iterator());

      while (keysIter.hasNext()) {
        String key = keysIter.next();

        if (exclude.contains(key)) {
          continue;
        }

        JsonNode node = root.path(key);

        if (node.isArray()) {
          final List