/**
 * Copyright (C) 2014 Stratio (http://stratio.com)
 *
 * 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.stratio.ingestion.sink.elasticsearch;

import org.elasticsearch.common.jackson.core.JsonParseException;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.common.xcontent.XContentParser;
import org.elasticsearch.common.xcontent.XContentType;

import java.io.IOException;
import java.nio.charset.Charset;

/**
 * Utility methods for using ElasticSearch {@link XContentBuilder}
 */
public class ContentBuilderUtil {

  private static final Charset charset = Charset.defaultCharset();

  private ContentBuilderUtil() {
  }

  public static void appendField(XContentBuilder builder, String field,
      byte[] data) throws IOException {
    XContentType contentType = XContentFactory.xContentType(data);
    if (contentType == null) {
      addSimpleField(builder, field, data);
    } else {
      addComplexField(builder, field, contentType, data);
    }
  }

  public static void addSimpleField(XContentBuilder builder, String fieldName,
      byte[] data) throws IOException {
    builder.field(fieldName, new String(data, charset));
  }

  public static void addComplexField(XContentBuilder builder, String fieldName,
      XContentType contentType, byte[] data) throws IOException {
    XContentParser parser = null;
    try {
      // Elasticsearch will accept JSON directly but we need to validate that
      // the incoming event is JSON first. Sadly, the elasticsearch JSON parser
      // is a stream parser so we need to instantiate it, parse the event to
      // validate it, then instantiate it again to provide the JSON to
      // elasticsearch.
      // If validation fails then the incoming event is submitted to
      // elasticsearch as plain text.
      parser = XContentFactory.xContent(contentType).createParser(data);
      while (parser.nextToken() != null) {};

      // If the JSON is valid then include it
      parser = XContentFactory.xContent(contentType).createParser(data);
      // Add the field name, but not the value.
      builder.field(fieldName);
      // This will add the whole parsed content as the value of the field.
      builder.copyCurrentStructure(parser);
    } catch (JsonParseException ex) {
      // If we get an exception here the most likely cause is nested JSON that
      // can't be figured out in the body. At this point just push it through
      // as is
      addSimpleField(builder, fieldName, data);
    } finally {
      if (parser != null) {
        parser.close();
      }
    }
  }
}
