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/**
 * Copyright 2015 Thomas Feng
 *
 * 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 me.tfeng.toolbox.mongodb;

import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.apache.avro.Schema;
import org.apache.avro.Schema.Field;
import org.apache.avro.Schema.Type;
import org.apache.avro.generic.GenericData.Record;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.IndexedRecord;
import org.apache.avro.io.Decoder;
import org.apache.avro.specific.SpecificDatumReader;
import org.bson.BSONObject;
import org.bson.Document;
import org.bson.types.Binary;
import org.mortbay.util.ajax.JSON;

/**
 * @author Thomas Feng ([email protected])
 */
public class RecordConverter {

  public static final String MONGO_CLASS_PROPERTY = "mongo-class";

  public static final String MONGO_NAME_PROPERTY = "mongo-name";

  public static final String MONGO_TYPE_PROPERTY = "mongo-type";

  public static Document toDocument(IndexedRecord record) {
    Document document = new Document();
    Schema schema = record.getSchema();
    for (Field field : schema.getFields()) {
      Object value = record.get(field.pos());
      if (value != null) {
        document.put(getFieldName(field), getDocument(field.schema(), value));
      }
    }
    return document;
  }

  public static  T toRecord(Class recordClass, BSONObject object) {
    SpecificDatumReader reader = new SpecificDatumReader(recordClass);
    try {
      Decoder decoder = new DocumentDecoder(recordClass, object);
      return reader.read(null, decoder);
    } catch (IOException e) {
      throw new RuntimeException("Unable to convert MongoDB object " + object + " into Avro record", e);
    }
  }

  public static  T toRecord(Class recordClass, Document document) {
    SpecificDatumReader reader = new SpecificDatumReader(recordClass);
    try {
      Decoder decoder = new DocumentDecoder(recordClass, document);
      return reader.read(null, decoder);
    } catch (IOException e) {
      throw new RuntimeException("Unable to convert MongoDB document " + document + " into Avro record", e);
    }
  }

  public static Record toRecord(Schema schema, BSONObject object, ClassLoader classLoader) throws IOException {
    GenericDatumReader reader = new GenericDatumReader<>(schema);
    return reader.read(null, new DocumentDecoder(schema, object, classLoader));
  }

  public static Record toRecord(Schema schema, Document document, ClassLoader classLoader) throws IOException {
    GenericDatumReader reader = new GenericDatumReader<>(schema);
    return reader.read(null, new DocumentDecoder(schema, document, classLoader));
  }

  protected static String getFieldName(Field field) {
    String mongoName = field.getProp(MONGO_NAME_PROPERTY);
    if (mongoName != null) {
      return mongoName;
    } else {
      return field.name();
    }
  }

  @SuppressWarnings("unchecked")
  private static Object getDocument(Schema schema, Object object) {
    if (schema.getType() == Type.UNION) {
      List types = schema.getTypes();
      if (types.size() != 2 && types.get(0).getType() != Type.NULL && types.get(1).getType() != Type.NULL) {
        throw new RuntimeException("In a union type, only null unioned with exactly one other type is supported: "
                + schema);
      }
      if (types.get(0).getType() == Type.NULL) {
        return getDocument(types.get(1), object);
      } else {
        return getDocument(types.get(0), object);
      }
    } else if (object == null) {
      return null;
    } else if (object instanceof IndexedRecord) {
      return toDocument((IndexedRecord) object);
    } else if (object instanceof Collection) {
      return getDocuments(schema, (Collection