content: /*
   * Copyright 2014-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License").
   * You may not use this file except in compliance with the License.
   * A copy of the License is located at
   *
   *  http://aws.amazon.com/apache2.0
   *
   * or in the "license" file accompanying this file. This file 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.amazon.janusgraph.diskstorage.dynamodb.builder;
  
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  import java.util.Map;
  
  import org.apache.commons.codec.DecoderException;
  import org.apache.commons.codec.binary.Hex;
  import org.janusgraph.diskstorage.StaticBuffer;
  import org.janusgraph.diskstorage.util.BufferUtil;
  import org.janusgraph.diskstorage.util.StaticArrayBuffer;
  
  import com.amazon.janusgraph.diskstorage.dynamodb.Constants;
  import com.amazonaws.services.dynamodbv2.model.AttributeValue;
  
  /**
   * AbstractBuilder is responsible for some of the StaticBuffer to String and
   * visa-versa required for working with the database.
   *
   * @author Matthew Sowders
   * @author Alexander Patrikalakis
   *
   */
  public abstract class AbstractBuilder {
  
      protected AttributeValue encodeKeyAsAttributeValue(final StaticBuffer input) {
          return new AttributeValue().withS(encodeKeyBuffer(input));
      }
  
      public static String encodeKeyBuffer(final StaticBuffer input) {
          if (input == null || input.length() == 0) {
              return null;
          }
          final ByteBuffer buf = input.asByteBuffer();
          final byte[] bytes = Arrays.copyOf(buf.array(), buf.limit());
          return Hex.encodeHexString(bytes);
      }
  
      protected AttributeValue encodeValue(final StaticBuffer value) {
          // Dynamo does not allow empty binary values, so we use a placeholder
          // for empty values
          if (value.length() <= 0) {
              return new AttributeValue().withS(Constants.EMPTY_BUFFER_PLACEHOLDER);
          }
          return new AttributeValue().withB(value.asByteBuffer());
      }
  
      protected StaticBuffer decodeValue(final AttributeValue val) {
          if (null == val) {
              return null;
          }
          // Dynamo does not allow empty binary values, so we use a placeholder
          // for empty values
          if (Constants.EMPTY_BUFFER_PLACEHOLDER.equals(val.getS())) {
              return BufferUtil.emptyBuffer();
          }
          return StaticArrayBuffer.of(val.getB());
      }
  
      protected StaticBuffer decodeKey(final Map<String, AttributeValue> key, final String name) {
          if (null == key || !key.containsKey(name)) {
              return null;
          }
          final AttributeValue attributeValue = key.get(name);
          final String value = attributeValue.getS();
          return decodeKey(value);
      }
  
      public static StaticBuffer decodeKey(final String name) {
          try {
              return new StaticArrayBuffer(Hex.decodeHex(name.toCharArray()));
          } catch (DecoderException e) {
              throw new RuntimeException(e);
          }
      }
  }
  