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   *  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
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   *    https://www.apache.org/licenses/LICENSE-2.0
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  package org.apache.cayenne.crypto.transformer;
  
  import org.apache.cayenne.access.jdbc.ColumnDescriptor;
  import org.apache.cayenne.access.translator.DbAttributeBinding;
  import org.apache.cayenne.access.types.ExtendedTypeMap;
  import org.apache.cayenne.crypto.map.ColumnMapper;
  import org.apache.cayenne.crypto.transformer.bytes.BytesTransformerFactory;
  import org.apache.cayenne.crypto.transformer.value.ValueDecryptor;
  import org.apache.cayenne.crypto.transformer.value.ValueEncryptor;
  import org.apache.cayenne.crypto.transformer.value.ValueTransformerFactory;
  import org.apache.cayenne.di.Inject;
  import org.apache.cayenne.map.DbAttribute;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  /**
   * @since 4.0
   */
  public class DefaultTransformerFactory implements TransformerFactory {
  
      private BytesTransformerFactory bytesTransformerFactory;
      private ColumnMapper columnMapper;
      private ValueTransformerFactory transformerFactory;
  
      public DefaultTransformerFactory(@Inject ColumnMapper columnMapper,
              @Inject ValueTransformerFactory transformerFactory, @Inject BytesTransformerFactory bytesTransformerFactory) {
          this.columnMapper = columnMapper;
          this.transformerFactory = transformerFactory;
          this.bytesTransformerFactory = bytesTransformerFactory;
      }
  
      @Override
      public MapTransformer decryptor(ColumnDescriptor[] columns, Object sampleRow) {
  
          if (!(sampleRow instanceof Map)) {
              return null;
          }
  
          int len = columns.length;
          List<Integer> cryptoColumns = null;
  
          for (int i = 0; i < len; i++) {
  
              DbAttribute a = columns[i].getAttribute();
              if (a != null && columnMapper.isEncrypted(a)) {
                  if (cryptoColumns == null) {
                      cryptoColumns = new ArrayList<>(len - i);
                  }
  
                  cryptoColumns.add(i);
              }
          }
  
          if (cryptoColumns != null) {
  
              int dlen = cryptoColumns.size();
              String[] mapKeys = new String[dlen];
              ValueDecryptor[] transformers = new ValueDecryptor[dlen];
  
              for (int i = 0; i < dlen; i++) {
  
                  ColumnDescriptor cd = columns[cryptoColumns.get(i)];
                  mapKeys[i] = cd.getDataRowKey();
                  transformers[i] = transformerFactory.decryptor(cd.getAttribute());
              }
  
              return new DefaultMapTransformer(mapKeys, transformers, bytesTransformerFactory.decryptor());
          }
  
          return null;
      }
  
      @Override
      public BindingsTransformer encryptor(DbAttributeBinding[] bindings, ExtendedTypeMap extendedTypeMap) {
          int len = bindings.length;
          List<Integer> cryptoColumns = null;
  
          for (int i = 0; i < len; i++) {
  
              DbAttribute a = bindings[i].getAttribute();
              if (columnMapper.isEncrypted(a)) {
  
                  if (cryptoColumns == null) {
                      cryptoColumns = new ArrayList<>(len - i);
                  }
  
                  cryptoColumns.add(i);
              }
          }
  
          if (cryptoColumns != null) {
  
              int dlen = cryptoColumns.size();
              int[] positions = new int[dlen];
              ValueEncryptor[] transformers = new ValueEncryptor[dlen];
  
              for (int i = 0; i < dlen; i++) {
                  int pos = cryptoColumns.get(i);
                  DbAttributeBinding b = bindings[pos];
                  positions[i] = pos;
                  transformers[i] = transformerFactory.encryptor(b.getAttribute());
              }
  
              return new DefaultBindingsTransformer(positions, transformers, bytesTransformerFactory.encryptor(), extendedTypeMap);
          }
  
          return null;
      }
  
  }
  