content: /*
   * 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 org.apache.kafka.connect.transforms;
  
  import org.apache.kafka.common.config.ConfigDef;
  import org.apache.kafka.common.utils.AppInfoParser;
  import org.apache.kafka.connect.components.Versioned;
  import org.apache.kafka.connect.connector.ConnectRecord;
  import org.apache.kafka.connect.data.Field;
  import org.apache.kafka.connect.data.Schema;
  import org.apache.kafka.connect.data.Struct;
  import org.apache.kafka.connect.data.Values;
  import org.apache.kafka.connect.errors.DataException;
  import org.apache.kafka.connect.transforms.util.NonEmptyListValidator;
  import org.apache.kafka.connect.transforms.util.SimpleConfig;
  
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.util.ArrayList;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.function.Function;
  
  import static org.apache.kafka.connect.transforms.util.Requirements.requireMap;
  import static org.apache.kafka.connect.transforms.util.Requirements.requireStruct;
  
  public abstract class MaskField<R extends ConnectRecord<R>> implements Transformation<R>, Versioned {
  
      public static final String OVERVIEW_DOC =
              "Mask specified fields with a valid null value for the field type (i.e. 0, false, empty string, and so on)."
                      + "<p/>For numeric and string fields, an optional replacement value can be specified that is converted to the correct type."
                      + "<p/>Use the concrete transformation type designed for the record key (<code>" + Key.class.getName()
                      + "</code>) or value (<code>" + Value.class.getName() + "</code>).";
  
      private static final String FIELDS_CONFIG = "fields";
      private static final String REPLACEMENT_CONFIG = "replacement";
      private static final String REPLACE_NULL_WITH_DEFAULT_CONFIG = "replace.null.with.default";
  
      public static final ConfigDef CONFIG_DEF = new ConfigDef()
              .define(FIELDS_CONFIG, ConfigDef.Type.LIST, ConfigDef.NO_DEFAULT_VALUE, new NonEmptyListValidator(),
                      ConfigDef.Importance.HIGH, "Names of fields to mask.")
              .define(REPLACEMENT_CONFIG, ConfigDef.Type.STRING, null, new ConfigDef.NonEmptyString(),
                      ConfigDef.Importance.LOW, "Custom value replacement, that will be applied to all"
                              + " 'fields' values (numeric or non-empty string values only).")
              .define(REPLACE_NULL_WITH_DEFAULT_CONFIG, ConfigDef.Type.BOOLEAN, true, ConfigDef.Importance.MEDIUM,
                      "Whether to replace fields that have a default value and that are null to the default value. When set to true, the default value is used, otherwise null is used.");
  
      private static final String PURPOSE = "mask fields";
  
      private static final Map<Class<?>, Function<String, ?>> REPLACEMENT_MAPPING_FUNC = new HashMap<>();
      private static final Map<Class<?>, Object> PRIMITIVE_VALUE_MAPPING = new HashMap<>();
  
      static {
          PRIMITIVE_VALUE_MAPPING.put(Boolean.class, Boolean.FALSE);
          PRIMITIVE_VALUE_MAPPING.put(Byte.class, (byte) 0);
          PRIMITIVE_VALUE_MAPPING.put(Short.class, (short) 0);
          PRIMITIVE_VALUE_MAPPING.put(Integer.class, 0);
          PRIMITIVE_VALUE_MAPPING.put(Long.class, 0L);
          PRIMITIVE_VALUE_MAPPING.put(Float.class, 0f);
          PRIMITIVE_VALUE_MAPPING.put(Double.class, 0d);
          PRIMITIVE_VALUE_MAPPING.put(BigInteger.class, BigInteger.ZERO);
          PRIMITIVE_VALUE_MAPPING.put(BigDecimal.class, BigDecimal.ZERO);
          PRIMITIVE_VALUE_MAPPING.put(Date.class, new Date(0));
          PRIMITIVE_VALUE_MAPPING.put(String.class, "");
  
          REPLACEMENT_MAPPING_FUNC.put(Byte.class, v -> Values.convertToByte(null, v));
          REPLACEMENT_MAPPING_FUNC.put(Short.class, v -> Values.convertToShort(null, v));
          REPLACEMENT_MAPPING_FUNC.put(Integer.class, v -> Values.convertToInteger(null, v));
          REPLACEMENT_MAPPING_FUNC.put(Long.class, v -> Values.convertToLong(null, v));
          REPLACEMENT_MAPPING_FUNC.put(Float.class, v -> Values.convertToFloat(null, v));
          REPLACEMENT_MAPPING_FUNC.put(Double.class, v -> Values.convertToDouble(null, v));
          REPLACEMENT_MAPPING_FUNC.put(String.class, Function.identity());
          REPLACEMENT_MAPPING_FUNC.put(BigDecimal.class, BigDecimal::new);
          REPLACEMENT_MAPPING_FUNC.put(BigInteger.class, BigInteger::new);
      }
  
      private Set<String> maskedFields;
      private String replacement;
      private boolean replaceNullWithDefault;
  
      @Override
      public String version() {
          return AppInfoParser.getVersion();
      }
  
      @Override
      public void configure(Map<String, ?> props) {
          final SimpleConfig config = new SimpleConfig(CONFIG_DEF, props);
          maskedFields = new HashSet<>(config.getList(FIELDS_CONFIG));
          replacement = config.getString(REPLACEMENT_CONFIG);
          replaceNullWithDefault = config.getBoolean(REPLACE_NULL_WITH_DEFAULT_CONFIG);
      }
  
      @Override
      public R apply(R record) {
          if (operatingSchema(record) == null) {
              return applySchemaless(record);
          } else {
              return applyWithSchema(record);
          }
      }
  
      private R applySchemaless(R record) {
          final Map<String, Object> value = requireMap(operatingValue(record), PURPOSE);
          final HashMap<String, Object> updatedValue = new HashMap<>(value);
          for (String field : maskedFields) {
              updatedValue.put(field, masked(value.get(field)));
          }
          return newRecord(record, updatedValue);
      }
  
      private R applyWithSchema(R record) {
          final Struct value = requireStruct(operatingValue(record), PURPOSE);
          final Struct updatedValue = new Struct(value.schema());
          for (Field field : value.schema().fields()) {
              final Object origFieldValue = getFieldValue(value, field);
              updatedValue.put(field, maskedFields.contains(field.name()) ? masked(origFieldValue) : origFieldValue);
          }
          return newRecord(record, updatedValue);
      }
  
      private Object getFieldValue(Struct value, Field field) {
          if (replaceNullWithDefault) {
              return value.get(field);
          }
          return value.getWithoutDefault(field.name());
      }
  
      private Object masked(Object value) {
          if (value == null) {
              return null;
          }
          return replacement == null ? maskWithNullValue(value) : maskWithCustomReplacement(value, replacement);
      }
  
      private static Object maskWithCustomReplacement(Object value, String replacement) {
          Function<String, ?> replacementMapper = REPLACEMENT_MAPPING_FUNC.get(value.getClass());
          if (replacementMapper == null) {
              throw new DataException("Cannot mask value of type " + value.getClass() + " with custom replacement.");
          }
          try {
              return replacementMapper.apply(replacement);
          } catch (NumberFormatException ex) {
              throw new DataException("Unable to convert " + replacement + " (" + replacement.getClass() + ") to number", ex);
          }
      }
  
      private static Object maskWithNullValue(Object value) {
          Object maskedValue = PRIMITIVE_VALUE_MAPPING.get(value.getClass());
          if (maskedValue == null) {
              if (value instanceof List)
                  maskedValue = new ArrayList<>();
              else if (value instanceof Map)
                  maskedValue = new HashMap<>();
              else
                  throw new DataException("Cannot mask value of type: " + value.getClass());
          }
          return maskedValue;
      }
  
      @Override
      public ConfigDef config() {
          return CONFIG_DEF;
      }
  
      @Override
      public void close() {
      }
  
      protected abstract Schema operatingSchema(R record);
  
      protected abstract Object operatingValue(R record);
  
      protected abstract R newRecord(R base, Object value);
  
      public static final class Key<R extends ConnectRecord<R>> extends MaskField<R> {
          @Override
          protected Schema operatingSchema(R record) {
              return record.keySchema();
          }
  
          @Override
          protected Object operatingValue(R record) {
              return record.key();
          }
  
          @Override
          protected R newRecord(R record, Object updatedValue) {
              return record.newRecord(record.topic(), record.kafkaPartition(), record.keySchema(), updatedValue, record.valueSchema(), record.value(), record.timestamp());
          }
      }
  
      public static final class Value<R extends ConnectRecord<R>> extends MaskField<R> {
          @Override
          protected Schema operatingSchema(R record) {
              return record.valueSchema();
          }
  
          @Override
          protected Object operatingValue(R record) {
              return record.value();
          }
  
          @Override
          protected R newRecord(R record, Object updatedValue) {
              return record.newRecord(record.topic(), record.kafkaPartition(), record.keySchema(), record.key(), record.valueSchema(), updatedValue, record.timestamp());
          }
      }
  
  }
  