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   * 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.
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  package org.apache.beam.sdk.schemas;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import org.apache.beam.sdk.coders.BigDecimalCoder;
  import org.apache.beam.sdk.coders.BigEndianShortCoder;
  import org.apache.beam.sdk.coders.BooleanCoder;
  import org.apache.beam.sdk.coders.ByteArrayCoder;
  import org.apache.beam.sdk.coders.ByteCoder;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.coders.CoderException;
  import org.apache.beam.sdk.coders.DoubleCoder;
  import org.apache.beam.sdk.coders.FloatCoder;
  import org.apache.beam.sdk.coders.InstantCoder;
  import org.apache.beam.sdk.coders.IterableCoder;
  import org.apache.beam.sdk.coders.ListCoder;
  import org.apache.beam.sdk.coders.MapCoder;
  import org.apache.beam.sdk.coders.NullableCoder;
  import org.apache.beam.sdk.coders.StringUtf8Coder;
  import org.apache.beam.sdk.coders.VarIntCoder;
  import org.apache.beam.sdk.coders.VarLongCoder;
  import org.apache.beam.sdk.schemas.Schema.FieldType;
  import org.apache.beam.sdk.schemas.Schema.LogicalType;
  import org.apache.beam.sdk.schemas.Schema.TypeName;
  import org.apache.beam.sdk.util.common.ElementByteSizeObserver;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableMap;
  import org.joda.time.ReadableInstant;
  
  @SuppressWarnings({
    "nullness", // TODO(https://github.com/apache/beam/issues/20497)
    "rawtypes"
  })
  class SchemaCoderHelpers {
    // This contains a map of primitive types to their coders.
    private static final Map<TypeName, Coder> CODER_MAP =
        ImmutableMap.<TypeName, Coder>builder()
            .put(TypeName.BYTE, ByteCoder.of())
            .put(TypeName.BYTES, ByteArrayCoder.of())
            .put(TypeName.INT16, BigEndianShortCoder.of())
            .put(TypeName.INT32, VarIntCoder.of())
            .put(TypeName.INT64, VarLongCoder.of())
            .put(TypeName.DECIMAL, BigDecimalCoder.of())
            .put(TypeName.FLOAT, FloatCoder.of())
            .put(TypeName.DOUBLE, DoubleCoder.of())
            .put(TypeName.STRING, StringUtf8Coder.of())
            .put(TypeName.DATETIME, InstantCoder.of())
            .put(TypeName.BOOLEAN, BooleanCoder.of())
            .build();
  
    private static class LogicalTypeCoder<InputT, BaseT> extends Coder<InputT> {
      private final LogicalType<InputT, BaseT> logicalType;
      private final Coder<BaseT> baseTypeCoder;
      private final boolean isDateTime;
  
      LogicalTypeCoder(LogicalType<InputT, BaseT> logicalType, Coder baseTypeCoder) {
        this.logicalType = logicalType;
        this.baseTypeCoder = baseTypeCoder;
        this.isDateTime = logicalType.getBaseType().equals(FieldType.DATETIME);
      }
  
      @Override
      public void encode(InputT value, OutputStream outStream) throws CoderException, IOException {
        BaseT baseType = logicalType.toBaseType(value);
        if (isDateTime) {
          baseType = (BaseT) ((ReadableInstant) baseType).toInstant();
        }
        baseTypeCoder.encode(baseType, outStream);
      }
  
      @Override
      public InputT decode(InputStream inStream) throws CoderException, IOException {
        BaseT baseType = baseTypeCoder.decode(inStream);
        return logicalType.toInputType(baseType);
      }
  
      @Override
      public List<? extends Coder<?>> getCoderArguments() {
        return Collections.emptyList();
      }
  
      @Override
      public void verifyDeterministic() throws NonDeterministicException {
        baseTypeCoder.verifyDeterministic();
      }
  
      @Override
      public boolean consistentWithEquals() {
        // we can't assume that InputT is consistent with equals.
        // TODO: We should plumb this through to logical types.
        return false;
      }
  
      @Override
      public Object structuralValue(InputT value) {
        if (baseTypeCoder.consistentWithEquals()) {
          return logicalType.toBaseType(value);
        } else {
          return baseTypeCoder.structuralValue(logicalType.toBaseType(value));
        }
      }
  
      @Override
      public boolean isRegisterByteSizeObserverCheap(InputT value) {
        return baseTypeCoder.isRegisterByteSizeObserverCheap(logicalType.toBaseType(value));
      }
  
      @Override
      public void registerByteSizeObserver(InputT value, ElementByteSizeObserver observer)
          throws Exception {
        baseTypeCoder.registerByteSizeObserver(logicalType.toBaseType(value), observer);
      }
    }
  
    /** Returns the coder used for a given primitive type. */
    public static <T> Coder<T> coderForFieldType(FieldType fieldType) {
      Coder<T> coder;
      switch (fieldType.getTypeName()) {
        case ROW:
          coder = (Coder<T>) SchemaCoder.of(fieldType.getRowSchema());
          break;
        case ARRAY:
          coder = (Coder<T>) ListCoder.of(coderForFieldType(fieldType.getCollectionElementType()));
          break;
        case ITERABLE:
          coder =
              (Coder<T>) IterableCoder.of(coderForFieldType(fieldType.getCollectionElementType()));
          break;
        case MAP:
          coder =
              (Coder<T>)
                  MapCoder.of(
                      coderForFieldType(fieldType.getMapKeyType()),
                      coderForFieldType(fieldType.getMapValueType()));
          break;
        case LOGICAL_TYPE:
          coder =
              new LogicalTypeCoder(
                  fieldType.getLogicalType(),
                  coderForFieldType(fieldType.getLogicalType().getBaseType()));
          break;
        default:
          coder = (Coder<T>) CODER_MAP.get(fieldType.getTypeName());
      }
      Preconditions.checkNotNull(coder, "Unexpected field type %s", fieldType.getTypeName());
      if (fieldType.getNullable()) {
        coder = NullableCoder.of(coder);
      }
      return coder;
    }
  }
  