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.asterix.runtime.evaluators.functions;
  
  import java.io.DataOutput;
  import java.io.IOException;
  
  import org.apache.asterix.common.annotations.MissingNullInOutFunction;
  import org.apache.asterix.dataflow.data.nontagged.serde.AFloatSerializerDeserializer;
  import org.apache.asterix.formats.nontagged.SerializerDeserializerProvider;
  import org.apache.asterix.fuzzyjoin.similarity.SimilarityFiltersJaccard;
  import org.apache.asterix.om.base.AInt32;
  import org.apache.asterix.om.base.AMutableInt32;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.functions.IFunctionDescriptorFactory;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.hierachy.ATypeHierarchy;
  import org.apache.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
  import org.apache.asterix.runtime.exceptions.TypeMismatchException;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluator;
  import org.apache.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
  import org.apache.hyracks.api.context.IEvaluatorContext;
  import org.apache.hyracks.api.dataflow.value.ISerializerDeserializer;
  import org.apache.hyracks.api.exceptions.HyracksDataException;
  import org.apache.hyracks.data.std.api.IPointable;
  import org.apache.hyracks.data.std.primitive.VoidPointable;
  import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
  import org.apache.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
  
  @MissingNullInOutFunction
  public class PrefixLenJaccardDescriptor extends AbstractScalarFunctionDynamicDescriptor {
  
      private static final long serialVersionUID = 1L;
      public static final IFunctionDescriptorFactory FACTORY = PrefixLenJaccardDescriptor::new;
  
      @Override
      public IScalarEvaluatorFactory createEvaluatorFactory(final IScalarEvaluatorFactory[] args) {
          return new IScalarEvaluatorFactory() {
              private static final long serialVersionUID = 1L;
  
              @Override
              public IScalarEvaluator createScalarEvaluator(final IEvaluatorContext ctx) throws HyracksDataException {
  
                  return new IScalarEvaluator() {
  
                      private final ArrayBackedValueStorage resultStorage = new ArrayBackedValueStorage();
                      private final DataOutput out = resultStorage.getDataOutput();
                      private final IPointable lenPtr = new VoidPointable();
                      private final IPointable thresholdPtr = new VoidPointable();
                      private final IScalarEvaluator evalLen = args[0].createScalarEvaluator(ctx);
                      private final IScalarEvaluator evalThreshold = args[1].createScalarEvaluator(ctx);
  
                      private float similarityThresholdCache;
                      private SimilarityFiltersJaccard similarityFilters;
  
                      // result
                      private final AMutableInt32 res = new AMutableInt32(0);
                      @SuppressWarnings("unchecked")
                      private final ISerializerDeserializer<AInt32> int32Serde =
                              SerializerDeserializerProvider.INSTANCE.getSerializerDeserializer(BuiltinType.AINT32);
  
                      @Override
                      public void evaluate(IFrameTupleReference tuple, IPointable result) throws HyracksDataException {
                          resultStorage.reset();
                          evalLen.evaluate(tuple, lenPtr);
                          evalThreshold.evaluate(tuple, thresholdPtr);
  
                          if (PointableHelper.checkAndSetMissingOrNull(result, lenPtr, thresholdPtr)) {
                              return;
                          }
  
                          // length
                          int length = ATypeHierarchy.getIntegerValue(getIdentifier().getName(), 0, lenPtr.getByteArray(),
                                  lenPtr.getStartOffset());
                          // similarity threshold
                          byte[] data = thresholdPtr.getByteArray();
                          int offset = thresholdPtr.getStartOffset();
                          if (data[offset] != ATypeTag.SERIALIZED_FLOAT_TYPE_TAG) {
                              throw new TypeMismatchException(sourceLoc, getIdentifier(), 1, data[offset],
                                      ATypeTag.SERIALIZED_FLOAT_TYPE_TAG);
                          }
                          float similarityThreshold = AFloatSerializerDeserializer.getFloat(data, offset + 1);
  
                          if (similarityThreshold != similarityThresholdCache || similarityFilters == null) {
                              similarityFilters = new SimilarityFiltersJaccard(similarityThreshold);
                          }
  
                          int prefixLength = similarityFilters.getPrefixLength(length);
                          res.setValue(prefixLength);
  
                          try {
                              int32Serde.serialize(res, out);
                          } catch (IOException e) {
                              throw HyracksDataException.create(e);
                          }
                          result.set(resultStorage);
                      }
                  };
              }
          };
      }
  
      @Override
      public FunctionIdentifier getIdentifier() {
          return BuiltinFunctions.PREFIX_LEN_JACCARD;
      }
  
  }
  