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.cassandra.cql3.functions;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.apache.cassandra.cql3.CQL3Type;
  
  import org.apache.cassandra.cql3.QueryOptions;
  import org.apache.cassandra.db.marshal.*;
  import org.apache.cassandra.exceptions.FunctionExecutionException;
  import org.apache.cassandra.exceptions.InvalidRequestException;
  import org.apache.cassandra.serializers.MarshalException;
  import org.apache.cassandra.utils.JsonUtils;
  
  import static java.lang.String.format;
  
  public class FromJsonFct extends NativeScalarFunction
  {
      private static final Map<AbstractType<?>, FromJsonFct> instances = new ConcurrentHashMap<>();
  
      public static FromJsonFct getInstance(FunctionName name, AbstractType<?> returnType)
      {
          FromJsonFct func = instances.get(returnType);
          if (func == null)
          {
              func = new FromJsonFct(name, returnType);
              instances.put(returnType, func);
          }
          return func;
      }
  
      private FromJsonFct(FunctionName name, AbstractType<?> returnType)
      {
          super(name.name, returnType, UTF8Type.instance);
      }
  
      @Override
      public ByteBuffer execute(Arguments arguments)
      {
          assert arguments.size() == 1 : format("Unexpectedly got %d arguments for %s()", arguments.size(), name.name);
  
          if (arguments.containsNulls())
              return null;
  
          String jsonArg = arguments.get(0);
          try
          {
              Object object = JsonUtils.JSON_OBJECT_MAPPER.readValue(jsonArg, Object.class);
              if (object == null)
                  return null;
  
              return returnType.fromJSONObject(object)
                               .bindAndGet(QueryOptions.forProtocolVersion(arguments.getProtocolVersion()));
          }
          catch (IOException exc)
          {
              throw FunctionExecutionException.create(name(), 
                                                      Collections.singletonList("text"),
                                                      format("Could not decode JSON string '%s': %s", jsonArg, exc));
          }
          catch (MarshalException exc)
          {
              throw FunctionExecutionException.create(this, exc);
          }
      }
  
      public static void addFunctionsTo(NativeFunctions functions)
      {
          functions.add(new Factory("from_json"));
          functions.add(new Factory("fromjson"));
      }
      
      private static class Factory extends FunctionFactory
      {
          private Factory(String name)
          {
              super(name, FunctionParameter.fixed(CQL3Type.Native.TEXT));
          }
  
          @Override
          protected NativeFunction doGetOrCreateFunction(List<AbstractType<?>> argTypes, AbstractType<?> receiverType)
          {
              if (receiverType == null)
                  throw new InvalidRequestException(format("%s() cannot be used in the selection clause of a SELECT statement", name.name));
  
              return FromJsonFct.getInstance(name, receiverType);
          }
      }
  }
  