/*
 * Copyright 2009-2011 by The Regents of the University of California
 * Licensed 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 from
 * 
 *     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 edu.uci.ics.asterix.runtime.evaluators.functions.temporal;

import java.io.DataOutput;

import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
import edu.uci.ics.asterix.om.base.ADateTime;
import edu.uci.ics.asterix.om.base.AMutableDateTime;
import edu.uci.ics.asterix.om.functions.AsterixBuiltinFunctions;
import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
import edu.uci.ics.asterix.om.types.BuiltinType;
import edu.uci.ics.asterix.runtime.evaluators.base.AbstractScalarFunctionDynamicDescriptor;
import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluator;
import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluatorFactory;
import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.data.std.api.IDataOutputProvider;
import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference;

public class CurrentDateTimeDescriptor extends AbstractScalarFunctionDynamicDescriptor {

    private static final long serialVersionUID = 1L;
    private final static FunctionIdentifier FID = AsterixBuiltinFunctions.CURRENT_DATETIME;

    public final static IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {

        @Override
        public IFunctionDescriptor createFunctionDescriptor() {
            return new CurrentDateTimeDescriptor();
        }
    };

    private CurrentDateTimeDescriptor() {
    }

    @Override
    public ICopyEvaluatorFactory createEvaluatorFactory(ICopyEvaluatorFactory[] args) throws AlgebricksException {
        return new ICopyEvaluatorFactory() {

            private static final long serialVersionUID = 1L;

            @Override
            public ICopyEvaluator createEvaluator(final IDataOutputProvider output) throws AlgebricksException {
                return new ICopyEvaluator() {

                    private DataOutput out = output.getDataOutput();

                    @SuppressWarnings("unchecked")
                    private ISerializerDeserializer<ADateTime> datetimeSerde = AqlSerializerDeserializerProvider.INSTANCE
                            .getSerializerDeserializer(BuiltinType.ADATETIME);
                    private AMutableDateTime aDateTime = new AMutableDateTime(0);

                    @Override
                    public void evaluate(IFrameTupleReference tuple) throws AlgebricksException {
                        try {
                            aDateTime.setValue(System.currentTimeMillis());
                            datetimeSerde.serialize(aDateTime, out);
                        } catch (HyracksDataException hex) {
                            throw new AlgebricksException(hex);
                        }
                    }
                };
            }
        };
    }

    /* (non-Javadoc)
     * @see edu.uci.ics.asterix.om.functions.IFunctionDescriptor#getIdentifier()
     */
    @Override
    public FunctionIdentifier getIdentifier() {
        return FID;
    }

}