asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/functions/temporal/DateFromDatetimeDescriptor.java

package edu.uci.ics.asterix.runtime.evaluators.functions.temporal;

import java.io.DataOutput;

import edu.uci.ics.asterix.common.functions.FunctionConstants;
import edu.uci.ics.asterix.dataflow.data.nontagged.serde.ADateTimeSerializerDeserializer;
import edu.uci.ics.asterix.formats.nontagged.AqlSerializerDeserializerProvider;
import edu.uci.ics.asterix.om.base.ADate;
import edu.uci.ics.asterix.om.base.AMutableDate;
import edu.uci.ics.asterix.om.base.ANull;
import edu.uci.ics.asterix.om.base.temporal.GregorianCalendarSystem;
import edu.uci.ics.asterix.om.functions.IFunctionDescriptor;
import edu.uci.ics.asterix.om.functions.IFunctionDescriptorFactory;
import edu.uci.ics.asterix.om.types.ATypeTag;
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.data.std.util.ArrayBackedValueStorage;
import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference;

public class DateFromDatetimeDescriptor extends AbstractScalarFunctionDynamicDescriptor {

    private static final long serialVersionUID = 1L;
    public final static FunctionIdentifier FID = new FunctionIdentifier(FunctionConstants.ASTERIX_NS,
            "date-from-datetime", 1);

    // allowed input types
    private final static byte SER_NULL_TYPE_TAG = ATypeTag.NULL.serialize();
    private final static byte SER_DATETIME_TYPE_TAG = ATypeTag.DATETIME.serialize();

    public final static IFunctionDescriptorFactory FACTORY = new IFunctionDescriptorFactory() {

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

    };

    @Override
    public ICopyEvaluatorFactory createEvaluatorFactory(final 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();
                    private ArrayBackedValueStorage argOut = new ArrayBackedValueStorage();
                    private ICopyEvaluator eval = args[0].createEvaluator(argOut);

                    // possible returning types
                    @SuppressWarnings("unchecked")
                    private ISerializerDeserializer<ADate> dateSerde = AqlSerializerDeserializerProvider.INSTANCE
                            .getSerializerDeserializer(BuiltinType.ADATE);
                    private AMutableDate aDate = new AMutableDate(0);

                    @SuppressWarnings("unchecked")
                    private ISerializerDeserializer<ANull> nullSerde = AqlSerializerDeserializerProvider.INSTANCE
                            .getSerializerDeserializer(BuiltinType.ANULL);

                    @Override
                    public void evaluate(IFrameTupleReference tuple) throws AlgebricksException {
                        argOut.reset();
                        eval.evaluate(tuple);
                        try {
                            if (argOut.getByteArray()[0] == SER_NULL_TYPE_TAG) {
                                nullSerde.serialize(ANull.NULL, out);
                            } else {
                                if (argOut.getByteArray()[0] != SER_DATETIME_TYPE_TAG) {
                                    throw new AlgebricksException(
                                            "Inapplicable input type for function date_from_datetime: expecting ADateTime ("
                                                    + SER_DATETIME_TYPE_TAG + ") or null (" + SER_NULL_TYPE_TAG
                                                    + "), but got: " + argOut.getByteArray()[0]);
                                }
                                long datetimeChronon = ADateTimeSerializerDeserializer.getChronon(
                                        argOut.getByteArray(), 1);
                                int dateChrononInDays = (int) (datetimeChronon / GregorianCalendarSystem.CHRONON_OF_DAY);
                                if (dateChrononInDays < 0
                                        && datetimeChronon % GregorianCalendarSystem.CHRONON_OF_DAY != 0) {
                                    dateChrononInDays -= 1;
                                }
                                aDate.setValue(dateChrononInDays);
                                dateSerde.serialize(aDate, out);
                            }
                        } catch (HyracksDataException hex) {
                            throw new AlgebricksException(hex);
                        }
                    }
                };
            }
        };
    }

    @Override
    public FunctionIdentifier getIdentifier() {
        return FID;
    }

}