/*
 * Copyright 2009-2013 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.
 */
/**
 * 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.hadoop.hive.ql.udf.generic;

import java.io.DataOutput;
import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.util.StringUtils;

import edu.uci.ics.hivesterix.runtime.evaluator.BufferSerDeUtil;
import edu.uci.ics.hivesterix.runtime.evaluator.SerializableBuffer;

/**
 * GenericUDAFSum.
 */
@Description(name = "sum", value = "_FUNC_(x) - Returns the sum of a set of numbers")
public class GenericUDAFSum extends AbstractGenericUDAFResolver {

    static final Log LOG = LogFactory.getLog(GenericUDAFSum.class.getName());

    @Override
    public GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters) throws SemanticException {
        if (parameters.length != 1) {
            throw new UDFArgumentTypeException(parameters.length - 1, "Exactly one argument is expected.");
        }

        if (parameters[0].getCategory() != ObjectInspector.Category.PRIMITIVE) {
            throw new UDFArgumentTypeException(0, "Only primitive type arguments are accepted but "
                    + parameters[0].getTypeName() + " is passed.");
        }
        switch (((PrimitiveTypeInfo) parameters[0]).getPrimitiveCategory()) {
            case BYTE:
            case SHORT:
            case INT:
            case LONG:
                return new GenericUDAFSumLong();
            case FLOAT:
            case DOUBLE:
            case STRING:
                return new GenericUDAFSumDouble();
            case BOOLEAN:
            default:
                throw new UDFArgumentTypeException(0, "Only numeric or string type arguments are accepted but "
                        + parameters[0].getTypeName() + " is passed.");
        }
    }

    /**
     * GenericUDAFSumDouble.
     */
    public static class GenericUDAFSumDouble extends GenericUDAFEvaluator {
        private PrimitiveObjectInspector inputOI;
        private DoubleWritable result;

        @Override
        public ObjectInspector init(Mode m, ObjectInspector[] parameters) throws HiveException {
            assert (parameters.length == 1);
            super.init(m, parameters);
            result = new DoubleWritable(0);
            inputOI = (PrimitiveObjectInspector) parameters[0];
            return PrimitiveObjectInspectorFactory.writableDoubleObjectInspector;
        }

        /** class for storing double sum value. */
        static class SumDoubleAgg implements SerializableBuffer {
            boolean empty;
            double sum;

            @Override
            public void deSerializeAggBuffer(byte[] data, int start, int len) {
                empty = BufferSerDeUtil.getBoolean(data, start);
                start += 1;
                sum = BufferSerDeUtil.getDouble(data, start);
            }

            @Override
            public void serializeAggBuffer(byte[] data, int start, int len) {
                BufferSerDeUtil.writeBoolean(empty, data, start);
                start += 1;
                BufferSerDeUtil.writeDouble(sum, data, start);
            }

            @Override
            public void serializeAggBuffer(DataOutput output) throws IOException {
                output.writeBoolean(empty);
                output.writeDouble(sum);
            }
        }

        @Override
        public AggregationBuffer getNewAggregationBuffer() throws HiveException {
            SumDoubleAgg result = new SumDoubleAgg();
            reset(result);
            return result;
        }

        @Override
        public void reset(AggregationBuffer agg) throws HiveException {
            SumDoubleAgg myagg = (SumDoubleAgg) agg;
            myagg.empty = true;
            myagg.sum = 0;
        }

        boolean warned = false;

        @Override
        public void iterate(AggregationBuffer agg, Object[] parameters) throws HiveException {
            assert (parameters.length == 1);
            try {
                merge(agg, parameters[0]);
            } catch (NumberFormatException e) {
                if (!warned) {
                    warned = true;
                    LOG.warn(getClass().getSimpleName() + " " + StringUtils.stringifyException(e));
                    LOG.warn(getClass().getSimpleName() + " ignoring similar exceptions.");
                }
            }
        }

        @Override
        public Object terminatePartial(AggregationBuffer agg) throws HiveException {
            return terminate(agg);
        }

        @Override
        public void merge(AggregationBuffer agg, Object partial) throws HiveException {
            if (partial != null) {
                SumDoubleAgg myagg = (SumDoubleAgg) agg;
                myagg.empty = false;
                myagg.sum += PrimitiveObjectInspectorUtils.getDouble(partial, inputOI);
            }
        }

        @Override
        public Object terminate(AggregationBuffer agg) throws HiveException {
            SumDoubleAgg myagg = (SumDoubleAgg) agg;
            if (myagg.empty) {
                return null;
            }
            result.set(myagg.sum);
            return result;
        }

    }

    /**
     * GenericUDAFSumLong.
     */
    public static class GenericUDAFSumLong extends GenericUDAFEvaluator {
        private PrimitiveObjectInspector inputOI;
        private LongWritable result;

        @Override
        public ObjectInspector init(Mode m, ObjectInspector[] parameters) throws HiveException {
            assert (parameters.length == 1);
            super.init(m, parameters);
            result = new LongWritable(0);
            inputOI = (PrimitiveObjectInspector) parameters[0];
            return PrimitiveObjectInspectorFactory.writableLongObjectInspector;
        }

        /** class for storing double sum value. */
        static class SumLongAgg implements SerializableBuffer {
            boolean empty;
            long sum;

            @Override
            public void deSerializeAggBuffer(byte[] data, int start, int len) {
                empty = BufferSerDeUtil.getBoolean(data, start);
                start += 1;
                sum = BufferSerDeUtil.getLong(data, start);
            }

            @Override
            public void serializeAggBuffer(byte[] data, int start, int len) {
                BufferSerDeUtil.writeBoolean(empty, data, start);
                start += 1;
                BufferSerDeUtil.writeLong(sum, data, start);
            }

            @Override
            public void serializeAggBuffer(DataOutput output) throws IOException {
                output.writeBoolean(empty);
                output.writeLong(sum);
            }
        }

        @Override
        public AggregationBuffer getNewAggregationBuffer() throws HiveException {
            SumLongAgg result = new SumLongAgg();
            reset(result);
            return result;
        }

        @Override
        public void reset(AggregationBuffer agg) throws HiveException {
            SumLongAgg myagg = (SumLongAgg) agg;
            myagg.empty = true;
            myagg.sum = 0;
        }

        private boolean warned = false;

        @Override
        public void iterate(AggregationBuffer agg, Object[] parameters) throws HiveException {
            assert (parameters.length == 1);
            try {
                merge(agg, parameters[0]);
            } catch (NumberFormatException e) {
                if (!warned) {
                    warned = true;
                    LOG.warn(getClass().getSimpleName() + " " + StringUtils.stringifyException(e));
                }
            }
        }

        @Override
        public Object terminatePartial(AggregationBuffer agg) throws HiveException {
            return terminate(agg);
        }

        @Override
        public void merge(AggregationBuffer agg, Object partial) throws HiveException {
            if (partial != null) {
                SumLongAgg myagg = (SumLongAgg) agg;
                myagg.sum += PrimitiveObjectInspectorUtils.getLong(partial, inputOI);
                myagg.empty = false;
            }
        }

        @Override
        public Object terminate(AggregationBuffer agg) throws HiveException {
            SumLongAgg myagg = (SumLongAgg) agg;
            if (myagg.empty) {
                return null;
            }
            result.set(myagg.sum);
            return result;
        }

    }

}