phoenix-core/src/main/java/org/apache/phoenix/expression/function/FloorDateExpression.java

/*
 * 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.phoenix.expression.function;

import java.sql.Date;
import java.sql.SQLException;
import java.util.List;

import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.CoerceExpression;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.LiteralExpression;
import org.apache.phoenix.parse.FunctionParseNode.Argument;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.parse.FunctionParseNode.FunctionClassType;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PDate;
import org.apache.phoenix.schema.types.PInteger;
import org.apache.phoenix.schema.types.PTimestamp;
import org.apache.phoenix.schema.types.PUnsignedDate;
import org.apache.phoenix.schema.types.PUnsignedTimestamp;
import org.apache.phoenix.schema.types.PVarchar;

import com.google.common.collect.Lists;

/**
 * 
 * Class encapsulating the FLOOR operation on 
 * a column/literal of type {@link org.apache.phoenix.schema.types.PDate}.
 *
 * 
 * @since 3.0.0
 */
@BuiltInFunction(name = FloorFunction.NAME,
         args = {
                 @Argument(allowedTypes={PTimestamp.class}),
                 @Argument(allowedTypes={PVarchar.class, PInteger.class}, defaultValue = "null", isConstant=true),
                 @Argument(allowedTypes={PInteger.class}, defaultValue="1", isConstant=true)
         },
         classType = FunctionClassType.DERIVED
        )
public class FloorDateExpression extends RoundDateExpression {
    
    public FloorDateExpression() {}
    
    public FloorDateExpression(List<Expression> children) {
        super(children);
    }
    
    public static Expression create(List<Expression> children) throws SQLException {
        Expression firstChild = children.get(0);
        PDataType firstChildDataType = firstChild.getDataType();
        if (firstChildDataType == PTimestamp.INSTANCE || firstChildDataType == PUnsignedTimestamp.INSTANCE){
            // Coerce TIMESTAMP to DATE, as the nanos has no affect
            List<Expression> newChildren = Lists.newArrayListWithExpectedSize(children.size());
            newChildren.add(CoerceExpression.create(firstChild, firstChildDataType == PTimestamp.INSTANCE ? PDate.INSTANCE : PUnsignedDate.INSTANCE));
            newChildren.addAll(children.subList(1, children.size()));
            children = newChildren;
        }
       
        Object timeUnitValue = ((LiteralExpression)children.get(1)).getValue();
        TimeUnit timeUnit = TimeUnit.getTimeUnit(timeUnitValue != null ? timeUnitValue.toString() : null);
        switch(timeUnit) {
        case WEEK:
             return new FloorWeekExpression(children);
        case MONTH:
             return new FloorMonthExpression(children);
        case YEAR:
             return new FloorYearExpression(children);
         default:
             return new FloorDateExpression(children);
        }
        
    }
    
    /**
     * @param timeUnit - unit of time to round up to.
     * Creates a {@link FloorDateExpression} with default multiplier of 1.
     */
    public static Expression create(Expression expr, TimeUnit timeUnit) throws SQLException {
        return create(expr, timeUnit, 1);
    }
    
    /**
     * @param timeUnit - unit of time to round up to
     * @param multiplier - determines the roll up window size.
     * Create a {@link FloorDateExpression}. 
     */
    public static Expression create(Expression expr, TimeUnit timeUnit, int multiplier) throws SQLException {
        Expression timeUnitExpr = getTimeUnitExpr(timeUnit);
        Expression defaultMultiplierExpr = getMultiplierExpr(multiplier);
        List<Expression> expressions = Lists.newArrayList(expr, timeUnitExpr, defaultMultiplierExpr);
        return create(expressions);
    }
   
    @Override
    protected long getRoundUpAmount() {
        return 0;
    }
    
    @Override
    public String getName() {
        return FloorFunction.NAME;
    }
    
    @Override
    public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
        if (children.get(0).evaluate(tuple, ptr)) {
            if (ptr.getLength()==0) {
                return true;
            }
            PDataType dataType = getDataType();
            long time = dataType.getCodec().decodeLong(ptr, children.get(0).getSortOrder());
            long value = roundTime(time);
            Date d = new Date(value);
            byte[] byteValue = dataType.toBytes(d);
            ptr.set(byteValue);
            return true;
        }
        return false;
    }
}