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package com.salesforce.phoenix.expression.function;

import java.math.RoundingMode;
import java.sql.SQLException;
import java.util.List;

import com.google.common.collect.Lists;
import com.salesforce.phoenix.expression.Expression;
import com.salesforce.phoenix.expression.LiteralExpression;
import com.salesforce.phoenix.schema.PDataType;

/**
 * 
 * Class encapsulating the FLOOR operation on 
 * a column/literal of type {@link com.salesforce.phoenix.schema.PDataType#DECIMAL}.
 *
 * @author samarth.jain
 * @since 3.0.0
 */
public class FloorDecimalExpression extends RoundDecimalExpression {
    
    public FloorDecimalExpression() {}
    
    public FloorDecimalExpression(List<Expression> children) {
        super(children);
    }
    
    /**
     * Creates a {@link FloorDecimalExpression} with rounding scale given by @param scale. 
     *
     */
    public static Expression create(Expression expr, int scale) throws SQLException {
        if (expr.getDataType().isCoercibleTo(PDataType.LONG)) {
            return expr;
        }
        Expression scaleExpr = LiteralExpression.newConstant(scale, PDataType.INTEGER, true);
        List<Expression> expressions = Lists.newArrayList(expr, scaleExpr);
        return new FloorDecimalExpression(expressions);
    }
    
    /**
     * Creates a {@link FloorDecimalExpression} with a default scale of 0 used for rounding. 
     *
     */
    public static Expression create(Expression expr) throws SQLException {
        return create(expr, 0);
    }
    
    @Override
    protected RoundingMode getRoundingMode() {
        return RoundingMode.FLOOR;
    }
    
    @Override
    public String getName() {
        return FloorFunction.NAME;
    }
}
