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package org.apache.poi.ss.formula.functions;

import org.apache.poi.ss.formula.eval.AreaEval;
import org.apache.poi.ss.formula.eval.ErrorEval;
import org.apache.poi.ss.formula.eval.EvaluationException;
import org.apache.poi.ss.formula.eval.NumberEval;
import org.apache.poi.ss.formula.eval.RefEval;
import org.apache.poi.ss.formula.eval.ValueEval;
import org.apache.poi.ss.formula.functions.CountUtils.I_MatchPredicate;

Implementation for the Excel function SUMIF

Syntax : 

 SUMIF ( range, criteria, sum_range ) 

   

     
range
The range over which criteria is applied.  Also used for addend values when the third parameter is not present
     
criteria
The value or expression used to filter rows from range
     
sum_range
Locates the top-left corner of the corresponding range of addends - values to be added (after being selected by the criteria)
   



Author:
Josh Micich/**
 * Implementation for the Excel function SUMIF<p>
 *
 * Syntax : <br>
 *  SUMIF ( <b>range</b>, <b>criteria</b>, sum_range ) <br>
 *    <table border="0" cellpadding="1" cellspacing="0" summary="Parameter descriptions">
 *      <tr><th>range</th><td>The range over which criteria is applied.  Also used for addend values when the third parameter is not present</td></tr>
 *      <tr><th>criteria</th><td>The value or expression used to filter rows from <b>range</b></td></tr>
 *      <tr><th>sum_range</th><td>Locates the top-left corner of the corresponding range of addends - values to be added (after being selected by the criteria)</td></tr>
 *    </table><br>
 * </p>
 * @author Josh Micich
 */
public final class Sumif extends Var2or3ArgFunction {

	public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0, ValueEval arg1) {

		AreaEval aeRange;
		try {
			aeRange = convertRangeArg(arg0);
		} catch (EvaluationException e) {
			return e.getErrorEval();
		}
		return eval(srcRowIndex, srcColumnIndex, arg1, aeRange, aeRange);
	}

	public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg0, ValueEval arg1,
			ValueEval arg2) {

		AreaEval aeRange;
		AreaEval aeSum;
		try {
			aeRange = convertRangeArg(arg0);
			aeSum = createSumRange(arg2, aeRange);
		} catch (EvaluationException e) {
			return e.getErrorEval();
		}
		return eval(srcRowIndex, srcColumnIndex, arg1, aeRange, aeSum);
	}

	private static ValueEval eval(int srcRowIndex, int srcColumnIndex, ValueEval arg1, AreaEval aeRange,
			AreaEval aeSum) {
		// TODO - junit to prove last arg must be srcColumnIndex and not srcRowIndex
		I_MatchPredicate mp = Countif.createCriteriaPredicate(arg1, srcRowIndex, srcColumnIndex);
		
		// handle empty cells
		if(mp == null) {
		    return NumberEval.ZERO;
		}

		double result = sumMatchingCells(aeRange, mp, aeSum);
		return new NumberEval(result);
	}

	private static double sumMatchingCells(AreaEval aeRange, I_MatchPredicate mp, AreaEval aeSum) {
		int height=aeRange.getHeight();
		int width= aeRange.getWidth();

		double result = 0.0;
		for (int r=0; r<height; r++) {
			for (int c=0; c<width; c++) {
				result += accumulate(aeRange, mp, aeSum, r, c);
			}
		}
		return result;
	}

	private static double accumulate(AreaEval aeRange, I_MatchPredicate mp, AreaEval aeSum, int relRowIndex,
			int relColIndex) {

		if (!mp.matches(aeRange.getRelativeValue(relRowIndex, relColIndex))) {
			return 0.0;
		}
		ValueEval addend = aeSum.getRelativeValue(relRowIndex, relColIndex);
		if (addend instanceof NumberEval) {
			return ((NumberEval)addend).getNumberValue();
		}
		// everything else (including string and boolean values) counts as zero
		return 0.0;
	}

	
Throws:
EvaluationException – if eval is not a reference
Returns:
a range of the same dimensions as aeRange using eval to define the top left corner./**
	 * @return a range of the same dimensions as aeRange using eval to define the top left corner.
	 * @throws EvaluationException if eval is not a reference
	 */
	private static AreaEval createSumRange(ValueEval eval, AreaEval aeRange) throws EvaluationException {
		if (eval instanceof AreaEval) {
			return ((AreaEval) eval).offset(0, aeRange.getHeight()-1, 0, aeRange.getWidth()-1);
		}
		if (eval instanceof RefEval) {
			return ((RefEval)eval).offset(0, aeRange.getHeight()-1, 0, aeRange.getWidth()-1);
		}
		throw new EvaluationException(ErrorEval.VALUE_INVALID);
	}

	private static AreaEval convertRangeArg(ValueEval eval) throws EvaluationException {
		if (eval instanceof AreaEval) {
			return (AreaEval) eval;
		}
		if (eval instanceof RefEval) {
			return ((RefEval)eval).offset(0, 0, 0, 0);
		}
		throw new EvaluationException(ErrorEval.VALUE_INVALID);
	}

}