package org.simantics.spreadsheet.graph.formula;

import org.simantics.spreadsheet.graph.CellFormulaFunction;
import org.simantics.spreadsheet.graph.CellValueVisitor;
import org.simantics.spreadsheet.graph.SpreadsheetGraphUtils;
import org.simantics.spreadsheet.graph.parser.ast.AstArgList;
import org.simantics.spreadsheet.graph.parser.ast.AstNothing;
import org.simantics.spreadsheet.graph.parser.ast.AstValue;

public class IfFormulaFunction implements CellFormulaFunction<Object> {

    @Override
    public Object evaluate(CellValueVisitor visitor, AstArgList args) {
        if (args.values.size() != 3) throw new IllegalStateException();
        
        Object condition = args.values.get(0).accept(visitor);
        AstValue ifTrueResult = args.values.get(1);
        AstValue ifFalseResult = args.values.get(2);
        
        FormulaError2 error = FormulaError2.forObject(condition);
		if(error!=null) return error.getString();

        if (SpreadsheetGraphUtils.asBoolean(condition)) {
            if(ifTrueResult==null || ifTrueResult instanceof AstNothing)
            	return 0;
            try {
            	return ifTrueResult.accept(visitor);
            } catch (IllegalStateException e){
            	return FormulaError2.NAME.getString();
            }
        }
        else {
            if(ifFalseResult==null || ifFalseResult instanceof AstNothing)
            	return 0;
            try {
            	return ifFalseResult.accept(visitor);
            } catch (IllegalStateException e){
            	return FormulaError2.NAME.getString();
            }
        }
    }
}