<?php

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; under version 2
 * of the License (non-upgradable).
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (c) 2013 (original work) Open Assessment Technologies SA (under the project TAO-PRODUCT);
 *
 *
 */
namespace oat\taoQtiItem\model\qti\expression;

use oat\taoQtiItem\model\qti\expression\ExpressionParserFactory;
use oat\taoQtiItem\model\qti\expression\CommonExpression;
use \SimpleXMLElement;

/**
 * Short description of class
 *
 * @access public
 * @author Joel Bout, <joel.bout@tudor.lu>
 * @package taoQTI

 */
class ExpressionParserFactory
{
    // --- ASSOCIATIONS ---


    // --- ATTRIBUTES ---

    // --- OPERATIONS ---

    /**
     * Short description of method build
     *
     * @access public
     * @author Joel Bout, <joel.bout@tudor.lu>
     * @param  SimpleXMLElement data
     * @return oat\taoQtiItem\model\qti\expression\Expression
     */
    public static function build(SimpleXMLElement $data)
    {
        $returnValue = null;

        
        $expression = null;
        $expressionName = $data->getName();
        
        //retrieve the expression attributes
        $attributes = [];
        foreach ($data->attributes() as $key => $value) {
            $attributes[$key] = (string)$value;
        }
        
        // Create expression function of its type (If specialization has been done for the expression type)
        $expressionClass = 'oat\\taoQtiItem\\model\\qti\\expression\\' . ucfirst($expressionName);
        
        if (class_exists($expressionClass)) {
            $expression = new $expressionClass($expressionName, $attributes);
        } else {
            $expression = new CommonExpression($expressionName, $attributes);
        }
        
        // If the expression has a value
        $expressionValue = (string) trim($data);
        if ($expressionValue != '') {
            $expression->setValue($expressionValue);
        }
        
        // All sub-expressions of an expression are embedded by this expression
        $subExpressions = [];
        foreach ($data->children() as $subExpressionNode) {
            $subExpressions[] = self::build($subExpressionNode);
        }
        $expression->setSubExpressions($subExpressions);

        $returnValue = $expression;

        
        return $returnValue;
    }
}