<?php

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 * Description of Math_word_Problems
 *
 * @author gregory
 */
class math_word_problems {
   
    public $state = "error";
    private $debug = false;
    private $sql;
    private $user;
    private $difficultyValue;
    private $returnData;

    /**
     * Setup new numbers engine
     * 
     * @param bool $test Enable debug mode.
     */
    public function __construct($test = false) {
       
        if ($test) {
            $this->debug = true;
        }
        $this->sql = e107::getDB();
        $this->user = e107::getUser()->getLoginName();
        $this->state = "ready";
    }

    public function getProblem() {

        $this->difficultyValue = $this->difficulty();
        
        if($this->debug) {
            $this->returnData['difficulty'] = $this->difficultyValue;            
        }
        
        $this->questionAssembler();
        
        return $this->returnData;
    }
    
    private function questionAssembler() { //return [ 'answer1'=>$solution['/'], 'question'=>$TempQuestion, 'type'=>__CLASS__];
        
        $questionIndexSelected = array_rand($this->questionData());
        $question = $this->questionData()[$questionIndexSelected];
        $this->returnData['question'] = $this->substitutor($question);
        //print_a([__CLASS__.' '.__FUNCTION__=>['rawQuestion'=>$question,'processedQuestion'=>$this->returnData['question']]]);
    }
    
    private function questionData() { 
        $wordedMath = [
            ['{name1} used {int,1,1,diff} meters of cloth to sew {int,2,1,diff} pillow cases. How much cloth would be used to sew {int,3,2,diff} pillow cases?','(({int,1,1,diff}/{int,2,1,diff})*{int,3,2,diff})'],
            //['A mother makes {int,1,1,diff} sandwiches for a party. Each child received {int,2,1,diff} sandwiches. How many children were at the party?','({int,1,1,diff}/{int,2,1,diff})'],
            ['The mass of a sponge is {int,1,1,diff} g. When put in water it expanded and gained a mass of {int,2,1,diff} g. Find the mass difference if {int,3,1,diff} similar sponges were used in the experiment?','({int,2,1,diff}*{int,3,1,diff})'],
            //['{name1} is {int,1,1,diff} years old. His brother is {int,2,1,diff} months older than him. How old is {name1}’s brother?','({int,1,1,diff}+({int,1,1,diff}/12))'],
            ['An elephant eats {int,1,1,diff} kg of food a week. How much will it eat in {int,2,1,10} years?','(({int,1,1,diff}*52)*{int,2,1,10})'],
//            ['A cake recipe uses 60 g of flour. How many cakes can I bake with 4.2 kg of flour?'],
//            ['On a scale there is 88 grams on side A and 1.3 kg on side B. How much more weight do I need to put on side A to balance the scale?','()'],
//            ['{name1} baked 400 cupcakes and she sold 2 fifths at the market. How many cupcakes does she have left?'],
//            ['A baker baked 720 slices of pizza. He sold 5 nineths of the pizzas and threw away 45 slices. How many slices were left?'],
//            ['A cake recipe uses 1 quarter kilogram of sugar. How many cakes can I bake with 750 grams of sugar?'],
//            ['There were 280 marbles in a jar. {name1} dropped the jar and lost 3 quarters of the marbles. How many marbles were left?'],
//            ['At the beach there were 675 people. One fifth were children and the rest were adults. How many adults were at the beach?'],
//            ['{name1} is 56 years old and has a brother who is 84 months younger. How old is his brother?'],
//            ['{name1} has to pack 28.35 kg of sugar into 10 bags equally. How much sugar would each bag contain?'],
//            ['There was 310.4 kg of sand. It has to be divided into 100 tubs equally. How much sand would each tub contain?'],
//            ['A packet contains 2.39 kg of flour. {name1} bought 1000 packets for her cake shop. How much flour does she have in total?'],
        ];
        return $wordedMath;
    }

    /**
     * Return the difficulty based on previously answered questions.
     *
     * @return int Difficulty as percent.
     */
    private function difficulty() {

        $query = "SELECT (SUM(correct)/COUNT(correct)*100) as percent
            FROM e107.`e107_tkReport` WHERE 
            answereddatestamp >= unix_timestamp((NOW()) - INTERVAL 1 MONTH)
            AND username = '$this->user' AND subject = '".__CLASS__."';";

        if($this->debug) {
            $this->returnData['difficultySQL'] = $query;
        }
        
        $this->sql->gen($query);
        while ($row = $this->sql->fetch()) {
            if (is_numeric($row["percent"])) {
                return (int)$row["percent"];
            } else {
                return 1;
            }
        }
     
    }
    
    private function substitutor($question) {
        
        $questionStr = $this->names($question[0]);
        $solutionStr = $this->names($question[1]);
        
        $questionArray = preg_split("/{|}/",$questionStr);
        
        foreach ($questionArray as $questionPart) {
            if($this->contains('int', $questionPart)) {
                $substituteString = $this->ints(explode(',',$questionPart));
                $questionStr = str_replace('{'.$questionPart.'}', $substituteString, $questionStr);
                $solutionStr = str_replace('{'.$questionPart.'}', $substituteString, $solutionStr);
            }
            
        }
        // eval needed
        return [ 'answer1'=>(int)eval("return ".$solutionStr.";"), 'question'=>$questionStr, 'type'=>__CLASS__];
    }
    
    private function names($questionString) { 
        
        $freeNames = ['Anna','George','Marie','Elliot','Paul','Stacey','Maureen'];
        
        for ($int = 1; $int <= 10; $int++) {
            $randomName = array_rand($freeNames);
            
            if($this->contains('{name'.$int.'}', $questionString)) {
                $name = $freeNames[$randomName];
                
                $questionString = str_replace('{name'.$int.'}', $name, $questionString);
                unset($freeNames[$randomName]);
            }else{
                break;
            }
        } 
        return $questionString;
    }

    
    private function ints($dataBlock) {
        foreach ($dataBlock as $key=>&$data) {
            if($this->contains('diff', $data)) {
                $data = (int)$this->difficultyValue;
                if($data<$dataBlock[($key-1)]) {
                    $data = $dataBlock[($key-1)];
                }
            }
                            
        }
        
        return mt_rand($dataBlock[2],$dataBlock[3]);
    }
    
    /**
     * contains($needle, $haystack)
     * 
     * <code>
     * Example;<br/>
     * $haystack = 'Hello how are you';<br/>
     * $needle = 'are';<br/>
     * contains($needle, $haystack); // == true<br/>
     * </code>
     * @param string $needle
     * @param string $haystack
     * @return bool
     */
    function contains($needle, $haystack)
    {
        return strpos($haystack, $needle) !== false;
    }
    
}