<?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.
 */

/**
 * This class contains the code for checking the user supplied answers
 * @author Gregory Huxley <pigs.fly.in.packs@gmail.com>
 */
class AnswerChecker {
    
    private $questionString;
    private $correct;
    private $userName;
    private $sql;
    
    public function __construct() {
        $this->userName = e107::getUser()->getLoginName();
        $this->sql = e107::getDb();
    }
    
    public function checkAnswers() {
        
        //print_a('deleting session val.');
            setcookie('tkQuestion', '', time()-7200);
        
        $decodedQuestion = json_decode(base64_decode(filter_input(INPUT_POST, 'checkerData')),true);
        //print_a([$_POST, $decodedQuestion]);  
        $int = 1;
        while (filter_input(INPUT_POST, 'a'.$int)) {
            $decodedQuestion['userAnswer'.$int] = filter_input(INPUT_POST, 'a'.$int);
            $int++;
        }
        
        if(isset($decodedQuestion['answer1'])) {
            $this->questionFormater($decodedQuestion);
            if ($this->cheating($decodedQuestion['question'])) {
                return 't'; //silently fail
            }
            
            $anserString = $this->checkAnswer($decodedQuestion);
            //print_a(['anserString'=>$anserString]);
            if($this->correct) {
                $text .= "Congratulations '" . trim(trim($anserString['user']),',') . "' was correct for " . $this->questionString . "<br/>";
            }else{
                $text .= "Sorry but '" . trim(trim($anserString['user']),',') . "' was incorrect it should have been '" . trim(trim($anserString['correct']),',') . "' for " . $this->questionString . "<br/>";
            }
            
            $this->addToReport($anserString,$decodedQuestion);
            $this->addRewardPoint();
            //print_a(['rawPost'=>$_POST, 'decodedPost'=>$decodedQuestion,'questionString'=>$this->questionString]);    
            return $text;
        }
        
    }

    
    private function cheating() {

        $lastQuestion = $this->sql->retrieve('tkReport', 'question', 'username="' . $this->userName . '" ORDER BY id DESC LIMIT 1');
        
        if ($lastQuestion == $this->questionString) {
            return true;
        }
        return false;
    }
    
    
    private function checkAnswer($decodedQuestion) {

        $this->correct = true;
        $answers = ['correct'=>'','user'=>''];
        $int = 1;
        
        while (isset($decodedQuestion['userAnswer'.$int])) {
            if($decodedQuestion['userAnswer'.$int] == $decodedQuestion['answer'.$int]) {
                // true
            }else{
                $this->correct = false;
            }
            $answers['correct'] .= $decodedQuestion['answer'.$int] . ', ';
            $answers['user'] .= $decodedQuestion['userAnswer'.$int] . ', ';
            $int++;
        }
        return $answers;
    }
    
    
    private function questionFormater($data) {
        
        switch ($data['type']) {
                case 'numbers':
                    $this->numbers($data['question']);
                    break;
                case 'spelling':
                    $this->spelling($data['answer1']);
                    break;
                case 'numeracy':
                    $this->numeracy($data['question']);
                    break;
                case 'math_word_problems':
                    $this->math_word_problems($data['question']);
                    break;
                case 'elements':
                    $this->elements($data['question']);
                    break;

                default:
                    $this->questionString = 'format error.';
                    print_a([$data['type'] => $data]);
                    break;
            }
    }
    
    
    private function elements($data) {
        //print_a($data);
                if($data[1]=='name'){
        $this->questionString = 'Find the missing information for element '.$data['element']['symbol'].'?';
                }else{
        $this->questionString = 'Find the missing information for element '.$data['element']['name'].'?';            
                }
    }
    
    private function spelling($data) {
        $this->questionString = 'Spell the word \'' . $data . '\'.';
    }
    
    private function numeracy($data) {
        
        if($data[1]=='r') {
            $this->questionString = 'Round the following off to the nearest 5 cents. ' . $data[0];
        }else{
            $this->questionString = $data[0] . ' ' . $data[1] . ' ' . $data[2] . ' =';
        }
    }
    
    private function math_word_problems($data) {
        
            $this->questionString = $data;
    }
    
     private function numbers($data) {
        
        $retString = '';
        foreach($data as $seq) {
            $retString .= $seq;
        }
        
        $this->questionString = 'Find the missing number? '.trim($retString,',');
    }
    
    private function addToReport($answers,$data) {
       
        if($this->correct) {
            $correct = 1;
        }else{
            $correct = 0;
        }
        
        $insert = [
            'username' => $this->userName,
            'question' => $this->questionString,
            'answereddatestamp' => time(),
            'userAnswer' => trim(trim($answers['user']),','),
            'answer' => trim(trim($answers['correct']),','),
            'subject' => $data['type'],
            'correct' => $correct
        ];
        //print_a(['SQLinsert'=>$insert]);
        $this->sql->insert('tkReport', $insert);
    }
    
    private function addRewardPoint() {
        // TODO link to minecraft/minetest engines
    }
    
}