<?php

require_once "PicturedTask.php";

class SingleChoiceTask extends PicturedTask
{
    private array $answers; // possible answers

    // -----------------

    function __construct(array $a = null)
    {
        parent::__construct("singlechoice", $a);

        $this->answers = $a["answers"] ?? [];
        $ca  = $a["correct_answer"] ?? -1;
        if (gettype($ca) === "string") { // backward compatibility
            $this->correct_answer = array_search($a["correct_answer"], $this->answers);
        } else {
            $this->correct_answer = (int)($ca);
        }
        $this->player_answer = $a["player_answer"] ?? -1;
    }

    function addAnswer(string $answer): void
    {
        $this->answers[] = $answer;
    }

    function clearAnswers(): void {
        $this->answers = [];
    }

    function getAnswers(): array
    {
        return $this->answers;
    }

    private function isAnswerIdInsideBounds(int $ansid): bool
    {
        return ($ansid >= 0) && ($ansid <= count($this->answers));
    }

    function saveAnswer(mixed $ans): bool
    {
        $ansidx = (int)($ans); // cast answer to integer as it is a number
        if ($this->isAnswerIdInsideBounds($ansidx)) {
            $this->player_answer = $ansidx;
            return true;
        }

        return false;
    }

    function clearAnswer(): void
    {
        $this->player_answer = -1;
    }

    function staticCheck(): void
    {
        $mark = ($this->player_answer == $this->correct_answer) ? $this->getMaxMark() : 0.0;
        $this->setMark($mark);
    }

    function toArray(string $mode = "all"): array
    {
        $a = parent::toArray($mode);
        $a["answers"] = $this->answers;
        $a["correct_answer"] = $this->correct_answer;
        return $a;
    }

    function randomize(): void{
        parent::randomize();

        $ordering = range(0, count($this->answers) - 1); // create an ordered range
        shuffle($ordering); // shuffle indices
        $shans = [];
        $ca_remapped = false; // avoid remapping the correct answer multiple times
        for ($i = 0; $i < count($this->answers); $i++) { // shuffle answers
            $orig_pos = $ordering[$i];
            $shans[] = $this->answers[$orig_pos];
            if ((!$ca_remapped) && ($orig_pos == $this->correct_answer)) {
                $this->correct_answer = $i;
                $ca_remapped = true;
            }

        }
        $this->answers = $shans;
    }
}