gudzii-ov/php-project-lvl1

<?php

namespace BrainGames\games\progression;

use function BrainGames\engine\runEngine;

const MESSAGE = 'What number is missing in the progression?';
const PROGRESSION_LENGTH = 10;

function generateProgression($firstItem, $step, $length)
{
    $progression = array($firstItem);

    for ($i = 1; $i < $length; $i++) {
        $progression[$i] = $firstItem + $step * $i;
    };

    return $progression;
}

function prepareQuestion($progression, $hiddenItem)
{
    $questionData = array_map(function ($item) use ($hiddenItem) {
        return $item === $hiddenItem ? ".." : $item;
    }, $progression);

    return implode(" ", $questionData);
}

function runProgression()
{
    $getGameData = function () {
        $progressionStart = rand(0, 10);
        $progressionStep = rand(0, 9);
        $progression = generateProgression($progressionStart, $progressionStep, PROGRESSION_LENGTH);
        $hiddenItemIndex = rand(0, PROGRESSION_LENGTH - 1);

        $rightAnswer = $progression[$hiddenItemIndex];
        $question = prepareQuestion($progression, $rightAnswer);
        
        $gameData = [$question, (string) $rightAnswer];
        
        return $gameData;
    };

    runEngine(MESSAGE, $getGameData);
}