<?php

namespace App\Http\Requests\Traits;

use Illuminate\Support\Facades\Session;

/**
 * Simple arithmetic CAPTCHA implemented with pure Laravel primitives.
 *
 * Generates a sum of two random integers, stores the expected result in
 * the session and validates the user answer. It introduces no external
 * dependency and is therefore safe from third-party licensing concerns.
 */
trait ValidatesMathCaptcha
{
    /**
     * Generate a new math challenge and persist it in the session.
     *
     * @return array{a: int, b: int, question: string}
     */
    protected static function generateMathCaptcha(): array
    {
        $a = random_int(1, 9);
        $b = random_int(1, 9);

        Session::put('captcha_result', $a + $b);
        // Sliding expiry: challenge is valid for 10 minutes.
        Session::put('captcha_expires_at', now()->addMinutes(10)->getTimestamp());

        return [
            'a' => $a,
            'b' => $b,
            'question' => sprintf('%d + %d = ?', $a, $b),
        ];
    }

    /**
     * Validate the submitted CAPTCHA answer against the session value.
     */
    protected function validateMathCaptcha(): bool
    {
        $expected = Session::get('captcha_result');
        $expiresAt = Session::get('captcha_expires_at');

        // Invalidate the challenge after it is consumed.
        Session::forget(['captcha_result', 'captcha_expires_at']);

        if ($expected === null || $expiresAt === null) {
            return false;
        }

        if (now()->getTimestamp() > (int) $expiresAt) {
            return false;
        }

        return (int) $this->input('captcha') === (int) $expected;
    }
}