<?php

declare(strict_types=1);

namespace App\Libraries;

/**
 * Simple self-hosted image captcha (GD), answer stored in session.
 */
class Captcha
{
    public static function issue(): string
    {
        $chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
        $code  = '';
        for ($i = 0; $i < 5; $i++) {
            $code .= $chars[random_int(0, strlen($chars) - 1)];
        }
        session()->set('captcha_code', $code);
        session()->set('captcha_expires', time() + 600);
        return $code;
    }

    public static function verify(?string $input): bool
    {
        $code = session()->get('captcha_code');
        $exp  = session()->get('captcha_expires');
        session()->remove('captcha_code');
        session()->remove('captcha_expires');

        if (! $code || ! $exp || time() > $exp || ! $input) {
            return false;
        }
        return hash_equals(strtoupper(trim($code)), strtoupper(trim($input)));
    }

    public static function render(string $code): void
    {
        $w = 180;
        $h = 60;
        $img = imagecreatetruecolor($w, $h);

        $bg = imagecolorallocate($img, 243, 246, 252);
        imagefilledrectangle($img, 0, 0, $w, $h, $bg);

        // noise
        for ($i = 0; $i < 6; $i++) {
            $c = imagecolorallocate($img, random_int(190, 230), random_int(190, 230), random_int(220, 245));
            imageline($img, random_int(0, $w), random_int(0, $h), random_int(0, $w), random_int(0, $h), $c);
        }
        for ($i = 0; $i < 220; $i++) {
            $c = imagecolorallocate($img, random_int(150, 220), random_int(150, 220), random_int(150, 220));
            imagesetpixel($img, random_int(0, $w - 1), random_int(0, $h - 1), $c);
        }

        $fonts = glob(SYSTEMPATH . 'fonts/*.{ttf,TTF}', GLOB_BRACE) ?: [];
        for ($i = 0; $i < strlen($code); $i++) {
            $color = imagecolorallocate($img, random_int(10, 90), random_int(30, 100), random_int(120, 200));
            $x = 15 + $i * 32 + random_int(-4, 4);
            $y = random_int(36, 48);
            if ($fonts) {
                imagettftext($img, random_int(22, 26), random_int(-12, 12), $x, $y, $color, $fonts[array_rand($fonts)], $code[$i]);
            } else {
                imagestring($img, 5, $x, $y - 16, $code[$i], $color);
            }
        }

        header('Content-Type: image/png');
        header('Cache-Control: no-store, no-cache, must-revalidate');
        imagepng($img);
        imagedestroy($img);
        exit;
    }
}