<?php

declare(strict_types=1);

use App\App\Bootstrap;
use App\Security\Csrf;
use App\Security\RateLimiter;
use App\Storage\JsonStore;

require dirname(__DIR__) . '/src/autoload.php';
Bootstrap::init();

if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
    http_response_code(405);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Method not allowed';
    exit;
}

$csrf = $_GET['csrf'] ?? '';
if (!Csrf::validate(is_string($csrf) ? $csrf : null)) {
    http_response_code(419);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Ungültiges CSRF-Token.';
    exit;
}

$email = strtolower(trim((string) ($_GET['email'] ?? '')));
if (filter_var($email, FILTER_VALIDATE_EMAIL) === false) {
    http_response_code(422);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Bitte gültige E-Mail eingeben.';
    exit;
}

$field = trim((string) ($_GET['field'] ?? ''));
$index = (int) ($_GET['index'] ?? -1);
if ($field === '' || $index < 0) {
    http_response_code(422);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Ungültiger Upload-Eintrag.';
    exit;
}

/** @return string|null */
function resolveStoredPreviewPath(array $entry, array $app): ?string
{
    $baseDir = rtrim((string) ($app['storage']['uploads'] ?? ''), '/');
    if ($baseDir === '') {
        return null;
    }

    $storedDir = trim((string) ($entry['stored_dir'] ?? ''), '/');
    $storedFilename = trim((string) ($entry['stored_filename'] ?? ''));
    if ($storedDir === '' || $storedFilename === '') {
        return null;
    }
    if (str_contains($storedDir, '..') || str_contains($storedFilename, '..')) {
        return null;
    }
    if (!preg_match('/^[A-Za-z0-9._\/-]+$/', $storedDir)) {
        return null;
    }
    if (!preg_match('/^[A-Za-z0-9._ -]+$/', $storedFilename)) {
        return null;
    }

    $path = $baseDir . '/' . $storedDir . '/' . $storedFilename;
    $realBase = realpath($baseDir);
    $realPath = realpath($path);
    if ($realBase !== false && $realPath !== false && !str_starts_with($realPath, $realBase)) {
        return null;
    }

    return $path;
}

$app = Bootstrap::config('app');
$limiter = new RateLimiter();
$ip = $_SERVER['REMOTE_ADDR'] ?? 'unknown';
$rateKey = sprintf('preview-upload:%s:%s', $ip, $email);
if (!$limiter->allow($rateKey, (int) $app['rate_limit']['requests'], (int) $app['rate_limit']['window_seconds'])) {
    http_response_code(429);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Zu viele Anfragen. Bitte später erneut versuchen.';
    exit;
}

$store = new JsonStore();
$draft = $store->getDraft($email);

if (!is_array($draft)) {
    http_response_code(404);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Entwurf nicht gefunden.';
    exit;
}

$uploads = (array) ($draft['uploads'] ?? []);
$files = $uploads[$field] ?? null;
$entry = (is_array($files) && isset($files[$index]) && is_array($files[$index])) ? $files[$index] : null;
if (!is_array($entry)) {
    http_response_code(404);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Upload nicht gefunden.';
    exit;
}

$path = resolveStoredPreviewPath($entry, $app);
if ($path === null || !is_file($path)) {
    http_response_code(404);
    header('Content-Type: text/plain; charset=utf-8');
    echo 'Datei nicht gefunden.';
    exit;
}

$mime = (string) ($entry['mime'] ?? '');
if ($mime === '') {
    $detected = @mime_content_type($path);
    $mime = is_string($detected) ? $detected : 'application/octet-stream';
}

$downloadName = (string) ($entry['original_filename'] ?? basename($path));
$fallbackName = preg_replace('/[^A-Za-z0-9._-]/', '_', $downloadName) ?: 'upload.bin';
$encodedName = rawurlencode($downloadName);

header('Content-Type: ' . $mime);
header('X-Content-Type-Options: nosniff');
header('Content-Length: ' . (string) filesize($path));
header('Content-Disposition: inline; filename="' . $fallbackName . '"; filename*=UTF-8\'\'' . $encodedName);
readfile($path);
exit;