<?php

declare(strict_types=1);

/**
 * POST /kontakt-senden — Kontaktformular validieren und via Brevo SMTP versenden.
 * Antwort: PRG-Redirect zurück zur absendenden Seite (#kontakt, ?sent=1 | ?error=…)
 *          oder JSON bei fetch (form.js). Das Formular kommt von / wie auch von /kontakt.
 */

use PHPMailer\PHPMailer\PHPMailer;

$field = static fn (string $key): string => trim((string) ($_POST[$key] ?? ''));

// Rücksprungziel gegen die Slug-Whitelist (Single Source of Truth) prüfen — kein Open-Redirect.
$return = $field('return');
$routes = require APP_PATH . '/routes.php';
if (!array_key_exists($return, $routes)) {
    $return = '';
}

$wantsJson = str_contains($_SERVER['HTTP_ACCEPT'] ?? '', 'application/json');

$respond = static function (bool $ok, string $error = '') use ($wantsJson, $return): never {
    if ($wantsJson) {
        header('Content-Type: application/json; charset=utf-8');
        echo json_encode(['ok' => $ok, 'error' => $error ?: null]);
    } else {
        header('Location: ' . url($return) . ($ok ? '?sent=1' : '?error=' . $error) . '#kontakt', true, 303);
    }
    exit;
};

$route = 'kontakt';
$token = $field('ft');

// --- Spam-Checks: Bots bekommen ein stilles "OK" (kein Feedback-Kanal) ---
if ($field('company_url') !== '') {
    log_spam($route, 'honeypot');
    $respond(true);
}
if (!form_token_valid($token)) {
    log_spam($route, 'token');
    $respond(true);
}

// Rate-Limit pro IP (sichtbarer Hinweis statt still — legitime NAT-Nutzer nicht im Dunkeln lassen).
if (!rate_limit_ok('submit|' . $route . '|' . client_ip(), 5, 600)) {
    log_spam($route, 'ratelimit');
    $respond(false, 'ratelimit');
}

// --- Validierung ---
$name = $field('name');
$email = $field('email');
$phone = $field('phone');
$interest = $field('interest');
$subject = $field('subject');
$message = $field('message');

$interests = ['', 'Herrenfußball', 'Frauenfußball', 'Jugendfußball', 'Turnen', 'Sonstiges'];

$valid = $name !== '' && mb_strlen($name) <= 200
    && filter_var($email, FILTER_VALIDATE_EMAIL) !== false
    && mb_strlen($phone) <= 50
    && in_array($interest, $interests, true)
    && $subject !== '' && mb_strlen($subject) <= 200
    && $message !== '' && mb_strlen($message) <= 5000
    && ($_POST['privacy'] ?? '') === '1'
    && !preg_match('/[\r\n]/', $name . $subject);

if (!$valid) {
    $respond(false, 'validation');
}

// --- Inhalts-/Aufkommens-Heuristiken (still abweisen, Bot-typisch) ---
if (preg_match_all('~https?://~i', $subject . ' ' . $message) > 2) {
    log_spam($route, 'links');
    $respond(true);
}
// Globaler Tages-Cap als Brevo-Kosten-Backstop — die Flut soll ihn nicht bemerken.
if (!rate_limit_ok('daily', 100, 86400)) {
    log_spam($route, 'daily-cap');
    $respond(true);
}
// Token-Mehrfachnutzung begrenzen (Replay-Schutz, großzügig für menschliches Mehrfach-Senden).
if (!rate_limit_ok('token|' . $token, 3, 86400)) {
    log_spam($route, 'replay');
    $respond(true);
}

// --- Versand ---
$smtp = config('smtp');

$body = "Kontaktanfrage über tsv08kulmbach.de\n"
    . str_repeat('-', 40) . "\n"
    . "Name:      {$name}\n"
    . "E-Mail:    {$email}\n"
    . ($phone !== '' ? "Telefon:   {$phone}\n" : '')
    . ($interest !== '' ? "Interesse: {$interest}\n" : '')
    . "Betreff:   {$subject}\n"
    . str_repeat('-', 40) . "\n\n"
    . $message . "\n\n"
    . str_repeat('-', 40) . "\n"
    . 'Datenschutz zugestimmt: ja (' . date('d.m.Y H:i') . ")\n";

try {
    $mail = new PHPMailer(true);
    $mail->isSMTP();
    $mail->Host = $smtp['host'];
    $mail->Port = (int) $smtp['port'];
    $mail->SMTPAuth = true;
    $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    $mail->Username = $smtp['username'];
    $mail->Password = $smtp['password'];
    $mail->CharSet = PHPMailer::CHARSET_UTF8;

    $mail->setFrom($smtp['from'], $smtp['from_name']);
    $mail->addAddress($smtp['to']);
    $mail->addReplyTo($email, $name);
    $mail->Subject = 'Kontaktanfrage: ' . $subject;
    $mail->Body = $body;

    $mail->send();
} catch (Throwable $e) {
    error_log('[' . date('c') . '] Mailversand fehlgeschlagen: ' . $e->getMessage() . "\n", 3, STORAGE_PATH . '/logs/mail.log');
    $respond(false, 'mail');
}

$respond(true);