<?php
/**
 * Wiki Newsletter - Thomas-Krenn Wiki
 *
 * Voraussetzungen:
 *   composer require phpmailer/phpmailer
 *
 * Aufruf im Browser:
 *   https://deine-domain.tld/wiki-newsletter.php
 *
 * Cronjob monatlich:
 *   0 8 1 * * /usr/bin/php /pfad/wiki-newsletter.php --cron --token='DEIN_CRON_TOKEN'
 */

declare(strict_types=1);

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception as MailException;

session_start();

require_once __DIR__ . '/vendor/autoload.php';

const ADMIN_PASSWORD = 'CHANGE_ME_ADMIN_PASSWORD'; // Unbedingt ändern!
const CONFIG_FILE = __DIR__ . '/newsletter-config.json';
const STATE_FILE  = __DIR__ . '/newsletter-state.json';

$defaultConfig = [
    'wiki_url'             => 'https://www.thomas-krenn.com/de/wiki/Neueste_Artikel',
    'article_limit'        => 20,
    'article_fetch_limit'  => 150,
    'period_mode'          => 'previous_month', // previous_month oder current_month

    'smtp_host'            => '',
    'smtp_port'            => 587,
    'smtp_encryption'      => 'tls', // tls, ssl, none
    'smtp_user'            => '',
    'smtp_pass'            => '',

    'from_email'           => '',
    'from_name'            => 'Wiki-Team',
    'recipient_email'      => '',
    'test_recipient_email' => '',

    'subject'              => 'Wiki Newsletter - {MONAT}',
    'firstname'            => 'zusammen',
    'reply_to'             => '',
    'unsubscribe_url'      => '#',
    'cron_token'           => bin2hex(random_bytes(24)),
];

function h(?string $value): string
{
    return htmlspecialchars((string)$value, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
}

function loadJsonFile(string $file, array $default): array
{
    if (!is_file($file)) {
        return $default;
    }

    $json = file_get_contents($file);
    $data = json_decode((string)$json, true);

    if (!is_array($data)) {
        return $default;
    }

    return array_replace($default, $data);
}

function saveJsonFile(string $file, array $data): void
{
    file_put_contents(
        $file,
        json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE),
        LOCK_EX
    );
}

function isAdminLoggedIn(): bool
{
    if (ADMIN_PASSWORD === 'CHANGE_ME_ADMIN_PASSWORD') {
        return true; // Ersteinrichtung. Danach ADMIN_PASSWORD ändern.
    }

    return !empty($_SESSION['wiki_newsletter_admin']);
}

function requireAdmin(): void
{
    if (!isAdminLoggedIn()) {
        http_response_code(403);
        exit('Nicht angemeldet.');
    }
}

function cliArg(string $name): ?string
{
    global $argv;

    foreach (($argv ?? []) as $arg) {
        if ($arg === '--' . $name) {
            return '1';
        }

        if (str_starts_with($arg, '--' . $name . '=')) {
            return substr($arg, strlen('--' . $name . '='));
        }
    }

    return null;
}

function fetchUrl(string $url): string
{
    $ch = curl_init($url);
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_FOLLOWLOCATION => true,
        CURLOPT_TIMEOUT        => 25,
        CURLOPT_CONNECTTIMEOUT => 10,
        CURLOPT_USERAGENT      => 'Wiki-Newsletter/1.0 (+https://www.thomas-krenn.com/de/wiki/Hauptseite)',
        CURLOPT_HTTPHEADER     => ['Accept: text/html,application/xhtml+xml'],
    ]);

    $html = curl_exec($ch);
    $error = curl_error($ch);
    $code = (int)curl_getinfo($ch, CURLINFO_RESPONSE_CODE);
    curl_close($ch);

    if ($html === false || $code >= 400) {
        throw new RuntimeException('Wiki konnte nicht geladen werden. HTTP-Code: ' . $code . ' Fehler: ' . $error);
    }

    return (string)$html;
}

function absoluteWikiUrl(string $href): string
{
    if (preg_match('~^https?://~i', $href)) {
        return $href;
    }

    if (str_starts_with($href, '//')) {
        return 'https:' . $href;
    }

    if (str_starts_with($href, '/')) {
        return 'https://www.thomas-krenn.com' . $href;
    }

    return 'https://www.thomas-krenn.com/de/wiki/' . ltrim($href, '/');
}

function fetchLatestArticles(string $wikiUrl, int $limit = 150): array
{
    $html = fetchUrl($wikiUrl);

    $articles = [];

    if (class_exists('DOMDocument') && class_exists('DOMXPath')) {
        libxml_use_internal_errors(true);
        $dom = new DOMDocument();
        $dom->loadHTML('<?xml encoding="UTF-8">' . $html, LIBXML_NOWARNING | LIBXML_NOERROR);
        libxml_clear_errors();

        $xpath = new DOMXPath($dom);
        $nodes = $xpath->query('//li');

        foreach ($nodes as $li) {
            $text = trim(preg_replace('/\s+/', ' ', $li->textContent ?? ''));

            if (!preg_match('/\((\d{2}\.\d{2}\.\d{4})\)/', $text, $dateMatch)) {
                continue;
            }

            $links = $li->getElementsByTagName('a');

            if ($links->length < 1) {
                continue;
            }

            $title = trim($links->item(0)->textContent ?? '');
            $href  = trim($links->item(0)->getAttribute('href'));

            if ($title === '' || $href === '') {
                continue;
            }

            $author = 'Unbekannt';
            if ($links->length >= 2) {
                $author = trim($links->item(1)->textContent ?? 'Unbekannt');
            }

            $date = DateTimeImmutable::createFromFormat('d.m.Y', $dateMatch[1]);
            if (!$date) {
                continue;
            }

            $articles[] = [
                'title'      => $title,
                'url'        => absoluteWikiUrl($href),
                'date'       => $date->format('Y-m-d'),
                'date_de'    => $date->format('d.m.Y'),
                'author'     => $author,
                'sourceText' => $text,
            ];

            if (count($articles) >= $limit) {
                break;
            }
        }
    } else {
        // Fallback ohne ext-dom: robuster Regex-Parser für die Wiki-Liste
        if (preg_match_all('/<li\b[^>]*>(.*?)<\/li>/is', $html, $liMatches)) {
            foreach ($liMatches[1] as $liHtml) {
                $text = trim(preg_replace('/\s+/', ' ', strip_tags($liHtml)));
                if (!preg_match('/\((\d{2}\.\d{2}\.\d{4})\)/', $text, $dateMatch)) {
                    continue;
                }

                preg_match_all('/<a\b[^>]*href=(["\'])(.*?)\1[^>]*>(.*?)<\/a>/is', $liHtml, $linkMatches, PREG_SET_ORDER);
                if (count($linkMatches) < 1) {
                    continue;
                }

                $title = trim(html_entity_decode(strip_tags($linkMatches[0][3]), ENT_QUOTES | ENT_HTML5, 'UTF-8'));
                $href  = trim(html_entity_decode($linkMatches[0][2], ENT_QUOTES | ENT_HTML5, 'UTF-8'));
                if ($title === '' || $href === '') {
                    continue;
                }

                $author = 'Unbekannt';
                if (count($linkMatches) >= 2) {
                    $author = trim(html_entity_decode(strip_tags($linkMatches[1][3]), ENT_QUOTES | ENT_HTML5, 'UTF-8'));
                    if ($author === '') {
                        $author = 'Unbekannt';
                    }
                }

                $date = DateTimeImmutable::createFromFormat('d.m.Y', $dateMatch[1]);
                if (!$date) {
                    continue;
                }

                $articles[] = [
                    'title'      => $title,
                    'url'        => absoluteWikiUrl($href),
                    'date'       => $date->format('Y-m-d'),
                    'date_de'    => $date->format('d.m.Y'),
                    'author'     => $author,
                    'sourceText' => $text,
                ];

                if (count($articles) >= $limit) {
                    break;
                }
            }
        }
    }

    return $articles;
}

function germanMonthName(int $month): string
{
    $months = [
        1 => 'Januar', 2 => 'Februar', 3 => 'März', 4 => 'April',
        5 => 'Mai', 6 => 'Juni', 7 => 'Juli', 8 => 'August',
        9 => 'September', 10 => 'Oktober', 11 => 'November', 12 => 'Dezember'
    ];

    return $months[$month] ?? (string)$month;
}

function newsletterPeriod(string $mode): array
{
    $now = new DateTimeImmutable('now');

    if ($mode === 'current_month') {
        $start = $now->modify('first day of this month')->setTime(0, 0, 0);
        $end   = $now->modify('first day of next month')->setTime(0, 0, 0);
    } else {
        $start = $now->modify('first day of previous month')->setTime(0, 0, 0);
        $end   = $now->modify('first day of this month')->setTime(0, 0, 0);
    }

    $label = germanMonthName((int)$start->format('n')) . ' ' . $start->format('Y');
    $key   = $start->format('Y-m');

    return [$start, $end, $label, $key];
}

function filterArticlesForPeriod(array $articles, DateTimeImmutable $start, DateTimeImmutable $end, int $limit): array
{
    $filtered = [];

    foreach ($articles as $article) {
        $date = new DateTimeImmutable($article['date'] . ' 00:00:00');

        if ($date >= $start && $date < $end) {
            $filtered[] = $article;
        }

        if (count($filtered) >= $limit) {
            break;
        }
    }

    return $filtered;
}

function subjectFromTemplate(string $subject, string $periodLabel, int $count): string
{
    return str_replace(
        ['{MONAT}', '{ANZAHL}'],
        [$periodLabel, (string)$count],
        $subject
    );
}

function newsletterHtmlFragmentForClipboard(string $html): string
{
    if (preg_match('/<body[^>]*>(.*)<\/body>/is', $html, $matches)) {
        return trim($matches[1]);
    }

    return trim($html);
}

function buildNewsletterHtml(array $config, array $articles, string $periodLabel, bool $isTest = false): string
{
    $count = count($articles);
    $preheader = $count === 1
        ? '1 neuer Wiki-Artikel im ' . $periodLabel
        : $count . ' neue Wiki-Artikel im ' . $periodLabel;

    $replyEmail = trim((string)($config['reply_to'] ?: $config['from_email']));
    $replyHref = 'mailto:' . $replyEmail;

    $summaryText = $count === 1
        ? 'Im ' . h($periodLabel) . ' wurde 1 neuer Wiki-Artikel veröffentlicht.'
        : 'Im ' . h($periodLabel) . ' wurden ' . $count . ' neue Wiki-Artikel veröffentlicht.';

    $testBadge = $isTest
        ? '<tr>
             <td style="padding:0 24px 12px 24px;" class="mobile-padding">
               <table role="presentation" border="0" cellspacing="0" cellpadding="0">
                 <tr>
                   <td bgcolor="#fff3cd" style="background-color:#fff3cd;border:1px solid #f4d58a;padding:6px 10px;font-family:Arial,Helvetica,sans-serif;font-size:11px;line-height:15px;font-weight:700;color:#7a5200;">
                     TESTVERSAND
                   </td>
                 </tr>
               </table>
             </td>
           </tr>'
        : '';

    $articleRows = '';
    if ($count === 0) {
        $articleRows = '
          <tr>
            <td style="padding:0 24px 18px 24px;" class="mobile-padding">
              <table role="presentation" width="100%" border="0" cellspacing="0" cellpadding="0" style="width:100%;border:1px solid #d7d7d7;background:#ffffff;">
                <tr>
                  <td style="padding:18px;font-family:Arial,Helvetica,sans-serif;font-size:14px;line-height:21px;color:#333333;">
                    Für diesen Zeitraum wurden keine neuen Artikel gefunden.
                  </td>
                </tr>
              </table>
            </td>
          </tr>';
    } else {
        foreach ($articles as $article) {
            $articleRows .= '
          <tr>
            <td style="padding:0 24px 18px 24px;" class="mobile-padding">
              <table role="presentation" width="100%" border="0" cellspacing="0" cellpadding="0" style="width:100%;background:#ffffff;">
                <tr>
                  <td style="padding:0 0 5px 0;font-family:Arial,Helvetica,sans-serif;font-size:12px;line-height:17px;color:#595959;">
                    Thomas-Krenn-Wiki
                  </td>
                </tr>
                <tr>
                  <td style="padding:0 0 5px 0;font-family:Arial,Helvetica,sans-serif;font-size:22px;line-height:28px;font-weight:700;color:#ef7d00;">
                    <a href="' . h($article['url']) . '" target="_blank" style="color:#ef7d00;text-decoration:none;">' . h($article['title']) . '</a>
                  </td>
                </tr>
                <tr>
                  <td style="padding:0 0 10px 0;font-family:Arial,Helvetica,sans-serif;font-size:14px;line-height:22px;color:#2e2e2e;">
                    Veröffentlicht am ' . h($article['date_de']) . ' von ' . h($article['author']) . '.
                  </td>
                </tr>
                <tr>
                  <td style="padding:0;">
                    <table role="presentation" border="0" cellspacing="0" cellpadding="0">
                      <tr>
                        <td bgcolor="#ef7d00" style="background:#ef7d00;">
                          <a href="' . h($article['url']) . '" target="_blank" style="display:inline-block;padding:8px 14px;font-family:Arial,Helvetica,sans-serif;font-size:13px;line-height:16px;color:#ffffff;text-decoration:none;">Jetzt Artikel lesen</a>
                        </td>
                      </tr>
                    </table>
                  </td>
                </tr>
              </table>
            </td>
          </tr>';
        }
    }

    $unsubscribeFooter = '';
    $unsubscribeUrl = trim((string)($config['unsubscribe_url'] ?? ''));
    if ($unsubscribeUrl !== '' && $unsubscribeUrl !== '#' && filter_var($unsubscribeUrl, FILTER_VALIDATE_URL)) {
        $unsubscribeFooter = '<br><a href="' . h($unsubscribeUrl) . '" target="_blank" style="color:#ef7d00;text-decoration:underline;">Abmelden</a>';
    }

    return '<!doctype html>
<html lang="de" xmlns="http://www.w3.org/1999/xhtml" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width,initial-scale=1">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Thomas-Krenn Wiki Newsletter</title>
  <style type="text/css">
    html, body { margin:0 !important; padding:0 !important; width:100% !important; background:#e6e6e6; }
    table, td { border-collapse:collapse; mso-table-lspace:0pt; mso-table-rspace:0pt; }
    img { border:0; outline:none; text-decoration:none; -ms-interpolation-mode:bicubic; display:block; }
    a { text-decoration:none; }
    * { -ms-text-size-adjust:100%; -webkit-text-size-adjust:100%; }
    .preheader { display:none !important; visibility:hidden; opacity:0; color:transparent; height:0; width:0; max-height:0; max-width:0; overflow:hidden; mso-hide:all; }
    @media only screen and (max-width: 640px) {
      .email-container { width:100% !important; }
      .mobile-padding { padding-left:14px !important; padding-right:14px !important; }
      .mobile-body { font-size:15px !important; line-height:23px !important; }
      .mobile-title { font-size:19px !important; line-height:25px !important; }
    }
  </style>
</head>
<body style="margin:0;padding:0;background:#e6e6e6;">
  <div class="preheader">' . h($preheader) . '&nbsp;&zwnj;&nbsp;&zwnj;&nbsp;&zwnj;</div>
  <center role="article" aria-roledescription="email" lang="de" style="width:100%;background:#e6e6e6;">
    <table role="presentation" width="100%" border="0" cellspacing="0" cellpadding="0" bgcolor="#e6e6e6" style="width:100%;background:#e6e6e6;">
      <tr>
        <td align="center" style="padding:6px 8px;">
          <table role="presentation" width="620" border="0" cellspacing="0" cellpadding="0" class="email-container" style="width:100%;max-width:620px;background:#ffffff;">
            <tr>
              <td align="center" style="padding:8px 20px 6px 20px;font-family:Arial,Helvetica,sans-serif;font-size:11px;line-height:15px;color:#4e4e4e;">
                Sollte diese E-Mail nicht einwandfrei dargestellt werden, klicken Sie bitte hier.
              </td>
            </tr>
            <tr>
              <td align="center" style="padding:4px 20px 10px 20px;font-family:Arial,Helvetica,sans-serif;font-size:30px;line-height:32px;font-weight:700;color:#555555;">
                THOMAS<br>KRENN
              </td>
            </tr>
            <tr>
              <td style="padding:0 24px;" class="mobile-padding">
                <table role="presentation" width="100%" border="0" cellspacing="0" cellpadding="0" style="width:100%;background:#142232;">
                  <tr>
                    <td style="padding:16px 14px;font-family:Arial,Helvetica,sans-serif;color:#ffffff;">
                      <div style="font-size:12px;line-height:16px;font-weight:700;letter-spacing:0.6px;color:#ef7d00;">NEWSLETTER</div>
                      <div class="mobile-title" style="font-size:24px;line-height:30px;font-weight:700;color:#ffffff;">' . h($periodLabel) . '</div>
                    </td>
                  </tr>
                </table>
              </td>
            </tr>
            <tr>
              <td style="padding:10px 24px 8px 24px;background:#f3f3f3;" class="mobile-padding">
                <table role="presentation" width="100%" border="0" cellspacing="0" cellpadding="0">
                  <tr>
                    <td class="mobile-body" style="font-family:Arial,Helvetica,sans-serif;font-size:14px;line-height:21px;color:#1f1f1f;">
                      Guten Tag,<br><br>
                      „oh mei“ sagen wir in Bayern, wenn mal was schiefgeht. In diesem Newsletter finden Sie aktuelles und kostenfreies IT-Know-how aus dem Thomas-Krenn-Wiki.
                      <br><br>' . $summaryText . '
                      <br><br>Viel Spaß beim Lesen wünscht<br>Ihr Team von Thomas-Krenn
                    </td>
                  </tr>
                </table>
              </td>
            </tr>
            ' . $testBadge . '
            ' . $articleRows . '
            <tr>
              <td style="padding:0 24px 18px 24px;" class="mobile-padding">
                <table role="presentation" width="100%" border="0" cellspacing="0" cellpadding="0" style="width:100%;">
                  <tr>
                    <td style="font-family:Arial,Helvetica,sans-serif;font-size:14px;line-height:22px;color:#2e2e2e;">
                      Haben Sie Fragen oder einen Themenwunsch?
                      <a href="' . h($replyHref) . '" style="color:#ef7d00;text-decoration:underline;">Kontaktieren Sie uns gerne direkt.</a>
                    </td>
                  </tr>
                </table>
              </td>
            </tr>
            <tr>
              <td style="background:#ececec;padding:18px 24px;text-align:center;font-family:Arial,Helvetica,sans-serif;">
                <div style="font-size:12px;line-height:18px;color:#666666;">
                  Tel.: +49 8551 9150 0 | Fax: +49 8551 9150 55<br>
                  <a href="https://www.thomas-krenn.com/de/wiki/Hauptseite" target="_blank" style="color:#ef7d00;text-decoration:underline;">thomas-krenn.com</a><br><br>
                  Thomas-Krenn.AG | Speltenbach-Steinäcker 1 | D-94078 Freyung
                  ' . $unsubscribeFooter . '
                </div>
              </td>
            </tr>
          </table>
        </td>
      </tr>
    </table>
  </center>
</body>
</html>';
}


function buildPlainText(array $config, array $articles, string $periodLabel, bool $isTest = false): string
{
    $lines = [];
    if ($isTest) {
        $lines[] = '[TESTVERSAND]';
        $lines[] = '';
    }

    $lines[] = 'Wiki Newsletter';
    $lines[] = '';
    $lines[] = 'Servus,';
    $lines[] = '';
    $lines[] = 'das Wiki-Team hat im ' . $periodLabel . ' ' . count($articles) . ' Artikel für das Forum veröffentlicht!';
    $lines[] = '';

    if (empty($articles)) {
        $lines[] = 'Für diesen Zeitraum wurden keine neuen Artikel gefunden.';
    } else {
        foreach ($articles as $article) {
            $lines[] = '- ' . $article['title'] . ' von ' . $article['author'] . ' | ' . $article['date_de'];
            $lines[] = '  ' . $article['url'];
        }
    }

    $lines[] = '';
    $lines[] = 'Du hast Vorschläge, Ideen oder möchtest selber einen Artikel veröffentlichen?';
    $lines[] = 'Dann schreib uns eine Mail: ' . ($config['reply_to'] ?: $config['from_email']);

    return implode("\n", $lines);
}

function validateConfig(array $config): void
{
    $required = [
        'smtp_host'       => 'SMTP-Host',
        'smtp_port'       => 'SMTP-Port',
        'from_email'      => 'Absender-Mail',
        'recipient_email' => 'Empfänger-Mail',
    ];

    foreach ($required as $key => $label) {
        if (trim((string)$config[$key]) === '') {
            throw new RuntimeException($label . ' fehlt.');
        }
    }

    foreach (['from_email', 'recipient_email'] as $mailKey) {
        if (!filter_var($config[$mailKey], FILTER_VALIDATE_EMAIL)) {
            throw new RuntimeException($mailKey . ' ist keine gültige E-Mail-Adresse.');
        }
    }

    if (!empty($config['test_recipient_email']) && !filter_var($config['test_recipient_email'], FILTER_VALIDATE_EMAIL)) {
        throw new RuntimeException('Test-Empfänger ist keine gültige E-Mail-Adresse.');
    }

    if (!empty($config['reply_to']) && !filter_var($config['reply_to'], FILTER_VALIDATE_EMAIL)) {
        throw new RuntimeException('Reply-To ist keine gültige E-Mail-Adresse.');
    }
}

function sendMail(array $config, string $to, string $subject, string $html, string $plain): void
{
    validateConfig($config);

    $mail = new PHPMailer(true);
    $mail->CharSet = 'UTF-8';
    $mail->Encoding = 'base64';
    $mail->WordWrap = 78;
    $mail->XMailer = 'Thomas-Krenn Wiki Newsletter';
    $mail->isSMTP();
    $mail->Host = $config['smtp_host'];
    $mail->Port = (int)$config['smtp_port'];
    $mail->SMTPAuth = trim((string)$config['smtp_user']) !== '' || trim((string)$config['smtp_pass']) !== '';

    if ($mail->SMTPAuth) {
        $mail->Username = $config['smtp_user'];
        $mail->Password = $config['smtp_pass'];
    }

    if ($config['smtp_encryption'] === 'tls') {
        $mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
    } elseif ($config['smtp_encryption'] === 'ssl') {
        $mail->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
    } else {
        $mail->SMTPSecure = false;
        $mail->SMTPAutoTLS = false;
    }

    $mail->setFrom($config['from_email'], $config['from_name'] ?: 'Wiki-Team');

    if (!empty($config['reply_to'])) {
        $mail->addReplyTo($config['reply_to']);
    }

    $unsubscribeUrl = trim((string)($config['unsubscribe_url'] ?? ''));
    if ($unsubscribeUrl !== '' && $unsubscribeUrl !== '#' && filter_var($unsubscribeUrl, FILTER_VALIDATE_URL)) {
        $mail->addCustomHeader('List-Unsubscribe', '<' . $unsubscribeUrl . '>');
    }

    $mail->addAddress($to);
    $mail->Subject = $subject;
    $mail->isHTML(true);
    $mail->Body = $html;
    $mail->AltBody = $plain;

    $mail->send();
}

function newsletterData(array $config, bool $testMode = false): array
{
    [$start, $end, $periodLabel, $periodKey] = newsletterPeriod($config['period_mode']);
    $allArticles = fetchLatestArticles($config['wiki_url'], (int)$config['article_fetch_limit']);

    if ($testMode) {
        $articles = array_slice($allArticles, 0, (int)$config['article_limit']);
        $periodLabel = 'aktuelle Übersicht';
        $periodKey = 'test-' . date('Y-m-d-H-i-s');
    } else {
        $articles = filterArticlesForPeriod($allArticles, $start, $end, (int)$config['article_limit']);
    }

    return [$articles, $periodLabel, $periodKey];
}

function sendNewsletter(array $config, bool $testMode = false): string
{
    [$articles, $periodLabel] = newsletterData($config, $testMode);

    $to = $testMode && !empty($config['test_recipient_email'])
        ? $config['test_recipient_email']
        : $config['recipient_email'];

    $subject = subjectFromTemplate($config['subject'], $periodLabel, count($articles));
    if ($testMode) {
        $subject = '[TEST] ' . $subject;
    }

    $html  = buildNewsletterHtml($config, $articles, $periodLabel, $testMode);
    $plain = buildPlainText($config, $articles, $periodLabel, $testMode);

    sendMail($config, $to, $subject, $html, $plain);

    return 'Newsletter wurde an ' . $to . ' gesendet. Artikel: ' . count($articles);
}

function sendMonthlyIfDue(array $config): string
{
    [$articles, $periodLabel, $periodKey] = newsletterData($config, false);
    $state = loadJsonFile(STATE_FILE, []);

    if (($state['last_sent_period'] ?? '') === $periodKey) {
        return 'Monatsnewsletter für ' . $periodLabel . ' wurde bereits gesendet. Kein erneuter Versand.';
    }

    $subject = subjectFromTemplate($config['subject'], $periodLabel, count($articles));
    $html = buildNewsletterHtml($config, $articles, $periodLabel, false);
    $plain = buildPlainText($config, $articles, $periodLabel, false);

    sendMail($config, $config['recipient_email'], $subject, $html, $plain);

    $state['last_sent_period'] = $periodKey;
    $state['last_sent_at'] = date('c');
    $state['last_article_count'] = count($articles);
    saveJsonFile(STATE_FILE, $state);

    return 'Monatsnewsletter für ' . $periodLabel . ' wurde gesendet. Artikel: ' . count($articles);
}

function configFromPost(array $current): array
{
    $fields = [
        'wiki_url', 'article_limit', 'article_fetch_limit', 'period_mode',
        'smtp_host', 'smtp_port', 'smtp_encryption', 'smtp_user',
        'from_email', 'from_name', 'recipient_email', 'test_recipient_email',
        'subject', 'reply_to', 'unsubscribe_url', 'cron_token'
    ];

    foreach ($fields as $field) {
        if (isset($_POST[$field])) {
            $current[$field] = trim((string)$_POST[$field]);
        }
    }

    if (isset($_POST['smtp_pass']) && trim((string)$_POST['smtp_pass']) !== '') {
        $current['smtp_pass'] = (string)$_POST['smtp_pass'];
    }

    $current['article_limit'] = max(1, min(100, (int)$current['article_limit']));
    $current['article_fetch_limit'] = max($current['article_limit'], min(500, (int)$current['article_fetch_limit']));
    $current['smtp_port'] = (int)$current['smtp_port'];

    if (!in_array($current['smtp_encryption'], ['tls', 'ssl', 'none'], true)) {
        $current['smtp_encryption'] = 'tls';
    }

    if (!in_array($current['period_mode'], ['previous_month', 'current_month'], true)) {
        $current['period_mode'] = 'previous_month';
    }

    if (trim($current['cron_token']) === '') {
        $current['cron_token'] = bin2hex(random_bytes(24));
    }

    return $current;
}

$config = loadJsonFile(CONFIG_FILE, $defaultConfig);
$message = '';
$error = '';
$previewHtml = '';
$previewClipboardHtml = '';

$isCron = (PHP_SAPI === 'cli' && cliArg('cron') !== null) || isset($_GET['cron']);

if ($isCron) {
    $givenToken = PHP_SAPI === 'cli' ? (cliArg('token') ?? '') : (string)($_GET['cron'] ?? '');

    if (!hash_equals((string)$config['cron_token'], (string)$givenToken)) {
        http_response_code(403);
        exit("Ungültiger Cron-Token.\n");
    }

    try {
        echo sendMonthlyIfDue($config) . "\n";
    } catch (Throwable $e) {
        http_response_code(500);
        echo 'Fehler: ' . $e->getMessage() . "\n";
    }
    exit;
}

if ($_SERVER['REQUEST_METHOD'] === 'POST' && ($_POST['action'] ?? '') === 'login') {
    if (ADMIN_PASSWORD !== 'CHANGE_ME_ADMIN_PASSWORD' && hash_equals(ADMIN_PASSWORD, (string)($_POST['admin_password'] ?? ''))) {
        $_SESSION['wiki_newsletter_admin'] = true;
        header('Location: ' . strtok($_SERVER['REQUEST_URI'], '?'));
        exit;
    }
    $error = 'Falsches Admin-Passwort.';
}

if ($_SERVER['REQUEST_METHOD'] === 'POST' && ($_POST['action'] ?? '') !== 'login') {
    try {
        requireAdmin();
        $config = configFromPost($config);
        saveJsonFile(CONFIG_FILE, $config);

        $action = $_POST['action'] ?? 'save';

        if ($action === 'save') {
            $message = 'Einstellungen gespeichert.';
        } elseif ($action === 'preview') {
            [$articles, $periodLabel] = newsletterData($config, true);
            $previewHtml = buildNewsletterHtml($config, $articles, $periodLabel, true);
            $previewClipboardHtml = newsletterHtmlFragmentForClipboard($previewHtml);
            $message = 'Vorschau wurde erstellt. Einstellungen wurden gespeichert.';
        } elseif ($action === 'test_send') {
            $message = sendNewsletter($config, true);
        } elseif ($action === 'monthly_send') {
            $message = sendMonthlyIfDue($config);
        }
    } catch (Throwable $e) {
        $error = $e->getMessage();
    }
}

$isLoggedIn = isAdminLoggedIn();
?>
<!doctype html>
<html lang="de">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Wiki Newsletter Admin</title>
  <style>
    :root {
      --bg: #f5f7fa;
      --card: #ffffff;
      --text: #111827;
      --muted: #6b7280;
      --border: #e5e7eb;
      --primary: #2563eb;
      --primary-soft: #eff6ff;
      --accent: #f97316;
      --danger: #dc2626;
      --ok: #16a34a;
      --radius: 18px;
      --shadow: 0 24px 60px rgba(15, 23, 42, .08);
    }
    * { box-sizing: border-box; }
    body {
      margin: 0;
      padding: 40px 16px;
      background: var(--bg);
      font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
      color: var(--text);
    }
    .wrap { max-width: 1040px; margin: 0 auto; }
    .hero {
      padding: 34px 38px;
      border-radius: 24px;
      background: linear-gradient(135deg, rgba(37,99,235,.08), rgba(249,115,22,.08)), #fff;
      border: 1px solid var(--border);
      box-shadow: var(--shadow);
      margin-bottom: 22px;
    }
    .hero h1 { margin: 0; font-size: 38px; letter-spacing: -.04em; }
    .hero p { margin: 10px 0 0; color: var(--muted); font-size: 16px; line-height: 1.6; }
    .grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
    .card {
      background: var(--card);
      border: 1px solid var(--border);
      border-radius: var(--radius);
      box-shadow: 0 14px 36px rgba(15,23,42,.05);
      padding: 24px;
    }
    .card.full { grid-column: 1 / -1; }
    h2 { margin: 0 0 18px; font-size: 21px; letter-spacing: -.02em; }
    label { display: block; margin: 14px 0 7px; color: #374151; font-size: 14px; font-weight: 700; }
    input, select {
      width: 100%;
      height: 42px;
      padding: 0 12px;
      border: 1px solid var(--border);
      border-radius: 12px;
      background: #fff;
      color: var(--text);
      font-size: 14px;
      outline: none;
    }
    input:focus, select:focus { border-color: rgba(37,99,235,.55); box-shadow: 0 0 0 4px rgba(37,99,235,.08); }
    .hint { margin: 7px 0 0; color: var(--muted); font-size: 13px; line-height: 1.5; }
    .actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 22px; }
    button {
      height: 42px;
      padding: 0 16px;
      border: 0;
      border-radius: 12px;
      background: var(--primary);
      color: #fff;
      font-weight: 800;
      cursor: pointer;
    }
    button.secondary { background: #111827; }
    button.light { background: var(--primary-soft); color: var(--primary); }
    button.warn { background: var(--accent); }
    .notice, .error, .warning {
      margin-bottom: 18px;
      padding: 14px 16px;
      border-radius: 14px;
      font-weight: 700;
      line-height: 1.5;
    }
    .notice { background: #ecfdf5; color: #166534; border: 1px solid #bbf7d0; }
    .error { background: #fef2f2; color: #991b1b; border: 1px solid #fecaca; }
    .warning { background: #fffbeb; color: #92400e; border: 1px solid #fde68a; }
    code { padding: 2px 6px; border-radius: 7px; background: #f3f4f6; }
    .preview { width: 100%; min-height: 760px; border: 1px solid var(--border); border-radius: 16px; background: #fff; }
    .preview-toolbar {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 14px;
    }
    .preview-toolbar p { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.5; max-width: 520px; }
    .preview-source {
      display: none;
    }
    .outlook-copy-buffer {
      position: fixed;
      left: -10000px;
      top: 0;
      width: 720px;
      opacity: 0;
      pointer-events: none;
    }
    .copy-status {
      margin-top: 10px;
      color: var(--ok);
      font-size: 13px;
      font-weight: 700;
      min-height: 20px;
    }
    @media (max-width: 820px) { .grid { grid-template-columns: 1fr; } .hero { padding: 28px 24px; } }
  </style>
</head>
<body>
  <div class="wrap">
    <section class="hero">
      <h1>Wiki Newsletter Admin</h1>
      <p>Holt die neuesten Artikel aus dem Thomas-Krenn-Wiki, erstellt daraus einen modernen Newsletter und versendet ihn über SMTP.</p>
    </section>

    <?php if (ADMIN_PASSWORD === 'CHANGE_ME_ADMIN_PASSWORD'): ?>
      <div class="warning">Wichtig: Bitte oben im PHP-Code <code>ADMIN_PASSWORD</code> ändern, bevor die Seite öffentlich erreichbar ist.</div>
    <?php endif; ?>

    <?php if ($message !== ''): ?><div class="notice"><?= h($message) ?></div><?php endif; ?>
    <?php if ($error !== ''): ?><div class="error"><?= h($error) ?></div><?php endif; ?>

    <?php if (!$isLoggedIn): ?>
      <form method="post" class="card">
        <input type="hidden" name="action" value="login">
        <h2>Anmeldung</h2>
        <label>Admin-Passwort</label>
        <input type="password" name="admin_password" autocomplete="current-password" required>
        <div class="actions"><button type="submit">Einloggen</button></div>
      </form>
    <?php else: ?>
      <form method="post">
        <div class="grid">
          <section class="card">
            <h2>Wiki & Newsletter</h2>

            <label>Wiki-Quelle</label>
            <input name="wiki_url" value="<?= h($config['wiki_url']) ?>">
            <p class="hint">Standard: Thomas-Krenn „Neueste Artikel“.</p>

            <label>Zeitraum</label>
            <select name="period_mode">
              <option value="previous_month" <?= $config['period_mode'] === 'previous_month' ? 'selected' : '' ?>>Vorheriger Monat</option>
              <option value="current_month" <?= $config['period_mode'] === 'current_month' ? 'selected' : '' ?>>Aktueller Monat</option>
            </select>

            <label>Max. Artikel im Newsletter</label>
            <input type="number" name="article_limit" min="1" max="100" value="<?= h((string)$config['article_limit']) ?>">

            <label>Max. Artikel von Wiki abrufen</label>
            <input type="number" name="article_fetch_limit" min="1" max="500" value="<?= h((string)$config['article_fetch_limit']) ?>">

            <label>Betreff</label>
            <input name="subject" value="<?= h($config['subject']) ?>">
            <p class="hint">Platzhalter: <code>{MONAT}</code>, <code>{ANZAHL}</code></p>

          </section>

          <section class="card">
            <h2>SMTP Einstellungen</h2>

            <label>SMTP Host</label>
            <input name="smtp_host" value="<?= h($config['smtp_host']) ?>" placeholder="smtp.example.com">

            <label>SMTP Port</label>
            <input type="number" name="smtp_port" value="<?= h((string)$config['smtp_port']) ?>">

            <label>Verschlüsselung</label>
            <select name="smtp_encryption">
              <option value="tls" <?= $config['smtp_encryption'] === 'tls' ? 'selected' : '' ?>>STARTTLS / Port 587</option>
              <option value="ssl" <?= $config['smtp_encryption'] === 'ssl' ? 'selected' : '' ?>>SSL/TLS / Port 465</option>
              <option value="none" <?= $config['smtp_encryption'] === 'none' ? 'selected' : '' ?>>Keine</option>
            </select>

            <label>SMTP Benutzer</label>
            <input name="smtp_user" value="<?= h($config['smtp_user']) ?>" autocomplete="username">

            <label>SMTP Passwort</label>
            <input type="password" name="smtp_pass" value="" autocomplete="new-password" placeholder="Leer lassen = gespeichertes Passwort behalten">

            <label>Absender-Mail</label>
            <input name="from_email" value="<?= h($config['from_email']) ?>" placeholder="wiki@example.com">

            <label>Absender-Name</label>
            <input name="from_name" value="<?= h($config['from_name']) ?>">

            <label>Reply-To / Kontakt-Mail</label>
            <input name="reply_to" value="<?= h($config['reply_to']) ?>" placeholder="Optional">
          </section>

          <section class="card">
            <h2>Empfänger</h2>

            <label>Newsletter-Empfänger</label>
            <input name="recipient_email" value="<?= h($config['recipient_email']) ?>" placeholder="ziel@example.com">

            <label>Test-Empfänger</label>
            <input name="test_recipient_email" value="<?= h($config['test_recipient_email']) ?>" placeholder="Optional, sonst Newsletter-Empfänger">

            <label>Abmeldelink</label>
            <input name="unsubscribe_url" value="<?= h($config['unsubscribe_url']) ?>" placeholder="https://example.com/newsletter/abmelden">
            <p class="hint">Optional. Wird im Footer und als <code>List-Unsubscribe</code>-Header eingebunden.</p>
          </section>

          <section class="card">
            <h2>Automatisierung</h2>

            <label>Cron Token</label>
            <input name="cron_token" value="<?= h($config['cron_token']) ?>">
            <p class="hint">CLI-Cronjob:</p>
            <p class="hint"><code>0 8 1 * * /usr/bin/php <?= h(__FILE__) ?> --cron --token='<?= h($config['cron_token']) ?>'</code></p>
            <p class="hint">Web-Cronjob:</p>
            <p class="hint"><code>0 8 1 * * /usr/bin/curl -fsS 'https://deine-domain.tld/wiki-newsletter.php?cron=<?= h($config['cron_token']) ?>' &gt;/dev/null</code></p>
          </section>

          <section class="card full">
            <h2>Aktionen</h2>
            <div class="actions">
              <button type="submit" name="action" value="save">Einstellungen speichern</button>
              <button type="submit" name="action" value="preview" class="light">Vorschau erzeugen</button>
              <button type="submit" name="action" value="test_send" class="secondary">Testnewsletter senden</button>
              <button type="submit" name="action" value="monthly_send" class="warn">Monatsnewsletter jetzt senden</button>
            </div>
            <p class="hint">Der Testnewsletter nutzt die aktuellsten Artikel ohne Monatsfilter. Der Monatsnewsletter nutzt den eingestellten Zeitraum und wird pro Zeitraum nur einmal versendet.</p>
          </section>
        </div>
      </form>

      <?php if ($previewHtml !== ''): ?>
        <section class="card full" style="margin-top:18px;">
          <h2>Vorschau</h2>
          <div class="preview-toolbar">
            <p>In Outlook: „Für Outlook kopieren“ klicken und in eine neue E-Mail einfügen (Strg+V). Der komplette Newsletter wird im Outlook-HTML-Format kopiert.</p>
            <div class="actions" style="margin-top:0;">
              <button type="button" id="copy-outlook-rich" class="light">Für Outlook kopieren</button>
              <button type="button" id="copy-outlook-html" class="secondary">HTML kopieren</button>
            </div>
          </div>
          <iframe class="preview" id="preview-frame" srcdoc="<?= h($previewHtml) ?>"></iframe>
          <textarea class="preview-source" id="preview-html-source" readonly><?= h($previewHtml) ?></textarea>
          <script type="application/json" id="preview-clipboard-fragment"><?= json_encode($previewClipboardHtml, JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_UNESCAPED_UNICODE) ?></script>
          <div class="outlook-copy-buffer" id="outlook-copy-buffer" aria-hidden="true"></div>
          <div class="copy-status" id="copy-status" aria-live="polite"></div>
        </section>
        <script>
          (function () {
            const htmlSource = document.getElementById('preview-html-source');
            const fragmentNode = document.getElementById('preview-clipboard-fragment');
            const copyBuffer = document.getElementById('outlook-copy-buffer');
            const previewFrame = document.getElementById('preview-frame');
            const status = document.getElementById('copy-status');
            const richButton = document.getElementById('copy-outlook-rich');
            const htmlButton = document.getElementById('copy-outlook-html');

            if (!htmlSource || !fragmentNode || !copyBuffer || !status || !richButton || !htmlButton) {
              return;
            }

            let clipboardFragment = '';

            try {
              clipboardFragment = JSON.parse(fragmentNode.textContent || '""');
            } catch (error) {
              clipboardFragment = '';
            }

            function showStatus(message) {
              status.textContent = message;
              window.setTimeout(function () {
                if (status.textContent === message) {
                  status.textContent = '';
                }
              }, 4000);
            }

            function stripHtml(html) {
              const tmp = document.createElement('div');
              tmp.innerHTML = html;
              return (tmp.textContent || tmp.innerText || '').replace(/\s+/g, ' ').trim();
            }

            function buildClipboardHtml(fragment) {
              return (
                '<!doctype html>' +
                '<html lang="de" xmlns="http://www.w3.org/1999/xhtml" ' +
                'xmlns:v="urn:schemas-microsoft-com:vml" ' +
                'xmlns:o="urn:schemas-microsoft-com:office:office">' +
                '<head><meta charset="utf-8">' +
                '<style type="text/css">' +
                'body{margin:0;padding:0;background:#eef2f6;}' +
                'table,td{border-collapse:collapse;mso-table-lspace:0pt;mso-table-rspace:0pt;}' +
                'a{text-decoration:none;}' +
                '</style></head><body>' + fragment + '</body></html>'
              );
            }

            function getFragmentHtml() {
              if (previewFrame && previewFrame.contentDocument && previewFrame.contentDocument.body) {
                return previewFrame.contentDocument.body.innerHTML;
              }

              if (clipboardFragment) {
                return clipboardFragment;
              }

              const fullHtml = htmlSource.value || '';
              const match = fullHtml.match(/<body[^>]*>([\s\S]*)<\/body>/i);
              return match ? match[1] : fullHtml;
            }

            function copyViaClipboardEvent(fragment) {
              copyBuffer.innerHTML = fragment;

              const range = document.createRange();
              range.selectNodeContents(copyBuffer);
              const selection = window.getSelection();
              if (!selection) {
                return false;
              }

              selection.removeAllRanges();
              selection.addRange(range);

              let copied = false;

              function onCopy(event) {
                event.preventDefault();
                event.clipboardData.setData('text/html', buildClipboardHtml(fragment));
                event.clipboardData.setData('text/plain', stripHtml(fragment));
                copied = true;
              }

              document.addEventListener('copy', onCopy);
              copied = document.execCommand('copy');
              document.removeEventListener('copy', onCopy);

              selection.removeAllRanges();
              copyBuffer.innerHTML = '';

              return copied;
            }

            function copyFromPreviewFrame() {
              if (!previewFrame || !previewFrame.contentWindow || !previewFrame.contentDocument) {
                return false;
              }

              const frameDoc = previewFrame.contentDocument;
              const frameWindow = previewFrame.contentWindow;
              const frameSelection = frameWindow.getSelection();
              if (!frameDoc.body || !frameSelection) {
                return false;
              }

              const range = frameDoc.createRange();
              range.selectNodeContents(frameDoc.body);
              frameSelection.removeAllRanges();
              frameSelection.addRange(range);
              frameWindow.focus();

              const copied = frameDoc.execCommand('copy');
              frameSelection.removeAllRanges();

              return copied;
            }

            async function copyForOutlook() {
              const fragment = getFragmentHtml();

              if (!fragment) {
                showStatus('Keine Vorschau zum Kopieren gefunden.');
                return;
              }

              if (copyFromPreviewFrame()) {
                showStatus('Newsletter wurde aus der Vorschau für Outlook kopiert.');
                return;
              }

              if (copyViaClipboardEvent(fragment)) {
                showStatus('Newsletter wurde im Outlook-kompatiblen HTML-Format kopiert.');
                return;
              }

              if (window.ClipboardItem && navigator.clipboard && navigator.clipboard.write) {
                try {
                  await navigator.clipboard.write([
                    new ClipboardItem({
                      'text/html': new Blob([buildClipboardHtml(fragment)], { type: 'text/html' }),
                      'text/plain': new Blob([stripHtml(fragment)], { type: 'text/plain' })
                    })
                  ]);
                  showStatus('Newsletter wurde für Outlook kopiert.');
                  return;
                } catch (error) {
                  // Fallback unten
                }
              }

              htmlSource.value = buildClipboardHtml(fragment);
              htmlSource.style.display = 'block';
              htmlSource.focus();
              htmlSource.select();
              showStatus('Automatisches Kopieren nicht möglich. HTML ist markiert – bitte mit Strg+C kopieren.');
            }

            async function copyText(value, successMessage) {
              try {
                await navigator.clipboard.writeText(value);
                showStatus(successMessage);
              } catch (error) {
                htmlSource.style.display = 'block';
                htmlSource.value = value;
                htmlSource.focus();
                htmlSource.select();
                showStatus('HTML markiert. Bitte mit Strg+C kopieren.');
              }
            }

            richButton.addEventListener('click', copyForOutlook);
            htmlButton.addEventListener('click', function () {
              copyText(htmlSource.value || buildClipboardHtml(getFragmentHtml()), 'HTML-Quelltext wurde kopiert.');
            });
          })();
        </script>
      <?php endif; ?>
    <?php endif; ?>
  </div>
</body>
</html>