<?php
session_start();
require_once 'db/config.php';
require_once 'mail/MailService.php';
require_once 'includes/webinar_schedule.php';

header('Content-Type: application/json');

function normalize_email_address($email) {
    return strtolower(trim((string) $email));
}

function has_valid_email_dns($domain) {
    if ($domain === '') {
        return false;
    }

    return checkdnsrr($domain, 'MX') || checkdnsrr($domain, 'A') || checkdnsrr($domain, 'AAAA');
}

function is_disposable_email_domain($domain) {
    static $blocked_domains = [
        '10minutemail.com',
        'dispostable.com',
        'emailondeck.com',
        'fakeinbox.com',
        'guerrillamail.com',
        'maildrop.cc',
        'mailinator.com',
        'mailnesia.com',
        'mintemail.com',
        'sharklasers.com',
        'tempmail.com',
        'temp-mail.org',
        'trashmail.com',
        'yopmail.com',
        'example.com',
        'example.net',
        'example.org',
    ];

    return in_array($domain, $blocked_domains, true);
}

function validate_registration_email($email) {
    $email = normalize_email_address($email);

    if ($email === '' || !filter_var($email, FILTER_VALIDATE_EMAIL)) {
        return 'Please enter a valid email address.';
    }

    if (strlen($email) > 190) {
        return 'Please enter a shorter email address.';
    }

    $parts = explode('@', $email);
    if (count($parts) !== 2) {
        return 'Please enter a valid email address.';
    }

    [$local, $domain] = $parts;

    if ($local === '' || $domain === '') {
        return 'Please enter a valid email address.';
    }

    if (is_disposable_email_domain($domain)) {
        return 'Please use your real email address. Temporary or disposable inboxes are not allowed.';
    }

    if (!has_valid_email_dns($domain)) {
        return 'Please use an email with a real mail domain.';
    }

    return null;
}

function clean_text_input($value, int $max_length = 255): string {
    $value = trim((string) $value);
    $value = strip_tags($value);
    $value = preg_replace('/[ -]/u', '', $value) ?? '';

    if (function_exists('mb_substr')) {
        return mb_substr($value, 0, $max_length);
    }

    return substr($value, 0, $max_length);
}

function normalize_timezone_input($value): ?string {
    $timezone = clean_text_input($value, 100);

    if ($timezone === '') {
        return null;
    }

    return in_array($timezone, timezone_identifiers_list(), true) ? $timezone : null;
}

// --- Helper function to fetch webinar details ---
function get_webinar_details($id) {
    if (empty($id)) return null;
    try {
        $stmt = db()->prepare("SELECT id, title, description, scheduled_at, presenter FROM webinars WHERE id = ?");
        $stmt->execute([$id]);
        return $stmt->fetch(PDO::FETCH_ASSOC);
    } catch (PDOException $e) {
        error_log("Database error fetching webinar ID $id: " . $e->getMessage());
        return null;
    }
}

// --- Only allow POST requests ---
if ($_SERVER["REQUEST_METHOD"] !== "POST") {
    echo json_encode(['success' => false, 'error' => 'Invalid request method.']);
    exit;
}

$webinar_id = filter_input(INPUT_POST, 'webinar_id', FILTER_VALIDATE_INT) ?: 1;
$webinar = get_webinar_details($webinar_id);

if (!$webinar) {
    http_response_code(404);
    echo json_encode(['success' => false, 'error' => 'Webinar not found.']);
    exit;
}

// --- DATA CAPTURE ---
$email_input = (string) filter_input(INPUT_POST, 'email', FILTER_UNSAFE_RAW);
$email = normalize_email_address($email_input);
$email_error = validate_registration_email($email);
$first_name = clean_text_input(filter_input(INPUT_POST, 'first_name', FILTER_UNSAFE_RAW), 120);
$last_name = clean_text_input(filter_input(INPUT_POST, 'last_name', FILTER_UNSAFE_RAW), 120);
$company = clean_text_input(filter_input(INPUT_POST, 'company', FILTER_UNSAFE_RAW), 180);
$how_did_you_hear = clean_text_input(filter_input(INPUT_POST, 'how_did_you_hear', FILTER_UNSAFE_RAW), 120);
$timezone = normalize_timezone_input(filter_input(INPUT_POST, 'timezone', FILTER_UNSAFE_RAW));

$allowed_sources = [
    'Social Media',
    'LinkedIn',
    'Reddit',
    'Threads',
    'Advertisement',
    'ChatGPT',
    'Flatlogic Community Discord',
    'Other',
];

// --- VALIDATION ---
if (!$first_name || !$last_name || $email === '' || $how_did_you_hear === '') {
    echo json_encode(['success' => false, 'error' => 'Please fill out all required fields.']);
    exit;
}

if ($email_error !== null) {
    echo json_encode(['success' => false, 'error' => $email_error]);
    exit;
}

if (!in_array($how_did_you_hear, $allowed_sources, true)) {
    echo json_encode(['success' => false, 'error' => 'Please choose how you heard about this webinar from the list.']);
    exit;
}

try {
    // --- CHECK IF ALREADY REGISTERED OR SOFT-DELETED -- - 
    $stmt = db()->prepare("SELECT id, deleted_at FROM attendees WHERE webinar_id = ? AND email = ?");
    $stmt->execute([$webinar_id, $email]);
    $existing_user = $stmt->fetch(PDO::FETCH_ASSOC);

    $send_email = false;

    if ($existing_user) {
        if ($existing_user['deleted_at'] !== null) {
            // --- USER IS SOFT-DELETED, SO REACTIVATE AND UPDATE ---
            $sql = "UPDATE attendees SET first_name = ?, last_name = ?, company = ?, how_did_you_hear = ?, timezone = ?, deleted_at = NULL, created_at = NOW(), consented = 1 WHERE id = ?";
            $stmt = db()->prepare($sql);
            $stmt->execute([$first_name, $last_name, $company, $how_did_you_hear, $timezone, $existing_user['id']]);
            $send_email = true;
        } else {
            // --- USER IS ACTIVE, SO REJECT ---
            echo json_encode(['success' => false, 'error' => 'You are already registered for this webinar.']);
            exit;
        }
    } else {
        // --- REGISTER NEW USER ---
        $password_hash = password_hash($email . time(), PASSWORD_DEFAULT);
        $sql = "INSERT INTO attendees (webinar_id, first_name, last_name, email, company, how_did_you_hear, password, timezone, consented) 
                VALUES (?, ?, ?, ?, ?, ?, ?, ?, 1)";
        $stmt = db()->prepare($sql);
        $stmt->execute([$webinar_id, $first_name, $last_name, $email, $company, $how_did_you_hear, $password_hash, $timezone]);
        $send_email = true;
    }
    
    $schedule = webinar_schedule_data($webinar);
    $event_title = $schedule['title'];
    $event_description = $schedule['calendar_description'];
    $start_time_utc = webinar_utc_stamp($schedule['start']);
    $end_time_utc = webinar_utc_stamp($schedule['end']);

    $google_link = 'https://www.google.com/calendar/render?action=TEMPLATE' .
        '&text=' . urlencode($event_title) .
        '&dates=' . $start_time_utc . '/' . $end_time_utc .
        '&details=' . urlencode($event_description) .
        '&location=' . urlencode('Online') .
        '&ctz=UTC';

    if ($send_email) {
        // --- SEND CONFIRMATION EMAIL ---
        $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') ? 'https' : 'http';
        $host = $_SERVER['HTTP_HOST'];
        $logo_url = $protocol . '://' . $host . '/assets/pasted-20251030-095744-1b7c02ab.png';
        $subject = "Confirmation: You're Registered for {$event_title}";
        $safe_first_name = htmlspecialchars($first_name, ENT_QUOTES, 'UTF-8');
        $safe_title = htmlspecialchars($event_title, ENT_QUOTES, 'UTF-8');
        $safe_date_long = htmlspecialchars($schedule['date_long'], ENT_QUOTES, 'UTF-8');
        $safe_berlin_label = htmlspecialchars($schedule['berlin_label'], ENT_QUOTES, 'UTF-8');
        $safe_new_york_label = htmlspecialchars($schedule['new_york_label'], ENT_QUOTES, 'UTF-8');
        $safe_los_angeles_label = htmlspecialchars($schedule['los_angeles_label'], ENT_QUOTES, 'UTF-8');

        $body_html = <<<HTML
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Webinar Registration Confirmation</title>
</head>
<body style="font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif; background-color: #f4f4f4; color: #333; margin: 0; padding: 0;">
    <table width="100%" border="0" cellspacing="0" cellpadding="0" style="background-color: #f4f4f4;">
        <tr>
            <td align="center">
                <table width="600" border="0" cellspacing="0" cellpadding="0" style="background-color: #ffffff; margin: 20px auto; border-radius: 10px; box-shadow: 0 4px 8px rgba(0,0,0,0.1);">
                    <tr>
                        <td align="center" style="padding: 40px 20px; background: linear-gradient(135deg, #1a237e 0%, #673ab7 100%); border-radius: 10px 10px 0 0;">
                            <img src="{$logo_url}" alt="AppWizzy Logo" style="height: 60px; margin-bottom: 20px;">
                            <h1 style="color: #ffffff; font-size: 28px; margin: 0; line-height: 1.2;">You're Registered!</h1>
                        </td>
                    </tr>
                    <tr>
                        <td style="padding: 40px 30px;">
                            <h2 style="font-size: 22px; color: #1a237e;">Hello {$safe_first_name},</h2>
                            <p style="font-size: 16px; line-height: 1.6;">Thank you for registering for the <strong>{$safe_title}</strong> webinar.</p>
                            <p style="font-size: 16px; line-height: 1.6;">We're excited to have you join us for this professional vibe-coding session.</p>
                            <div style="background-color: #f9f9f9; border-left: 4px solid #673ab7; padding: 15px 20px; margin: 20px 0;">
                                <p style="margin: 0; font-size: 16px;"><strong>Webinar Details:</strong></p>
                                <p style="margin: 10px 0 0; font-size: 16px;">{$safe_date_long} | <strong>{$safe_berlin_label}</strong> | {$safe_new_york_label} | {$safe_los_angeles_label}</p>
                            </div>
                            <p style="font-size: 16px; line-height: 1.6;">You'll learn the fastest way to go from an idea to a working app you own, running on your server, with your database, using real frameworks.</p>
                            <p style="font-size: 16px; line-height: 1.6;"><strong>Your personal webinar access link will be emailed to you 1 day before the event.</strong></p>
                            <p style="text-align: center; margin-top: 30px;">
                                <a href="{$google_link}" style="background: linear-gradient(135deg, #3f51b5 0%, #9c27b0 100%); color: #ffffff; padding: 12px 25px; text-decoration: none; border-radius: 8px; font-weight: bold;">Add to Calendar</a>
                            </p>
                        </td>
                    </tr>
                    <tr>
                        <td align="center" style="padding: 20px; background-color: #f4f4f4; border-top: 1px solid #dddddd;">
                            <p style="margin: 0; color: #777;">&copy; 2025 AppWizzy. All rights reserved.</p>
                            <p style="margin: 5px 0 0; color: #777;">You can <a href="{$protocol}://{$host}/" style="color: #3f51b5;">visit our website</a> for more information.</p>
                        </td>
                    </tr>
                </table>
            </td>
        </tr>
    </table>
</body>
</html>
HTML;
        MailService::sendMail($email, $subject, $body_html);
    }

    $ics_content = implode("\r\n", [
        'BEGIN:VCALENDAR',
        'VERSION:2.0',
        'PRODID:-//Flatlogic//' . $event_title . '//EN',
        'BEGIN:VEVENT',
        'URL:' . 'http://' . $_SERVER['HTTP_HOST'],
        'DTSTART:' . $start_time_utc,
        'DTEND:' . $end_time_utc,
        'SUMMARY:' . $event_title,
        'DESCRIPTION:' . str_replace(PHP_EOL, '\\n', $event_description),
        'LOCATION:Online',
        'END:VEVENT',
        'END:VCALENDAR'
    ]);
    $outlook_link = 'data:text/calendar;charset=utf-8,' . rawurlencode($ics_content);

    echo json_encode([
        'success' => true,
        'webinar_title' => $event_title . '<br><small><strong>Professional Vibe-Coding Webinar</strong></small>',
        'google_link' => $google_link,
        'outlook_link' => $outlook_link,
        'schedule_line' => $schedule['timezone_line']
    ]);

} 
 catch (Exception $e) {
    http_response_code(500);
    echo json_encode(['success' => false, 'error' => 'An unexpected server error occurred. Please try again.']);
}