<?php
require_once 'config.php';

/**
 * Validate email address
 */
function validateEmail($email) {
    return preg_match(EMAIL_REGEX, $email);
}

/**
 * Sanitize input string
 */
function sanitizeInput($input) {
    return htmlspecialchars(trim($input), ENT_QUOTES, 'UTF-8');
}

/**
 * Generate XML from form data
 */
function generateXML($data) {
    $xml = new DOMDocument('1.0', 'UTF-8');
    $xml->formatOutput = true;
    
    $root = $xml->createElement('form_submission');
    $xml->appendChild($root);
    
    // Static data
    $static = $xml->createElement('static');
    $root->appendChild($static);
    
    foreach (['name', 'lastname', 'title', 'telno', 'mail', 'apparatsname', 'subject', 'semester', 'dauerapparat'] as $field) {
        if (isset($data[$field])) {
            $element = $xml->createElement($field, htmlspecialchars($data[$field]));
            $static->appendChild($element);
        }
    }
    
    if (!empty($data['message'])) {
        $messageEl = $xml->createElement('message', htmlspecialchars($data['message']));
        $static->appendChild($messageEl);
    }
    
    // Books
    if (isset($data['books']) && is_array($data['books'])) {
        $booksNode = $xml->createElement('books');
        $root->appendChild($booksNode);
        
        foreach ($data['books'] as $book) {
            $bookNode = $xml->createElement('book');
            $booksNode->appendChild($bookNode);
            
            foreach (['authorname', 'year', 'title', 'signature'] as $field) {
                $value = isset($book[$field]) ? htmlspecialchars($book[$field]) : '';
                $fieldNode = $xml->createElement($field, $value);
                $bookNode->appendChild($fieldNode);
            }
        }
    }
    
    return $xml->saveXML();
}

/**
 * Generate XML for ELSA form
 */
function generateELSAXML($data) {
    $xml = new DOMDocument('1.0', 'UTF-8');
    $xml->formatOutput = true;
    
    $root = $xml->createElement('elsa_submission');
    $xml->appendChild($root);
    
    // General info
    $generalInfo = $xml->createElement('general_info');
    $root->appendChild($generalInfo);
    
    $generalFields = ['name', 'lastname', 'title', 'mail', 'subject', 'classname', 
                      'usage_date_from', 'usage_date_to', 'availability_date'];
    
    foreach ($generalFields as $field) {
        if (isset($data[$field])) {
            $element = $xml->createElement($field, htmlspecialchars($data[$field]));
            $generalInfo->appendChild($element);
        }
    }
    
    if (!empty($data['message'])) {
        $messageEl = $xml->createElement('message', htmlspecialchars($data['message']));
        $generalInfo->appendChild($messageEl);
    }
    
    // Media sections
    $mediaRoot = $xml->createElement('media');
    $root->appendChild($mediaRoot);
    
    // Add different media types (monografie, zeitschrift, herausgeber)
    $mediaTypes = [
        'monografien' => $data['monografien'] ?? [],
        'zeitschriftenartikel' => $data['zeitschriftenartikel'] ?? [],
        'herausgeberwerke' => $data['herausgeberwerke'] ?? []
    ];
    
    foreach ($mediaTypes as $type => $entries) {
        if (!empty($entries)) {
            $section = $xml->createElement($type);
            $mediaRoot->appendChild($section);
            
            foreach ($entries as $entry) {
                $entryNode = $xml->createElement('entry');
                $section->appendChild($entryNode);
                
                foreach ($entry as $key => $value) {
                    $fieldNode = $xml->createElement($key, htmlspecialchars($value));
                    $entryNode->appendChild($fieldNode);
                }
            }
        }
    }
    
    return $xml->saveXML();
}

/**
 * Send email with XML attachment
 * Uses PHP's mail() function or SMTP if configured
 */
function sendEmail($subject, $xmlContent, $toEmail = null) {
    $to = $toEmail ?? MAIL_TO;
    $from = MAIL_FROM;
    
    if (!MAIL_ENABLED) {
        // Log instead of sending
        error_log("==========================================================");
        error_log("MAIL SENDING DISABLED - Would have sent:");
        error_log("From: " . $from);
        error_log("To: " . $to);
        error_log("Subject: " . $subject);
        error_log("----------------------------------------------------------");
        error_log($xmlContent);
        error_log("==========================================================");
        return true;
    }
    
    // Try using SMTP if credentials are configured
    if (SMTP_USERNAME && SMTP_PASSWORD && class_exists('PHPMailer\PHPMailer\PHPMailer')) {
        return sendEmailSMTP($subject, $xmlContent, $to, $from);
    }
    
    // Fallback to PHP mail()
    $headers = "From: " . $from . "\r\n";
    $headers .= "Content-Type: application/xml; charset=UTF-8\r\n";
    $headers .= "X-Mailer: PHP/" . phpversion();
    
    return mail($to, $subject, $xmlContent, $headers);
}

/**
 * Send email via SMTP using PHPMailer (if available)
 */
function sendEmailSMTP($subject, $xmlContent, $to, $from) {
    if (!class_exists('PHPMailer\PHPMailer\PHPMailer')) {
        error_log("PHPMailer not available, falling back to mail()");
        return false;
    }
    
    $mail = new PHPMailer\PHPMailer\PHPMailer(true);
    
    try {
        // Server settings
        $mail->isSMTP();
        $mail->Host = SMTP_HOST;
        $mail->SMTPAuth = true;
        $mail->Username = SMTP_USERNAME;
        $mail->Password = SMTP_PASSWORD;
        $mail->SMTPSecure = SMTP_ENCRYPTION;
        $mail->Port = SMTP_PORT;
        $mail->CharSet = 'UTF-8';
        
        // Recipients
        $mail->setFrom($from);
        $mail->addAddress($to);
        
        // Content
        $mail->Subject = $subject;
        $mail->Body = $xmlContent;
        $mail->ContentType = 'application/xml';
        
        $mail->send();
        return true;
    } catch (Exception $e) {
        error_log("Email sending failed: " . $mail->ErrorInfo);
        return false;
    }
}

/**
 * Redirect to URL
 */
function redirect($url) {
    header("Location: " . $url);
    exit;
}

/**
 * Get POST value with default
 */
function post($key, $default = '') {
    return isset($_POST[$key]) ? sanitizeInput($_POST[$key]) : $default;
}

/**
 * Get all POST values matching a pattern (for arrays)
 */
function postArray($key) {
    return isset($_POST[$key]) && is_array($_POST[$key]) ? 
           array_map('sanitizeInput', $_POST[$key]) : [];
}