/**
 * Log activity for audit trail
 */
function logActivity($activity_type, $description, $reference_id = null, $user_id = null) {
    require_once 'config/database.php';
    
    try {
        $pdo = getDBConnection();
        if ($pdo) {
            $stmt = $pdo->prepare("
                INSERT INTO activity_logs (activity_type, description, user_id, reference_id, ip_address, user_agent) 
                VALUES (?, ?, ?, ?, ?, ?)
            ");
            
            $user_id = $user_id ?: ($_SESSION['user_id'] ?? null);
            $ip_address = $_SERVER['REMOTE_ADDR'] ?? null;
            $user_agent = $_SERVER['HTTP_USER_AGENT'] ?? null;
            
            return $stmt->execute([
                $activity_type,
                $description,
                $user_id,
                $reference_id,
                $ip_address,
                $user_agent
            ]);
        }
    } catch (Exception $e) {
        error_log("Error logging activity: " . $e->getMessage());
    }
    
    return false;
}

/**
 * Send SMS using SmartSMS API
 */
function sendSMS($phone, $message, $sender_id = null) {
    $api_key = getSiteSetting('smartsms_api_key');
    $default_sender = getSiteSetting('smartsms_sender_id', 'BCBC');
    
    if (empty($api_key)) {
        return ['success' => false, 'message' => 'SMS API not configured'];
    }
    
    $sender_id = $sender_id ?: $default_sender;
    
    $url = 'https://smartsmssolutions.com/api/json.php';
    $data = [
        'username' => $api_key,
        'password' => '', // SmartSMS uses API key as username
        'message' => $message,
        'sender' => $sender_id,
        'mobiles' => $phone
    ];
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    
    $response = curl_exec($ch);
    $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);
    
    if ($http_code == 200) {
        $result = json_decode($response, true);
        return [
            'success' => true,
            'message' => 'SMS sent successfully',
            'response' => $result
        ];
    } else {
        return [
            'success' => false,
            'message' => 'Failed to send SMS',
            'response' => $response
        ];
    }
}

/**
 * Send bulk SMS to multiple recipients
 */
function sendBulkSMS($recipients, $message, $sender_id = null) {
    $results = [];
    
    foreach ($recipients as $phone) {
        $result = sendSMS($phone, $message, $sender_id);
        $results[] = [
            'phone' => $phone,
            'success' => $result['success'],
            'message' => $result['message']
        ];
        
        // Add small delay to avoid rate limiting
        usleep(100000); // 0.1 second delay
    }
    
    return $results;
}

/**
 * Get members by department
 */
function getMembersByDepartment($department = null) {
    require_once 'config/database.php';
    
    try {
        $pdo = getDBConnection();
        if ($pdo) {
            if ($department) {
                $stmt = $pdo->prepare("SELECT * FROM members WHERE department = ? AND status = 'active' ORDER BY first_name, last_name");
                $stmt->execute([$department]);
            } else {
                $stmt = $pdo->prepare("SELECT * FROM members WHERE status = 'active' ORDER BY first_name, last_name");
                $stmt->execute();
            }
            
            return $stmt->fetchAll();
        }
    } catch (Exception $e) {
        error_log("Error getting members: " . $e->getMessage());
    }
    
    return [];
}

/**
 * Process Paystack payment
 */
function processPaystackPayment($amount, $email, $reference = null) {
    $public_key = getSiteSetting('paystack_public_key');
    $secret_key = getSiteSetting('paystack_secret_key');
    
    if (empty($secret_key)) {
        return ['success' => false, 'message' => 'Paystack not configured'];
    }
    
    $reference = $reference ?: 'BCBC_' . time() . '_' . rand(1000, 9999);
    
    $url = 'https://api.paystack.co/transaction/initialize';
    $data = [
        'amount' => $amount * 100, // Convert to kobo
        'email' => $email,
        'reference' => $reference,
        'callback_url' => getSiteSetting('site_url', 'http://localhost') . '/payment-callback.php'
    ];
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Authorization: Bearer ' . $secret_key,
        'Content-Type: application/json'
    ]);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    
    $response = curl_exec($ch);
    $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);
    
    if ($http_code == 200) {
        $result = json_decode($response, true);
        if ($result['status']) {
            return [
                'success' => true,
                'authorization_url' => $result['data']['authorization_url'],
                'reference' => $result['data']['reference']
            ];
        }
    }
    
    return ['success' => false, 'message' => 'Payment initialization failed'];
}

/**
 * Verify Paystack payment
 */
function verifyPaystackPayment($reference) {
    $secret_key = getSiteSetting('paystack_secret_key');
    
    if (empty($secret_key)) {
        return ['success' => false, 'message' => 'Paystack not configured'];
    }
    
    $url = 'https://api.paystack.co/transaction/verify/' . $reference;
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, [
        'Authorization: Bearer ' . $secret_key
    ]);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    
    $response = curl_exec($ch);
    $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);
    
    if ($http_code == 200) {
        $result = json_decode($response, true);
        if ($result['status'] && $result['data']['status'] === 'success') {
            return [
                'success' => true,
                'amount' => $result['data']['amount'] / 100, // Convert from kobo
                'customer' => $result['data']['customer'],
                'paid_at' => $result['data']['paid_at']
            ];
        }
    }
    
    return ['success' => false, 'message' => 'Payment verification failed'];
}

/**
 * Send welcome email to new members
 */
function sendWelcomeEmail($email, $name) {
    $subject = 'Welcome to Better City Bible Church!';
    $message = "
    <html>
    <body>
        <h2>Welcome to Better City Bible Church, {$name}!</h2>
        <p>We are thrilled to have you join our church family. Your registration has been successfully completed.</p>
        
        <h3>What's Next?</h3>
        <ul>
            <li>Join us for Sunday worship at 9:00 AM or 11:00 AM</li>
            <li>Attend our Wednesday evening Bible study at 7:00 PM</li>
            <li>Connect with a ministry that interests you</li>
            <li>Meet our pastoral team and other members</li>
        </ul>
        
        <p>Our church is located at:<br>
        Behind New Model Int'l College<br>
        Opposite Ologede Police Station<br>
        Off Ikere Road, Ado-Ekiti</p>
        
        <p>If you have any questions, please don't hesitate to contact us.</p>
        
        <p>Blessings,<br>
        Rev. Dr. & Lady Evang. Olusegun Akinloose<br>
        Lead Pastor & General Overseer<br>
        Better City Bible Church</p>
    </body>
    </html>
    ";
    
    return sendEmail($email, $subject, $message);
}

/**
 * Send volunteer confirmation email
 */
function sendVolunteerConfirmationEmail($email, $name) {
    $subject = 'Thank You for Your Volunteer Application!';
    $message = "
    <html>
    <body>
        <h2>Thank You, {$name}!</h2>
        <p>We have received your volunteer application and are excited about your desire to serve with us at Better City Bible Church.</p>
        
        <p>Our volunteer coordinator will review your application and contact you within the next few days to discuss next steps and available opportunities.</p>
        
        <p>Thank you for your heart to serve God and our community!</p>
        
        <p>Blessings,<br>
        Better City Bible Church<br>
        Volunteer Ministry Team</p>
    </body>
    </html>
    ";
    
    return sendEmail($email, $subject, $message);
}

/**
 * Send testimony confirmation email
 */
function sendTestimonyConfirmationEmail($email, $name, $title) {
    $subject = 'Thank You for Sharing Your Testimony!';
    $message = "
    <html>
    <body>
        <h2>Thank You, {$name}!</h2>
        <p>We have received your testimony titled \"{$title}\" and are blessed by how God has worked in your life.</p>
        
        <p>Our team will review your testimony, and if you gave permission for publication, it may be featured on our website or in our church communications to encourage others.</p>
        
        <p>Thank you for sharing how God has moved in your life!</p>
        
        <p>Blessings,<br>
        Better City Bible Church<br>
        Ministry Team</p>
    </body>
    </html>
    ";
    
    return sendEmail($email, $subject, $message);
}

/**
 * Send appointment confirmation email
 */
function sendAppointmentConfirmationEmail($email, $name, $date, $time) {
    $subject = 'Counseling Appointment Request Received';
    $message = "
    <html>
    <body>
        <h2>Dear {$name},</h2>
        <p>We have received your request for a counseling appointment.</p>
        
        <p><strong>Requested Date:</strong> " . formatDate($date) . "<br>
        <strong>Requested Time:</strong> {$time}</p>
        
        <p>Our pastoral team will review your request and contact you within 24-48 hours to confirm the appointment details.</p>
        
        <p>We are here to support you and look forward to meeting with you.</p>
        
        <p>Blessings,<br>
        Rev. Dr. & Lady Evang. Olusegun Akinloose<br>
        Better City Bible Church</p>
    </body>
    </html>
    ";
    
    return sendEmail($email, $subject, $message);
}

/**
 * Send urgent appointment notification to admin
 */
function sendUrgentAppointmentNotification($appointment_id, $name, $type) {
    $admin_email = getSiteSetting('church_email', 'admin@bettercitybiblechurch.org');
    $subject = 'URGENT: Counseling Appointment Request';
    $message = "
    <html>
    <body>
        <h2>URGENT Counseling Appointment Request</h2>
        <p>A new urgent counseling appointment request has been submitted:</p>
        
        <p><strong>Name:</strong> {$name}<br>
        <strong>Type:</strong> {$type}<br>
        <strong>Appointment ID:</strong> {$appointment_id}</p>
        
        <p>Please review and respond to this request as soon as possible.</p>
        
        <p><a href=\"" . getSiteSetting('site_url', 'http://localhost') . "/admin/counseling.php?id={$appointment_id}\">View Appointment Details</a></p>
    </body>
    </html>
    ";
    
    return sendEmail($admin_email, $subject, $message);
}

/**
 * Generate random password
 */
function generateRandomPassword($length = 12) {
    $characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*';
    $password = '';
    
    for ($i = 0; $i < $length; $i++) {
        $password .= $characters[rand(0, strlen($characters) - 1)];
    }
    
    return $password;
}

/**
 * Export data to CSV
 */
function exportToCSV($data, $filename, $headers = []) {
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="' . $filename . '"');
    
    $output = fopen('php://output', 'w');
    
    if (!empty($headers)) {
        fputcsv($output, $headers);
    } elseif (!empty($data)) {
        fputcsv($output, array_keys($data[0]));
    }
    
    foreach ($data as $row) {
        fputcsv($output, $row);
    }
    
    fclose($output);
    exit();
}

/**
 * Import CSV data
 */
function importFromCSV($file_path, $skip_header = true) {
    $data = [];
    
    if (($handle = fopen($file_path, 'r')) !== FALSE) {
        $row_count = 0;
        
        while (($row = fgetcsv($handle, 1000, ',')) !== FALSE) {
            if ($skip_header && $row_count == 0) {
                $row_count++;
                continue;
            }
            
            $data[] = $row;
            $row_count++;
        }
        
        fclose($handle);
    }
    
    return $data;
}