<?php if (! defined('BASEPATH')) exit('No direct script access allowed');

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

class Phpmailer_lib
{
    private $CI;
    private $mailer;
    private $smtp_config;
    private $default_settings;

    public function __construct()
    {
        $this->CI = &get_instance();
        // Load SMTP configuration
        $this->load_smtp_config();

        // Initialize PHPMailer
        $this->init_phpmailer();
    }

    private function load_smtp_config()
    {
        $this->CI->load->config('email');
        $config = $this->CI->config->item('smtp_settings');
        // Default settings
        $this->default_settings = [
            'smtp_host' =>  $config['host'] ?? 'smtp.mailgun.org',
            'smtp_port' => $config['port'] ?? 465,
            'smtp_username' => $config['username'] ?? 'postmaster@mg.laciasmara.com',
            'smtp_password' => $config['password'],
            'smtp_encryption' => $config['encryption'],
            'from_name' => $config['from_name'],
            'from_email' => $config['from_email'],
            'emails_per_hour' => $config['emails_per_hour']
        ];

        $this->smtp_config = $this->default_settings;
    }

    private function init_phpmailer()
    {
        require_once APPPATH . 'third_party/phpmailer/src/Exception.php';
        require_once APPPATH . 'third_party/phpmailer/src/PHPMailer.php';
        require_once APPPATH . 'third_party/phpmailer/src/SMTP.php';

        $this->mailer = new PHPMailer(true);

        try {
            // Server settings
            $this->mailer->isSMTP();
            $this->mailer->Host = $this->smtp_config['smtp_host'];
            $this->mailer->SMTPAuth = !empty($this->smtp_config['smtp_username']);
            $this->mailer->Username = $this->smtp_config['smtp_username'];
            $this->mailer->Password = $this->smtp_config['smtp_password'];

            // Encryption
            if ($this->smtp_config['smtp_encryption'] === 'ssl') {
                $this->mailer->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
            } elseif ($this->smtp_config['smtp_encryption'] === 'tls') {
                $this->mailer->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
            }

            $this->mailer->Port = (int)$this->smtp_config['smtp_port'];

            // Default sender
            $this->mailer->setFrom(
                $this->smtp_config['from_email'],
                $this->smtp_config['from_name']
            );

            // Additional settings
            $this->mailer->isHTML(true);
            $this->mailer->CharSet = 'UTF-8';
        } catch (Exception $e) {
            log_message('error', 'PHPMailer initialization failed: ' . $e->getMessage());
            throw new Exception('Email configuration error: ' . $e->getMessage());
        }
    }

    /**
     * Send single email
     * 
     * @param array $email_data Array containing email details
     * @return array Result with status and message
     */
    public function send_single($email_data)
    {
        try {
            // Validate required fields
            $required = ['to_email', 'subject', 'body'];
            foreach ($required as $field) {
                if (empty($email_data[$field])) {
                    throw new Exception("Missing required field: $field");
                }
            }

            // Clear previous recipients
            $this->mailer->clearAddresses();
            $this->mailer->clearAttachments();
            $this->mailer->clearCustomHeaders();

            // Set sender (override default if provided)
            if (!empty($email_data['from_email'])) {
                $this->mailer->setFrom(
                    $email_data['from_email'],
                    $email_data['from_name'] ?? $this->smtp_config['from_name']
                );
            }
            if (!$this->validate_email($email_data['to_email'])) {
                throw new Exception("Invalid email address: " . $email_data['to_email']);
            }

            // Set recipient
            $this->mailer->addAddress($email_data['to_email'], $email_data['to_name'] ?? '');

            // Set reply-to
            if (!empty($email_data['reply_to'])) {
                $this->mailer->addReplyTo($email_data['reply_to']);
            }

            // Set subject and body
            $this->mailer->Subject = $email_data['subject'];
            $this->mailer->Body = $email_data['body'];

            // Set plain text alternative if provided
            if (!empty($email_data['alt_body'])) {
                $this->mailer->AltBody = $email_data['alt_body'];
            }

            // Add tracking pixel if tracking_id provided
            if (!empty($email_data['tracking_id'])) {
                $this->mailer->Body = $this->add_tracking_pixel($email_data['body'], $email_data['tracking_id']);
            }

            // Process click tracking links
            if (!empty($email_data['tracking_id'])) {
                $this->mailer->Body = $this->process_tracking_links($this->mailer->Body, $email_data['tracking_id']);
            }

            // Send email
            $sent = $this->mailer->send();

            if ($sent) {
                return [
                    'status' => 'success',
                    'message' => 'Email sent successfully'
                ];
            } else {
                return [
                    'status' => 'failed',
                    'message' => 'Failed to send email'
                ];
            }
        } catch (Exception $e) {
            log_message('error', 'Email sending failed: ' . $e->getMessage());

            return [
                'status' => 'failed',
                'message' => $e->getMessage()
            ];
        }
    }

    /**
     * Send bulk emails with rate limiting
     * 
     * @param int $campaign_id Campaign ID
     * @param array $recipients Array of recipients
     * @param string $template_content Email template content
     * @param array $campaign_data Campaign data (subject, from, etc)
     * @return array Summary of sending results
     */
    public function send_bulk($campaign_id, $recipients, $template_content, $campaign_data)
    {
        $results = [
            'total' => count($recipients),
            'sent' => 0,
            'failed' => 0,
            'errors' => []
        ];

        // Rate limiting
        $emails_per_hour = (int)$this->smtp_config['emails_per_hour'];
        $delay_seconds = 3600 / $emails_per_hour; // Delay between emails

        foreach ($recipients as $recipient) {
            try {
                // Process template with recipient data
                $personalized_content = $this->process_template($template_content, $recipient);
                $personalized_subject = $this->process_template($campaign_data['subject'], $recipient);

                // Generate tracking ID
                $tracking_id = $this->generate_tracking_id($campaign_id, $recipient['id']);

                // Prepare email data
                $email_data = [
                    'to_email' => $recipient['email'],
                    'to_name' => trim(($recipient['first_name'] ?? '') . ' ' . ($recipient['last_name'] ?? '')),
                    'subject' => $personalized_subject,
                    'body' => $personalized_content,
                    'from_email' => $campaign_data['from_email'],
                    'from_name' => $campaign_data['from_name'],
                    'reply_to' => $campaign_data['reply_to'] ?? null,
                    'tracking_id' => $tracking_id
                ];

                // Send email
                $result = $this->send_single($email_data);

                // Log result
                $log_status = $result['status'] === 'success' ? 'sent' : 'failed';
                $this->CI->Campaign_email_log_m->insert([
                    'campaign_id' => $campaign_id,
                    'subscriber_id' => $recipient['id'],
                    'email' => $recipient['email'],
                    'status' => $log_status,
                    'error_message' => $result['status'] === 'failed' ? $result['message'] : null,
                    'tracking_id' => $tracking_id,
                    'sent_at' => $result['status'] === 'success' ? date('Y-m-d H:i:s') : null
                ]);

                if ($result['status'] === 'success') {
                    $results['sent']++;
                } else {
                    $results['failed']++;
                    $results['errors'][] = $recipient['email'] . ': ' . $result['message'];
                }

                // Rate limiting delay
                if ($delay_seconds > 0) {
                    usleep($delay_seconds * 1000000);
                }
            } catch (Exception $e) {
                $results['failed']++;
                $results['errors'][] = $recipient['email'] . ': ' . $e->getMessage();

                log_message('error', 'Bulk email error for ' . $recipient['email'] . ': ' . $e->getMessage());
            }
        }

        return $results;
    }

    /**
     * Process template variables ({{variable}} replacement)
     * 
     * @param string $template Template content
     * @param array $data Data for replacement
     * @return string Processed template
     */
    private function process_template($template, $data)
    {
        // Default variables
        $variables = [
            'first_name' => $data['first_name'] ?? '',
            'last_name' => $data['last_name'] ?? '',
            'email' => $data['email'] ?? '',
            'full_name' => trim(($data['first_name'] ?? '') . ' ' . ($data['last_name'] ?? '')),
            'current_date' => date('Y-m-d'),
            'current_year' => date('Y')
        ];

        // Merge with additional data
        $variables = array_merge($variables, $data);

        // Replace {{variable}} with actual values
        foreach ($variables as $key => $value) {
            $template = str_replace('{{' . $key . '}}', $value, $template);
        }

        // Remove unreplaced variables
        $template = preg_replace('/\{\{[^}]+\}\}/', '', $template);

        return $template;
    }

    // Helper
    /**
     * Add tracking pixel to email content
     */
    private function add_tracking_pixel($content, $tracking_id)
    {
        $tracking_url = site_url('track/open/' . $tracking_id);
        $tracking_pixel = '<img src="' . $tracking_url . '" width="1" height="1" border="0" style="display:none;" alt="">';

        // Add pixel before closing body tag
        if (stripos($content, '</body>') !== false) {
            $content = str_ireplace('</body>', $tracking_pixel . '</body>', $content);
        } else {
            $content .= $tracking_pixel;
        }

        return $content;
    }

    /**
     * Process links for click tracking
     */
    private function process_tracking_links($content, $tracking_id)
    {
        // Find all links and replace with tracking links
        $pattern = '/<a\s+[^>]*href=["\'](https?:\/\/[^"\']+)["\']/i';

        return preg_replace_callback($pattern, function ($matches) use ($tracking_id) {
            $original_url = $matches[1];
            $tracking_url = site_url('track/click/' . $tracking_id . '?url=' . urlencode($original_url));

            return str_replace($original_url, $tracking_url, $matches[0]);
        }, $content);
    }

    /**
     * Generate unique tracking ID
     */
    private function generate_tracking_id($campaign_id, $subscriber_id)
    {
        return md5($campaign_id . '_' . $subscriber_id . '_' . time() . '_' . rand());
    }

    /**
     * Test SMTP connection
     */
    public function test_connection()
    {
        try {
            $this->mailer->smtpConnect();
            $this->mailer->smtpClose();

            return [
                'status' => 'success',
                'message' => 'SMTP connection successful'
            ];
        } catch (Exception $e) {
            return [
                'status' => 'failed',
                'message' => 'SMTP connection failed: ' . $e->getMessage()
            ];
        }
    }

    /**
     * Send test email
     */
    public function send_test_email($to_email, $to_name = '')
    {
        $test_data = [
            'to_email' => $to_email,
            'to_name' => $to_name,
            'subject' => 'Test Email from ' . $this->smtp_config['from_name'],
            'body' => $this->get_test_email_template(),
            'tracking_id' => 'test_' . time()
        ];

        return $this->send_single($test_data);
    }

    /**
     * Get test email template
     */
    private function get_test_email_template()
    {
        return '
        <html>
        <head>
            <style>
                body { font-family: Arial, sans-serif; margin: 0; padding: 20px; background-color: #f4f4f4; }
                .container { max-width: 600px; margin: 0 auto; background: white; padding: 20px; border-radius: 5px; }
                .header { background: #007cba; color: white; padding: 20px; text-align: center; margin: -20px -20px 20px -20px; }
                .footer { margin-top: 30px; padding-top: 20px; border-top: 1px solid #eee; font-size: 12px; color: #666; }
            </style>
        </head>
        <body>
            <div class="container">
                <div class="header">
                    <h1>IT - Email Marketing Test</h1>
                </div>
                <div class="content">
                    <p>Hello there!</p>
                    <p>This is a test email from Email Marketing System.</p>
                    <p>If you received this email, SMTP configuration is working correctly.</p>
                    <p><strong>Test Details:</strong></p>
                    <ul>
                        <li>Sent at: ' . date('Y-m-d H:i:s') . '</li>
                        <li>SMTP Host: ' . $this->smtp_config['smtp_host'] . '</li>
                        <li>SMTP Port: ' . $this->smtp_config['smtp_port'] . '</li>
                    </ul>
                    <p><a href="https://example.com" style="color: #007cba;">Test tracking link</a></p>
                    <p>Thankies,</p>
                    <p>IT</p>
                </div>
                <div class="footer">
                    <p>This is an automated test email from Email Marketing System by IT.</p>
                </div>
            </div>
        </body>
        </html>';
    }

    /**
     * Get current SMTP configuration (for debugging)
     */
    public function get_smtp_config()
    {
        // Hide sensitive data
        $safe_config = $this->smtp_config;
        $safe_config['smtp_password'] = !empty($safe_config['smtp_password']) ? '***hidden***' : '';

        return $safe_config;
    }

    /**
     * Update SMTP configuration
     */
    public function update_smtp_config($new_config)
    {
        $this->smtp_config = array_merge($this->smtp_config, $new_config);
        $this->init_phpmailer();
    }

    private function validate_email($email)
    {
        return filter_var($email, FILTER_VALIDATE_EMAIL) !== false;
    }
}