<?php
/**
 * Email Service
 * Handles email notifications via Mailgun
 */

class EmailService {
    private $config;
    private $enabled;

    public function __construct() {
        $appConfig = require __DIR__ . '/config.php';
        $this->config = $appConfig['email'];
        $this->enabled = $this->config['enabled'] ?? false;
    }

    /**
     * Send email via Mailgun API or SMTP
     */
    public function send($to, $subject, $text) {
        if (!$this->enabled) {
            error_log('Email not sent (service disabled): ' . $subject);
            return ['success' => true, 'message' => 'Email disabled'];
        }

        $service = $this->config['service'] ?? 'mailgun';

        if ($service === 'smtp') {
            return $this->sendViaSMTP($to, $subject, $text);
        } else {
            return $this->sendViaMailgunAPI($to, $subject, $text);
        }
    }

    /**
     * Send email via Mailgun API
     */
    private function sendViaMailgunAPI($to, $subject, $text) {
        try {
            $url = 'https://api.mailgun.net/v3/' . $this->config['domain'] . '/messages';

            $postData = [
                'from' => $this->config['from'],
                'to' => $to,
                'subject' => $subject,
                'text' => $text
            ];

            $ch = curl_init($url);
            curl_setopt_array($ch, [
                CURLOPT_POST => true,
                CURLOPT_POSTFIELDS => $postData,
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_USERPWD => 'api:' . $this->config['mailgun_api_key'],
                CURLOPT_HTTPAUTH => CURLAUTH_BASIC,
                CURLOPT_TIMEOUT => 10
            ]);

            $response = curl_exec($ch);
            $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
            $curlError = curl_error($ch);
            curl_close($ch);

            if ($curlError) {
                error_log('Email send failed: ' . $curlError);
                return [
                    'success' => false,
                    'error' => 'Email delivery failed',
                    'details' => $curlError
                ];
            }

            if ($httpCode !== 200) {
                error_log('Email send failed (HTTP ' . $httpCode . '): ' . $response);
                return [
                    'success' => false,
                    'error' => 'Email service error',
                    'details' => 'HTTP ' . $httpCode,
                    'httpCode' => $httpCode
                ];
            }

            error_log('Email sent successfully to ' . $to);

            return [
                'success' => true,
                'httpCode' => $httpCode
            ];

        } catch (Exception $e) {
            error_log('Email exception: ' . $e->getMessage());

            return [
                'success' => false,
                'error' => 'Email exception',
                'details' => $e->getMessage()
            ];
        }
    }

    /**
     * Send email via SMTP
     */
    private function sendViaSMTP($to, $subject, $text) {
        try {
            $from = $this->config['from'];
            $host = $this->config['smtp_host'];
            $port = $this->config['smtp_port'];
            $username = $this->config['smtp_username'];
            $password = $this->config['smtp_password'];

            // Build email message
            $headers = "From: {$from}\r\n";
            $headers .= "Reply-To: {$from}\r\n";
            $headers .= "X-Mailer: PHP/" . phpversion() . "\r\n";
            $headers .= "MIME-Version: 1.0\r\n";
            $headers .= "Content-Type: text/plain; charset=UTF-8\r\n";

            // Create SMTP connection
            $socket = fsockopen($host, $port, $errno, $errstr, 10);

            if (!$socket) {
                error_log('SMTP connection failed: ' . $errstr);
                return [
                    'success' => false,
                    'error' => 'SMTP connection failed',
                    'details' => $errstr
                ];
            }

            // SMTP conversation
            $this->smtpCommand($socket, null, 220);  // Wait for greeting
            $this->smtpCommand($socket, "EHLO " . $host, 250);
            $this->smtpCommand($socket, "AUTH LOGIN", 334);
            $this->smtpCommand($socket, base64_encode($username), 334);
            $this->smtpCommand($socket, base64_encode($password), 235);
            $this->smtpCommand($socket, "MAIL FROM: <{$from}>", 250);
            $this->smtpCommand($socket, "RCPT TO: <{$to}>", 250);
            $this->smtpCommand($socket, "DATA", 354);

            // Send email data
            $message = "Subject: {$subject}\r\n";
            $message .= $headers;
            $message .= "\r\n";
            $message .= $text . "\r\n";
            $message .= ".\r\n";

            $this->smtpCommand($socket, $message, 250);
            $this->smtpCommand($socket, "QUIT", 221);

            fclose($socket);

            error_log('Email sent via SMTP to ' . $to);

            return [
                'success' => true,
                'method' => 'smtp'
            ];

        } catch (Exception $e) {
            error_log('SMTP exception: ' . $e->getMessage());

            return [
                'success' => false,
                'error' => 'SMTP exception',
                'details' => $e->getMessage()
            ];
        }
    }

    /**
     * Send SMTP command and check response
     */
    private function smtpCommand($socket, $command, $expectedCode) {
        if ($command !== null) {
            fwrite($socket, $command . "\r\n");
        }

        $response = '';
        while ($line = fgets($socket, 515)) {
            $response .= $line;
            if (substr($line, 3, 1) === ' ') {
                break;
            }
        }

        $code = intval(substr($response, 0, 3));

        if ($code !== $expectedCode) {
            throw new Exception("SMTP Error: Expected {$expectedCode}, got {$code}. Response: {$response}");
        }

        return $response;
    }

    /**
     * Send process started notification
     */
    public function notifyStarted($userEmail, $filename) {
        $subject = 'Regional Hotfolder - Started';
        $text = "Document: $filename has been picked up for processing.";

        return $this->send($userEmail, $subject, $text);
    }

    /**
     * Send process completed notification
     */
    public function notifyCompleted($userEmail, $filename, $outputCount) {
        $subject = 'Regional Hotfolder - Completed';
        $text = "Document: $filename has completed processing.\n\n";
        $text .= "Generated $outputCount regional CSV files.\n";
        $text .= "Files should appear in OMG within 5 minutes.";

        return $this->send($userEmail, $subject, $text);
    }

    /**
     * Send error notification
     */
    public function notifyError($userEmail, $filename, $errorMessage) {
        $subject = 'Error - Regional Hotfolder';
        $text = "An error occurred while processing: $filename\n\n";
        $text .= "Error: $errorMessage\n\n";
        $text .= "Please check the file and try again.";

        return $this->send($userEmail, $subject, $text);
    }
}