<?php
// Minimal mail service for the workspace app (VM).
// Usage:
//   require_once __DIR__ . '/MailService.php';
//   // Generic:
//   MailService::sendMail($to, $subject, $htmlBody, $textBody = null, $opts = []);
//   // Contact form helper:
//   MailService::sendContactMessage($name, $email, $message, $to = null, $subject = 'New contact form');

class MailService
{
    // Universal mail sender (no attachments by design)
    public static function sendMail($to, string $subject, string $htmlBody, ?string $textBody = null, array $opts = [])
    {
        $cfg = self::loadConfig();
        $transport = strtolower((string)($cfg['transport'] ?? 'smtp'));

        if ($transport !== 'smtp') {
            return [
                'success' => false,
                'error' => 'MAIL_TRANSPORT must be set to smtp. Native mail() transport is disabled.',
            ];
        }

        if (!self::ensurePHPMailerLoaded()) {
            return [
                'success' => false,
                'error' => 'SMTP transport requires PHPMailer. Install it via Composer or make the system PHPMailer package available in include_path.',
            ];
        }

        return self::sendSmtpMail($cfg, $to, $subject, $htmlBody, $textBody, $opts);
    }

    private static function loadConfig(): array
    {
        $configPath = __DIR__ . '/config.php';
        if (!file_exists($configPath)) {
            throw new \RuntimeException('Mail config not found. Copy mail/config.sample.php to mail/config.php and fill in credentials.');
        }
        $cfg = require $configPath;
        if (!is_array($cfg)) {
            throw new \RuntimeException('Invalid mail config format: expected array');
        }
        return $cfg;
    }

    private static function ensurePHPMailerLoaded(): bool
    {
        if (class_exists('PHPMailer\PHPMailer\PHPMailer', false)) {
            return true;
        }

        $autoloadCandidates = [
            __DIR__ . '/../vendor/autoload.php',
            'libphp-phpmailer/autoload.php',
            'PHPMailer/PHPMailerAutoload.php',
        ];

        foreach ($autoloadCandidates as $candidate) {
            $resolved = self::resolveIncludePath($candidate);
            if ($resolved) {
                require_once $resolved;
                if (class_exists('PHPMailer\PHPMailer\PHPMailer', false)) {
                    return true;
                }
            }
        }

        $classFileSets = [
            [
                __DIR__ . '/phpmailer/src/Exception.php',
                __DIR__ . '/phpmailer/src/SMTP.php',
                __DIR__ . '/phpmailer/src/PHPMailer.php',
            ],
            [
                'libphp-phpmailer/src/Exception.php',
                'libphp-phpmailer/src/SMTP.php',
                'libphp-phpmailer/src/PHPMailer.php',
            ],
            [
                'PHPMailer/src/Exception.php',
                'PHPMailer/src/SMTP.php',
                'PHPMailer/src/PHPMailer.php',
            ],
            [
                'PHPMailer/Exception.php',
                'PHPMailer/SMTP.php',
                'PHPMailer/PHPMailer.php',
            ],
        ];

        foreach ($classFileSets as $files) {
            $resolvedFiles = [];
            foreach ($files as $file) {
                $resolved = self::resolveIncludePath($file);
                if (!$resolved) {
                    $resolvedFiles = [];
                    break;
                }
                $resolvedFiles[] = $resolved;
            }
            if (!$resolvedFiles) {
                continue;
            }
            foreach ($resolvedFiles as $resolvedFile) {
                require_once $resolvedFile;
            }
            if (class_exists('PHPMailer\PHPMailer\PHPMailer', false)) {
                return true;
            }
        }

        return class_exists('PHPMailer\PHPMailer\PHPMailer', false);
    }

    private static function resolveIncludePath(string $path): ?string
    {
        if (is_file($path)) {
            return $path;
        }

        $resolved = stream_resolve_include_path($path);
        if ($resolved && is_file($resolved)) {
            return $resolved;
        }

        return null;
    }

    private static function validateSmtpConfig(array $cfg): ?string
    {
        $required = [
            'smtp_host' => 'SMTP_HOST',
            'smtp_port' => 'SMTP_PORT',
            'smtp_user' => 'SMTP_USER',
            'smtp_pass' => 'SMTP_PASS',
        ];

        foreach ($required as $key => $envName) {
            $value = $cfg[$key] ?? null;
            if ($value === null || $value === '') {
                return sprintf('Missing SMTP configuration: %s', $envName);
            }
        }

        return null;
    }

    private static function buildRecipientList($to): array
    {
        if ($to) {
            if (is_string($to)) {
                return array_map('trim', explode(',', $to));
            }
            if (is_array($to)) {
                return $to;
            }
        }

        $defaultTo = getenv('MAIL_TO');
        if (!empty($defaultTo)) {
            return array_map('trim', explode(',', $defaultTo));
        }

        return [];
    }

    private static function sendSmtpMail(array $cfg, $to, string $subject, string $htmlBody, ?string $textBody, array $opts): array
    {
        $configError = self::validateSmtpConfig($cfg);
        if ($configError !== null) {
            return [ 'success' => false, 'error' => $configError ];
        }

        $mail = new PHPMailer\PHPMailer\PHPMailer(true);

        try {
            $mail->CharSet = 'UTF-8';
            $mail->Encoding = PHPMailer\PHPMailer\PHPMailer::ENCODING_BASE64;
            $mail->isSMTP();
            $mail->Host       = $cfg['smtp_host'] ?? '';
            $mail->Port       = (int)($cfg['smtp_port'] ?? 587);
            $secure = strtolower((string)($cfg['smtp_secure'] ?? 'tls'));
            if ($secure === 'ssl') {
                $mail->SMTPSecure = PHPMailer\PHPMailer\PHPMailer::ENCRYPTION_SMTPS;
            } elseif ($secure === 'tls') {
                $mail->SMTPSecure = PHPMailer\PHPMailer\PHPMailer::ENCRYPTION_STARTTLS;
            } else {
                $mail->SMTPSecure = false;
            }
            $mail->SMTPAuth   = true;
            $mail->Username   = $cfg['smtp_user'] ?? '';
            $mail->Password   = $cfg['smtp_pass'] ?? '';

            $fromEmail = $opts['from_email'] ?? ($cfg['from_email'] ?? 'no-reply@localhost');
            $fromName  = $opts['from_name']  ?? ($cfg['from_name']  ?? 'App');
            $mail->setFrom($fromEmail, $fromName);

            if (!empty($opts['reply_to']) && filter_var($opts['reply_to'], FILTER_VALIDATE_EMAIL)) {
                $mail->addReplyTo($opts['reply_to']);
            } elseif (!empty($cfg['reply_to']) && filter_var($cfg['reply_to'], FILTER_VALIDATE_EMAIL)) {
                $mail->addReplyTo($cfg['reply_to']);
            }

            $toList = self::buildRecipientList($to);
            $added = 0;
            foreach ($toList as $addr) {
                if (filter_var($addr, FILTER_VALIDATE_EMAIL)) {
                    $mail->addAddress($addr);
                    $added++;
                }
            }
            if ($added === 0) {
                return [ 'success' => false, 'error' => 'No recipients defined (set MAIL_TO or pass $to)' ];
            }

            foreach ((array)($opts['cc'] ?? []) as $cc) {
                if (filter_var($cc, FILTER_VALIDATE_EMAIL)) {
                    $mail->addCC($cc);
                }
            }
            foreach ((array)($opts['bcc'] ?? []) as $bcc) {
                if (filter_var($bcc, FILTER_VALIDATE_EMAIL)) {
                    $mail->addBCC($bcc);
                }
            }

            if (!empty($cfg['dkim_domain']) && !empty($cfg['dkim_selector']) && !empty($cfg['dkim_private_key_path'])) {
                $mail->DKIM_domain = $cfg['dkim_domain'];
                $mail->DKIM_selector = $cfg['dkim_selector'];
                $mail->DKIM_private = $cfg['dkim_private_key_path'];
            }

            $mail->isHTML(true);
            $mail->Subject = $subject;
            $mail->Body    = $htmlBody;
            $mail->AltBody = $textBody ?? trim(strip_tags($htmlBody));

            return [ 'success' => $mail->send() ];
        } catch (\Throwable $e) {
            return [ 'success' => false, 'error' => 'PHPMailer error: ' . $e->getMessage() ];
        }
    }

    private static function sendNativeMail(array $cfg, $to, string $subject, string $htmlBody, ?string $textBody, array $opts): array
    {
        $toList = self::buildRecipientList($to);
        $validTo = [];
        foreach ($toList as $addr) {
            if (filter_var($addr, FILTER_VALIDATE_EMAIL)) {
                $validTo[] = $addr;
            }
        }
        if (empty($validTo)) {
            return [ 'success' => false, 'error' => 'No recipients defined (set MAIL_TO or pass $to)' ];
        }

        $fromEmail = $opts['from_email'] ?? ($cfg['from_email'] ?? 'no-reply@localhost');
        $fromName  = $opts['from_name']  ?? ($cfg['from_name']  ?? 'App');
        $replyTo   = $opts['reply_to'] ?? ($cfg['reply_to'] ?? null);
        $textBody  = $textBody ?? trim(strip_tags($htmlBody));

        $boundary = 'flmail_' . md5((string)microtime(true) . $subject);
        $encodedSubject = '=?UTF-8?B?' . base64_encode($subject) . '?=';
        $safeFromName = mb_encode_mimeheader($fromName, 'UTF-8');

        $headers = [
            'MIME-Version: 1.0',
            'From: ' . $safeFromName . ' <' . $fromEmail . '>',
            'Content-Type: multipart/alternative; boundary="' . $boundary . '"',
        ];

        if ($replyTo && filter_var($replyTo, FILTER_VALIDATE_EMAIL)) {
            $headers[] = 'Reply-To: ' . $replyTo;
        }

        $ccList = [];
        foreach ((array)($opts['cc'] ?? []) as $cc) {
            if (filter_var($cc, FILTER_VALIDATE_EMAIL)) {
                $ccList[] = $cc;
            }
        }
        if ($ccList) {
            $headers[] = 'Cc: ' . implode(', ', $ccList);
        }

        $bccList = [];
        foreach ((array)($opts['bcc'] ?? []) as $bcc) {
            if (filter_var($bcc, FILTER_VALIDATE_EMAIL)) {
                $bccList[] = $bcc;
            }
        }
        if ($bccList) {
            $headers[] = 'Bcc: ' . implode(', ', $bccList);
        }

        $message = "--{$boundary}
"
            . "Content-Type: text/plain; charset=UTF-8
"
            . "Content-Transfer-Encoding: 8bit

"
            . $textBody . "

"
            . "--{$boundary}
"
            . "Content-Type: text/html; charset=UTF-8
"
            . "Content-Transfer-Encoding: 8bit

"
            . $htmlBody . "

"
            . "--{$boundary}--
";

        $ok = @mail(implode(', ', $validTo), $encodedSubject, $message, implode("
", $headers));
        if (!$ok) {
            return [ 'success' => false, 'error' => 'Native mail() failed' ];
        }

        return [ 'success' => true ];
    }

    // Send a contact message
    // $to can be: a single email string, a comma-separated list, an array of emails, or null (fallback to MAIL_TO/MAIL_FROM)
    public static function sendContactMessage(string $name, string $email, string $message, $to = null, string $subject = 'New contact form')
    {
        $safeName  = htmlspecialchars($name, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
        $safeEmail = htmlspecialchars($email, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
        $safeBody  = nl2br(htmlspecialchars($message, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8'));

        $html = "<p><strong>Name:</strong> {$safeName}</p><p><strong>Email:</strong> {$safeEmail}</p><hr>{$safeBody}";
        $text = "Name: {$name}
Email: {$email}

{$message}";
        $opts = [];
        if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
            $opts['reply_to'] = $email;
        }

        return self::sendMail($to, $subject, $html, $text, $opts);
    }
}