<?php
declare(strict_types=1);

namespace App;

final class Mailer
{
    private string $logFile;
    private bool $logCleared = false;

    public function __construct(private App $app)
    {
        $base = dirname(__DIR__, 2);
        $this->logFile = $base . '/debug/mailer_debug.log';
    }

    private function log(string $msg, array $ctx = []): void
    {
        if (!defined('APP_DEBUG') || APP_DEBUG !== true) {
            return;
        }
        $line = '[' . date('Y-m-d H:i:s') . '] ' . $msg;
        if ($ctx) {
            $line .= ' ' . json_encode($ctx, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
        }
        $line .= "\n";
        $dir = dirname($this->logFile);
        if (!is_dir($dir)) {
            @mkdir($dir, 0775, true);
        }
        // For clarity keep only the latest run in the log: truncate once per request
        if ($this->logCleared === false) {
            @file_put_contents($this->logFile, '');
            $this->logCleared = true;
        }
        @file_put_contents($this->logFile, $line, FILE_APPEND);
    }

    private function templates(): array
    {
        $env = $this->app->config()->env;
        $root = __DIR__ . '/../../config/emailtemplates.php';
        $envPath = __DIR__ . "/../../config/{$env}/emailtemplates.php";
        $file = is_file($root) ? $root : $envPath;
        $emailtemplates = [];
        if (is_file($file)) {
            /** @noinspection PhpIncludeInspection */
            include $file; // populates $emailtemplates variable from included file
        }
        return is_array($emailtemplates ?? null) ? $emailtemplates : [];
    }

    private function renderTemplate(string $key, array $vars): array
    {
        $templates = $this->templates();
        $id = $templates[$key] ?? $key;
        $this->log('template_resolved_id', ['key' => $key, 'id' => $id]);

        $apiBase  = getenv('EMAILTEMPLATE_API_BASE') ?: '';
        $apiToken = getenv('EMAILTEMPLATE_API_TOKEN') ?: '';

        if ($apiBase && $apiToken) {
        $payload = [
            'template' => $id,
            'placeholders' => $vars,
        ];
            $payload['token'] = $apiToken;

            $payloadForLog = $payload;
            $payloadForLog['token'] = '[hidden length ' . strlen((string)$apiToken) . ']';
            $this->log('template_api_request_payload', [
                'url' => $apiBase,
                'payload' => $payloadForLog,
            ]);

            $this->log('template_api_request', ['template' => $id, 'placeholders' => array_keys($vars)]);
            $ctx = stream_context_create([
                'http' => [
                    'method' => 'POST',
                    'header' => "Content-Type: application/json\r\n",
                    'timeout' => 15,
                    'content' => json_encode($payload, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
                ],
            ]);
            $resp = @file_get_contents($apiBase, false, $ctx);
            if ($resp !== false) {
                $status = null;
                if (isset($http_response_header) && is_array($http_response_header)) {
                    foreach ($http_response_header as $hdr) {
                        if (preg_match('~^HTTP/\\S+\\s+(\\d+)~i', $hdr, $m)) {
                            $status = (int)$m[1];
                            break;
                        }
                    }
                }
                $this->log('template_api_response_raw', [
                    'status' => $status,
                    'body'   => $resp,
                ]);
                $decoded = json_decode($resp, true);
                if (is_array($decoded) && !empty($decoded['ok']) && !empty($decoded['html'])) {
                    $this->log('template_api_success', ['template' => $id, 'subject' => $decoded['subject'] ?? null, 'html_len' => strlen((string)$decoded['html'])]);
                    return [
                        'id' => $id,
                        'subject' => $decoded['subject'] ?? 'Papa-Kind-Treff',
                        'html' => $decoded['html'],
                    ];
                }
                $this->log('template_api_response_invalid', ['template' => $id, 'response' => $decoded]);
            } else {
                $this->log('template_api_unreachable', ['template' => $id]);
            }
        }

        // Fallback: einfacher Text
        $subject = 'Papa-Kind-Treff';
        $body = $id;
        foreach ($vars as $k => $v) {
            $body = str_replace(['{' . $k . '}', '{{' . $k . '}}'], (string)$v, $body);
        }
        $this->log('template_fallback_used', ['template' => $id]);
        return [
            'id' => $id,
            'subject' => $subject,
            'html' => nl2br(htmlspecialchars($body, ENT_QUOTES)),
        ];
    }

    public function sendTemplate(string $templateKey, string $to, array $vars = []): void
    {
        if (!filter_var($to, FILTER_VALIDATE_EMAIL)) {
            throw new \InvalidArgumentException('Invalid recipient email.');
        }

        $tpl = $this->renderTemplate($templateKey, $vars);
        $resolvedId = $tpl['id'] ?? $templateKey;
        $subject = $tpl['subject'] ?? 'Papa-Kind-Treff';
        $html = $tpl['html'] ?? '';

        $this->log('mail_rendered_template', [
            'template_key' => $templateKey,
            'template_id'  => $resolvedId,
            'subject'      => $subject,
            'html_len'     => strlen((string)$html),
            'html_preview' => substr((string)$html, 0, 200),
        ]);

        $transport = getenv('MAIL_TRANSPORT') ?: 'mail';
        $fromEmail = getenv('MAIL_FROM') ?: 'no-reply@' . $this->app->config()->primaryDomain;
        $fromName  = getenv('MAIL_FROM_NAME') ?: 'Papa-Kind-Treff';

        $this->log('mail_send_start', [
            'template_key' => $templateKey,
            'template_id'  => $resolvedId,
            'to' => $to,
            'transport' => $transport,
            'subject' => $subject
        ]);
        if ($transport === 'smtp') {
            $this->sendSmtp($to, $subject, $html, $fromEmail, $fromName);
        } else {
            $this->sendMailFn($to, $subject, $html, $fromEmail, $fromName);
        }
    }

    private function sendMailFn(string $to, string $subject, string $html, string $from, string $fromName): void
    {
        $headers = [];
        if ($from) {
            $headers[] = 'From: ' . sprintf('"%s" <%s>', addslashes($fromName), $from);
        }
        $headers[] = 'Content-Type: text/html; charset=utf-8';
        $ok = @mail($to, $subject, $html, implode("\r\n", $headers));
        $this->log('mail_mail_transport', ['to' => $to, 'ok' => $ok]);
        if (!$ok) {
            throw new \RuntimeException('mail() transport failed');
        }
    }

    private function sendSmtp(string $to, string $subject, string $html, string $from, string $fromName): void
    {
        $host = getenv('SMTP_HOST') ?: '';
        $port = (int)(getenv('SMTP_PORT') ?: 587);
        $user = getenv('SMTP_USER') ?: '';
        $pass = getenv('SMTP_PASS') ?: '';
        $secure = strtolower(getenv('SMTP_SECURE') ?: 'tls'); // tls|ssl|none

        if (!$host) {
            $this->log('mail_smtp_missing_host_fallback_mail', []);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }

        $proto = ($secure === 'ssl') ? 'ssl://' : '';
        $fp = @stream_socket_client($proto . $host . ':' . $port, $errno, $errstr, 15, STREAM_CLIENT_CONNECT);
        if (!$fp) {
            $this->log('mail_smtp_connect_failed', ['host' => $host, 'port' => $port, 'error' => $errstr]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }
        stream_set_timeout($fp, 15);

        $transcript = [];
        $readResponse = function (array $expectCodes = [], string $label = 'read') use ($fp, &$transcript): array {
            $lines = [];
            while (($line = fgets($fp, 515)) !== false) {
                $line = rtrim($line, "\r\n");
                $lines[] = $line;
                $transcript[] = $label . ': ' . $line;
                // SMTP multiline: code + '-' means more lines, code + ' ' means end
                if (strlen($line) >= 4 && $line[3] === ' ') {
                    break;
                }
            }
            $code = 0;
            if ($lines) {
                $code = (int)substr($lines[0], 0, 3);
            }
            return [
                'ok'    => !$expectCodes || in_array($code, $expectCodes, true),
                'code'  => $code,
                'lines' => $lines,
            ];
        };
        $write = function (string $cmd, string $label = 'write', bool $mask = false) use ($fp, &$transcript): void {
            $transcript[] = $label . ': ' . ($mask ? '[omitted]' : $cmd);
            fwrite($fp, $cmd . "\r\n");
        };

        $resp = $readResponse([220], 'greeting');
        if (!$resp['ok']) {
            fclose($fp);
            $this->log('mail_smtp_greeting_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
            $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }

        $write('EHLO ' . $this->app->config()->primaryDomain);
        $resp = $readResponse([250], 'ehlo');
        if (!$resp['ok']) {
            fclose($fp);
            $this->log('mail_smtp_ehlo_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
            $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }

        if ($secure === 'tls') {
            $write('STARTTLS');
            $resp = $readResponse([220], 'starttls');
            if (!$resp['ok'] || !stream_socket_enable_crypto($fp, true, STREAM_CRYPTO_METHOD_TLS_CLIENT)) {
                fclose($fp);
                $this->log('mail_smtp_starttls_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
                $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
                $this->sendMailFn($to, $subject, $html, $from, $fromName);
                return;
            }
            $write('EHLO ' . $this->app->config()->primaryDomain);
            $resp = $readResponse([250], 'ehlo-tls');
            if (!$resp['ok']) {
                fclose($fp);
                $this->log('mail_smtp_ehlo_tls_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
                $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
                $this->sendMailFn($to, $subject, $html, $from, $fromName);
                return;
            }
        }

        if ($user !== '') {
            $write('AUTH LOGIN');
            $resp = $readResponse([334], 'auth-login');
            if (!$resp['ok']) {
                fclose($fp);
                $this->log('mail_smtp_auth_login_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
                $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
                $this->sendMailFn($to, $subject, $html, $from, $fromName);
                return;
            }
            $write(base64_encode($user), 'auth-user', true);
            $resp = $readResponse([334], 'auth-user');
            if (!$resp['ok']) {
                fclose($fp);
                $this->log('mail_smtp_auth_user_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
                $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
                $this->sendMailFn($to, $subject, $html, $from, $fromName);
                return;
            }
            $write(base64_encode($pass), 'auth-pass', true);
            $resp = $readResponse([235], 'auth-pass');
            if (!$resp['ok']) {
                fclose($fp);
                $this->log('mail_smtp_auth_pass_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
                $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
                $this->sendMailFn($to, $subject, $html, $from, $fromName);
                return;
            }
        }

        $write('MAIL FROM: <' . $from . '>');
        $resp = $readResponse([250], 'mail-from');
        if (!$resp['ok']) {
            fclose($fp);
            $this->log('mail_smtp_mailfrom_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
            $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }

        $write('RCPT TO: <' . $to . '>');
        $resp = $readResponse([250, 251], 'rcpt-to');
        if (!$resp['ok']) {
            fclose($fp);
            $this->log('mail_smtp_rcpt_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
            $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }

        $write('DATA');
        $resp = $readResponse([354], 'data-start');
        if (!$resp['ok']) {
            fclose($fp);
            $this->log('mail_smtp_data_start_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
            $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }

        $msg = "From: {$fromName} <{$from}>\r\n";
        $msg .= "To: <{$to}>\r\n";
        $msg .= "Subject: {$subject}\r\n";
        $msg .= "MIME-Version: 1.0\r\n";
        $msg .= "Content-Type: text/html; charset=utf-8\r\n\r\n";
        $msg .= $html . "\r\n.\r\n";
        $write($msg, 'data', false);
        $resp = $readResponse([250], 'data-end');

        $write('QUIT');
        $readResponse([221], 'quit');
        fclose($fp);

        $this->log('mail_smtp_transcript', ['host' => $host, 'port' => $port, 'secure' => $secure, 'steps' => $transcript]);

        if (!$resp['ok']) {
            $this->log('mail_smtp_send_failed', ['host' => $host, 'port' => $port, 'resp' => $resp]);
            $this->sendMailFn($to, $subject, $html, $from, $fromName);
            return;
        }
        $this->log('mail_smtp_sent', ['to' => $to, 'host' => $host, 'port' => $port, 'secure' => $secure]);
    }
}