feat: implement global autoresponder plugin

exec/lib/DirectAdminUser.php

@@ -0,0 +1,78 @@
+<?php
+declare(strict_types=1);
+
+final class DirectAdminUser
+{
+    private string $username;
+    private string $skin;
+    private string $language;
+    private string $configDir;
+
+    public function __construct(string $username, string $skin = 'enhanced', string $language = 'en', string $configDir = Settings::CONFIG_DIR)
+    {
+        if (!preg_match('/^[A-Za-z0-9._-]+$/', $username)) {
+            throw new InvalidArgumentException('Invalid username');
+        }
+        $this->username = $username;
+        $this->skin = $skin !== '' ? $skin : 'enhanced';
+        $this->language = $language !== '' ? strtolower($language) : 'en';
+        $this->configDir = $configDir;
+    }
+
+    public static function fromEnvironment(Settings $settings): self
+    {
+        $username = getenv('USERNAME') ?: getenv('USER') ?: getenv('DA_USER') ?: '';
+        if ($username === '' && isset($_SERVER['USERNAME'])) {
+            $username = (string)$_SERVER['USERNAME'];
+        }
+        if ($username === '') {
+            throw new RuntimeException('Cannot determine DirectAdmin user');
+        }
+        $skin = getenv('SKIN') ?: (string)($_SERVER['SKIN'] ?? 'enhanced');
+        $lang = self::readLanguage($username) ?: $settings->defaultLanguage();
+        return new self($username, $skin, $lang);
+    }
+
+    public function username(): string
+    {
+        return $this->username;
+    }
+
+    public function skin(): string
+    {
+        return $this->skin;
+    }
+
+    public function language(): string
+    {
+        return $this->language;
+    }
+
+    public function hasPluginAccess(Settings $settings): bool
+    {
+        $override = $this->configDir . '/users/' . $this->username . '.conf';
+        if (is_file($override)) {
+            $data = Settings::load($override);
+            return $data->getBool('enabled', $settings->defaultEnable());
+        }
+        return $settings->defaultEnable();
+    }
+
+    private static function readLanguage(string $username): string
+    {
+        $path = '/usr/local/directadmin/data/users/' . $username . '/user.conf';
+        if (!is_file($path)) {
+            return '';
+        }
+        $lines = file($path, FILE_IGNORE_NEW_LINES);
+        if ($lines === false) {
+            return '';
+        }
+        foreach ($lines as $line) {
+            if (str_starts_with($line, 'language=')) {
+                return strtolower(trim(substr($line, 9)));
+            }
+        }
+        return '';
+    }
+}