<?php
class Config {
    private static $instance = null;
    private $config = [];
    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    private function __construct() {
        $configPath = __DIR__ . '/../config/config.php';
        if (file_exists($configPath)) {
            $this->config = include $configPath;
        } else {
            $this->config = [
                'smtp' => ['port' => 25, 'host' => '0.0.0.0', 'max_connections' => 100],
                'pop3' => ['port' => 110, 'host' => '0.0.0.0', 'max_connections' => 100],
                'server' => ['domain' => 'test.com', 'admin_password' => 'admin123', 'max_email_size' => 10485760],
                'log' => ['path' => '../logs/', 'level' => 'info', 'max_file_size' => 10485760],
                'mailbox' => ['max_size' => 104857600]
            ];
        }
    }
    public function get($key, $default = null) {
        $keys = explode('.', $key);
        $value = $this->config;
        foreach ($keys as $k) {
            if (isset($value[$k])) {
                $value = $value[$k];
            } else {
                return $default;
            }
        }
        return $value;
    }
    public function set($key, $value) {
        $keys = explode('.', $key);
        $config = &$this->config;
        foreach ($keys as $i => $k) {
            if ($i === count($keys) - 1) {
                $config[$k] = $value;
            } else {
                if (!isset($config[$k]) || !is_array($config[$k])) {
                    $config[$k] = [];
                }
                $config = &$config[$k];
            }
        }
    }
    public function save() {
        $configPath = __DIR__ . '/../config/config.php';
        $content = "<?php\nreturn " . var_export($this->config, true) . ";\n";
        return file_put_contents($configPath, $content) !== false;
    }
    public function getAll() {
        return $this->config;
    }
}