<?php
/**
 * 配置管理类
 */
class Config {
    private static $instance = null;
    private $config = [];
    
    /**
     * 单例模式获取实例
     */
    public static function getInstance() {
        if (self::$instance === null) {
            self::$instance = new self();
        }
        return self::$instance;
    }
    
    /**
     * 构造函数，加载配置文件
     */
    private function __construct() {
        $configPath = __DIR__ . '/../config/config.php';
        if (file_exists($configPath)) {
            $this->config = include $configPath;
        } else {
            $this->config = $this->getDefaultConfig();
        }
    }
    
    /**
     * 获取默认配置
     */
    private function getDefaultConfig() {
        return [
            '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' => 10 * 1024 * 1024,
            ],
            'log' => [
                'path' => '../logs/',
                'level' => 'info',
                'max_file_size' => 10 * 1024 * 1024,
            ],
            'mailbox' => [
                'max_size' => 100 * 1024 * 1024,
            ],
        ];
    }
    
    /**
     * 获取配置值
     * @param string $key 配置键，支持点号分隔，如 'smtp.port'
     * @param mixed $default 默认值
     * @return mixed 配置值
     */
    public function get($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;
    }
    
    /**
     * 设置配置值
     * @param string $key 配置键
     * @param mixed $value 配置值
     */
    public function set($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];
            }
        }
    }
    
    /**
     * 保存配置到文件
     * @return bool 是否保存成功
     */
    public function save() {
        $configPath = __DIR__ . '/../config/config.php';
        $content = "<?php\n/**\n * 邮件服务器配置文件\n */\n\nreturn " . var_export($this->config, true) . ";\n";
        
        return file_put_contents($configPath, $content) !== false;
    }
    
    /**
     * 获取所有配置
     * @return array 所有配置
     */
    public function getAll() {
        return $this->config;
    }
}