// 容器类 (简化版)
class Container {
    private $bindings = [];

    public function bind($abstract, $concrete) {
        $this->bindings[$abstract] = $concrete;
    }

    public function resolve($abstract) {
        if (isset($this->bindings[$abstract])) {
            $concrete = $this->bindings[$abstract];
            if (is_callable($concrete)) {
                return $concrete($this);
            }
            return $concrete;
        }

        return null; // 或者抛出异常
    }
}

// 示例：数据库连接类
class DatabaseConnection {
    public function __construct() {
        // 实际的数据库连接逻辑
        echo "Database connection established.
";
    }

    public function query($sql) {
        echo "Executing query: " . $sql . "
";
        return ['result' => 'some data']; // 模拟数据
    }
}

// 修改控制器，通过构造函数注入依赖
class UserController {
    private $db;

    public function __construct(DatabaseConnection $db) {
        $this->db = $db;
    }

    public function indexAction() {
        $data = $this->db->query("SELECT * FROM users");
        var_dump($data);
    }
}

// 使用容器
$container = new Container();
$container->bind(DatabaseConnection::class, function() {
    return new DatabaseConnection();
});

// 解析 UserController，自动注入 DatabaseConnection
$userController = new UserController($container->resolve(DatabaseConnection::class));
$userController->indexAction();

class Model {
    protected static $tableName; // 表名
    protected static $primaryKey = 'id'; // 主键

    private static $db; // 数据库连接

    public function __construct($data = []) {
        foreach ($data as $key => $value) {
            $this->$key = $value;
        }
    }

    // 初始化数据库连接 (单例模式)
    public static function setDb(PDO $db) {
        self::$db = $db;
    }

    public static function find($id) {
        $tableName = static::$tableName;
        $primaryKey = static::$primaryKey;

        $stmt = self::$db->prepare("SELECT * FROM {$tableName} WHERE {$primaryKey} = ?");
        $stmt->execute([$id]);
        $result = $stmt->fetch(PDO::FETCH_ASSOC);

        if ($result) {
            return new static($result);
        }

        return null;
    }

    public static function findAll() {
         $tableName = static::$tableName;
         $stmt = self::$db->prepare("SELECT * FROM {$tableName}");
         $stmt->execute();
         $results = $stmt->fetchAll(PDO::FETCH_ASSOC);

         $objects = [];
         foreach ($results as $result) {
             $objects[] = new static($result);
         }
         return $objects;
    }

    public function save() {
        $tableName = static::$tableName;
        $primaryKey = static::$primaryKey;

        $fields = get_object_vars($this);
        unset($fields[$primaryKey]); // 排除主键

        $columns = implode(',', array_keys($fields));
        $valuesPlaceholder = str_repeat('?,', count($fields) - 1) . '?'; // 构建 ? 占位符
        $values = array_values($fields);

        $sql = "INSERT INTO {$tableName} ({$columns}) VALUES ({$valuesPlaceholder})";

        $stmt = self::$db->prepare($sql);
        $stmt->execute($values);

        // 设置自增 ID (如果适用)
        $this->{$primaryKey} = self::$db->lastInsertId();

        return true;
    }
}

// 示例：User 模型
class User extends Model {
    protected static $tableName = 'users';
    protected static $primaryKey = 'id';
    public $id;
    public $username;
    public $email;
}

// 使用示例
try {
    $db = new PDO('mysql:host=localhost;dbname=test', 'user', 'password');
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    Model::setDb($db); // 设置数据库连接
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
    exit;
}

// 创建新用户
$newUser = new User(['username' => 'testuser', 'email' => 'test@example.com']);
$newUser->save();

// 查找用户
$user = User::find($newUser->id);
echo "User ID: " . $user->id . ", Username: " . $user->username . "
";

//查找所有用户
$users = User::findAll();
foreach($users as $u){
    echo "User ID: " . $u->id . ", Username: " . $u->username . "
";
}

class TemplateEngine {
    private $templateDir;
    private $data = [];

    public function __construct($templateDir) {
        $this->templateDir = $templateDir;
    }

    public function assign($key, $value) {
        $this->data[$key] = $value;
    }

    public function render($templateFile) {
        $templatePath = $this->templateDir . '/' . $templateFile;

        if (!file_exists($templatePath)) {
            throw new Exception("Template file not found: " . $templatePath);
        }

        // 将数据提取到局部作用域
        extract($this->data);

        // 开始输出缓冲
        ob_start();

        // 包含模板文件
        include $templatePath;

        // 获取缓冲内容并清理
        $content = ob_get_clean();

        return $content;
    }
}

// 示例：使用模板引擎

// 创建模板引擎实例
$templateEngine = new TemplateEngine(ROOT_PATH . '/app/views');

// 传递数据
$templateEngine->assign('name', 'John Doe');
$templateEngine->assign('age', 30);

// 渲染模板
$output = $templateEngine->render('user/profile.php');

// 输出结果
echo $output;

// 示例模板文件 (app/views/user/profile.php)
?>
<!DOCTYPE html>
<html>
<head>
    <title>User Profile</title>
</head>
<body>
    <h1>User Profile</h1>
    <p>Name: <?php echo $name; ?></p>
    <p>Age: <?php echo $age; ?></p>
</body>
</html>