<?php

use PhpParser\Error;
use PhpParser\Node;
use PhpParser\NodeDumper;
use PhpParser\NodeFactory;
use PhpParser\NodeTraverser;
use PhpParser\NodeVisitorAbstract;
use PhpParser\ParserFactory;
use PhpParser\PrettyPrinter\Standard;
use Psr\Http\Message\ResponseInterface;

class MiddlewareProxyGenerator {
    private static string $cacheFile = __DIR__ . '/middleware_proxy.php';
    private static NodeFactory $factory;

    public static function generateProxy(array $middlewares): string {
        self::$factory = new NodeFactory();

        // 创建类结构（v5.5.0兼容写法）
        $class = new Node\Stmt\Class_(
            'MiddlewareProxy',
            [
                'implements' => [new Node\Name\FullyQualified(\Psr\Http\Server\MiddlewareInterface::class)],
                'stmts' => []
            ]
        );

        // 生成中间件调用链
        $method = self::createMethodNode($middlewares);
        $class->stmts[] = $method;

        // 生成代码
        $printer = new Standard();
        return $printer->prettyPrintFile([$class]);
    }

    private static function createMethodNode(array $middlewares): Node\Stmt\Function_ {
        $method = new Node\Stmt\Function_(
            'process',
            [
                'params' => [
                    new Node\Param(
                        new Node\Expr\Variable('request'),
                        null,
                        new Node\UnionType([new Node\Expr\Variable(\Psr\Http\Message\ServerRequestInterface::class)])
                    ),
                    new Node\Param(
                        new Node\Expr\Variable('handler'),
                        null,
                        new Node\UnionType([new Node\Expr\Variable(\Psr\Http\Server\RequestHandlerInterface::class)])
                    )
                ],
                'returnType' => new Node\Name(ResponseInterface::class),
                'stmts' => []
            ]
        );

        // 生成中间件调用链（v5.5.0闭包写法）
        $chain = [];
        $count = count($middlewares);
        for ($i = 0; $i < $count; $i++) {
            $className = $middlewares[$i]::class;
            $chain[] = self::createMiddlewareCall($i, $className, $count);
        }

        $method->stmts = array_reverse($chain);
        return $method;
    }

    private static function createMiddlewareCall(int $index, string $className, int $count): Node {
        $mwVar = new Node\Expr\Variable("mw{$index}");
        $nextHandler = new Node\Expr\Variable("next");

        // 创建中间件实例（v5.5.0兼容）
        $instanciate = new Node\Expr\New_($className);

        // 创建闭包表达式（v5.5.0语法）
        $closure = new Node\Expr\Closure([
            'static' => true,
            'params' => [new Node\Param($nextHandler)],
            'stmts' => [
                new Node\Stmt\Expression(
                    new Node\Expr\MethodCall(
                        $instanciate,
                        'process',
                        [new Node\Arg($nextHandler), new Node\Arg($mwVar)]
                    )
                )
            ]
        ]);

        return new Node\Stmt\Expression($closure);
    }
}

// 生成代理类代码
$middlewares = [AuthMiddleware::class, LogMiddleware::class];
$proxyCode = MiddlewareProxyGenerator::generateProxy($middlewares);

// 写入代理类文件
file_put_contents(MiddlewareProxyGenerator::$cacheFile, $proxyCode);