class VarDumper

class VarDumper {
    
    /**
     * @var callable|null
     */
    private static $handler;
    public static function dump(mixed $var, ?string $label = null) : mixed {
        if (null === self::$handler) {
            self::register();
        }
        return (self::$handler)($var, $label);
    }
    public static function setHandler(?callable $callable) : ?callable {
        $prevHandler = self::$handler;
        // Prevent replacing the handler with expected format as soon as the env var was set:
        if (isset($_SERVER['VAR_DUMPER_FORMAT'])) {
            return $prevHandler;
        }
        self::$handler = $callable;
        return $prevHandler;
    }
    private static function register() : void {
        $cloner = new VarCloner();
        $cloner->addCasters(ReflectionCaster::UNSET_CLOSURE_FILE_INFO);
        $format = $_SERVER['VAR_DUMPER_FORMAT'] ?? null;
        switch (true) {
            case 'html' === $format:
                $dumper = new HtmlDumper();
                break;
            case 'cli' === $format:
                $dumper = new CliDumper();
                break;
            case 'server' === $format:
            case $format && 'tcp' === parse_url($format, \PHP_URL_SCHEME):
                $host = 'server' === $format ? $_SERVER['VAR_DUMPER_SERVER'] ?? '127.0.0.1:9912' : $format;
                $dumper = \in_array(\PHP_SAPI, [
                    'cli',
                    'phpdbg',
                    'embed',
                ], true) ? new CliDumper() : new HtmlDumper();
                $dumper = new ServerDumper($host, $dumper, self::getDefaultContextProviders());
                break;
            default:
                $dumper = \in_array(\PHP_SAPI, [
                    'cli',
                    'phpdbg',
                    'embed',
                ], true) ? new CliDumper() : new HtmlDumper();
        }
        if (!$dumper instanceof ServerDumper) {
            $dumper = new ContextualizedDumper($dumper, [
                new SourceContextProvider(),
            ]);
        }
        self::$handler = function ($var, ?string $label = null) use ($cloner, $dumper) {
            $var = $cloner->cloneVar($var);
            if (null !== $label) {
                $var = $var->withContext([
                    'label' => $label,
                ]);
            }
            $dumper->dump($var);
        };
    }
    private static function getDefaultContextProviders() : array {
        $contextProviders = [];
        if (!\in_array(\PHP_SAPI, [
            'cli',
            'phpdbg',
            'embed',
        ], true) && class_exists(Request::class)) {
            $requestStack = new RequestStack();
            $requestStack->push(Request::createFromGlobals());
            $contextProviders['request'] = new RequestContextProvider($requestStack);
        }
        $fileLinkFormatter = class_exists(FileLinkFormatter::class) ? new FileLinkFormatter(null, $requestStack ?? null) : null;
        return $contextProviders + [
            'cli' => new CliContextProvider(),
            'source' => new SourceContextProvider(null, null, $fileLinkFormatter),
        ];
    }

}