<?php

namespace Coroutine\Server;

use Kiri\Di\Context;
use Kiri\Di\Inject\Container;
use Kiri\Router\Constrict\ConstrictRequest;
use Psr\Http\Message\RequestInterface;
use Swoole\Coroutine;
use Swoole\Coroutine\Http\Server;
use Swoole\Http\Request;
use Swoole\Http\Response;
use Swoole\WebSocket\CloseFrame;
use Throwable;

abstract class Websocket
{
	#[Container(Transport::class)]
	public Transport $transport;


	/**
	 * @var Config
	 */
	public Config $config;


	/**
	 * @param Config $config
	 * @return void
	 */
	public function start(Config $config): void
	{
		$this->config = $config;
		$this->configureRuntime();
		$this->onStart();

		$server = new Server($config->host, $config->port, false);
		$this->configureServer($server);

		$server->handle($config->normalizePath($config->websocketPath), fn(Request $request, Response $ws) => $this->handler($request, $ws));
		if ($config->exposeOnlineLists) {
			$server->handle($config->normalizePath($config->onlineListPath), fn(Request $request, Response $ws) => $this->getLists($request, $ws));
		}

		echo 'websocket server start at ' . $config->host . ':' . $config->port . PHP_EOL;
		$server->start();
	}


	/**
	 * @param Request  $request
	 * @param Response $ws
	 * @return void
	 */
	public function getLists(Request $request, Response $ws): void
	{
		try {
			if (!$this->config->exposeOnlineLists) {
				throw new \RuntimeException('Not found.', 404);
			}

			$psr7Request = ConstrictRequest::builder($request);
			if (!$this->authorizeOnlineListRequest($psr7Request)) {
				throw new \RuntimeException('Unauthorized.', 401);
			}

			$payload = json_encode($this->transport->getLists(), JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
			if ($payload === false) {
				$payload = '[]';
			}

			@$ws->header('Content-Type', 'application/json; charset=utf-8');
			$ws->end($payload);
		} catch (Throwable $throwable) {
			$this->throwable($ws, $throwable, false);
		}
	}


	/**
	 * @param Request  $request
	 * @param Response $ws
	 * @return void
	 */
	public function handler(Request $request, Response $ws): void
	{
		$upgraded = false;
		$userId = null;
		$fd = null;

		try {
			$psr7Request = $this->authorizeConnection($request);

			if (!$ws->upgrade()) {
				throw new \RuntimeException('Connection upgrade to websocket failed.', 500);
			}

			$upgraded = true;
			$userId = $psr7Request->getAuthority()->getUniqueId();

			$connection = new Struct($psr7Request->getAuthority(), $request, $ws);
			$fd = $connection->fd;

			$this->transport->add($userId, $connection);
			defer(function () use ($userId, $fd) {
				$this->transport->remove($userId, $fd);
			});

			@$ws->push((string)$userId);

			$this->onBeforeMessageLoop();

			while (true) {
				$frame = $ws->recv();
				if ($frame === '' || $frame === false || $frame === null) {
					break;
				}

				if ($frame instanceof CloseFrame) {
					break;
				}

				$payload = (string)($frame->data ?? '');
				if ($payload === 'close') {
					break;
				}

				$this->assertPayloadSize($payload);
				$this->transport->touch($userId, $fd);
				$this->onMessage($psr7Request, $payload);
			}
		} catch (Throwable $throwable) {
			$this->throwable($ws, $throwable, $upgraded);
		} finally {
			if ($userId !== null) {
				$this->onDisconnect($userId);
			}
		}
	}


	/**
	 * @return void
	 */
	abstract public function onBeforeMessageLoop(): void;


	/**
	 * @param Request $request
	 * @return ConstrictRequest
	 */
	protected function authorizeConnection(Request $request): RequestInterface
	{
		/** @var RequestInterface $psr7Request */
		$psr7Request = Context::set(RequestInterface::class, ConstrictRequest::builder($request));
		if (!$psr7Request->hasQuery($this->config->authKey)) {
			throw new \RuntimeException('Missing auth parameter.', 400);
		}

		if (!$this->onConnected($psr7Request) || $psr7Request->getAuthority() === null) {
			throw new \RuntimeException('Unauthorized.', 401);
		}

		return $psr7Request;
	}


	/**
	 * @param ConstrictRequest $request
	 * @return bool
	 */
	protected function authorizeOnlineListRequest(RequestInterface $request): bool
	{
		if (!$request->hasQuery($this->config->authKey)) {
			return false;
		}

		return $this->canViewOnlineLists($request) && $request->getAuthority() !== null;
	}


	/**
	 * @param ConstrictRequest $request
	 * @return bool
	 */
	protected function canViewOnlineLists(ConstrictRequest $request): bool
	{
		return $this->onConnected($request);
	}


	/**
	 * @return void
	 */
	private function configureRuntime(): void
	{
		if ($this->config->maxCoroutine > 0 && class_exists(Coroutine::class)) {
			Coroutine::set([
				'max_coroutine' => $this->config->maxCoroutine,
			]);
		}
	}


	/**
	 * @param Server $server
	 * @return void
	 */
	private function configureServer(Server $server): void
	{
		if (!method_exists($server, 'set')) {
			return;
		}

		$settings = [];
		if ($this->config->maxPackageSize > 0) {
			$settings['package_max_length'] = $this->config->maxPackageSize;
		}
		if ($this->config->maxFrameSize > 0) {
			$settings['websocket_max_frame_size'] = $this->config->maxFrameSize;
		}

		if ($settings !== []) {
			$server->set($settings);
		}
	}


	/**
	 * @param string $payload
	 * @return void
	 */
	private function assertPayloadSize(string $payload): void
	{
		$size = strlen($payload);

		if ($this->config->maxPackageSize > 0 && $size > $this->config->maxPackageSize) {
			throw new \RuntimeException('Payload too large.', 413);
		}

		if ($this->config->maxFrameSize > 0 && $size > $this->config->maxFrameSize) {
			throw new \RuntimeException('Frame too large.', 413);
		}
	}


	/**
	 * @param Response  $ws
	 * @param Throwable $throwable
	 * @param bool      $upgraded
	 * @return void
	 */
	private function throwable(Response $ws, Throwable $throwable, bool $upgraded): void
	{
		$status = $throwable->getCode();
		if (!in_array($status, [400, 401, 403, 404, 409, 413, 500], true)) {
			$status = 500;
		}

		$message = match ($status) {
			400 => 'Bad Request',
			401 => 'Unauthorized',
			403 => 'Forbidden',
			404 => 'Not Found',
			409 => 'Conflict',
			413 => 'Payload Too Large',
			default => 'Internal Server Error',
		};

		error_log(sprintf(
			'[%s] %s in %s:%d',
			static::class,
			$throwable->getMessage(),
			$throwable->getFile(),
			$throwable->getLine(),
		));

		if ($upgraded) {
			@$ws->close();
			return;
		}

		@$ws->setStatusCode($status);
		$ws->end($message);
	}


	/**
	 * @param RequestInterface $request
	 * @return bool
	 */
	abstract public function onConnected(RequestInterface $request): bool;


	/**
	 * @return void
	 */
	abstract public function onStart(): void;


	/**
	 * @param RequestInterface $psr7Request
	 * @param string           $frame
	 * @return void
	 */
	abstract public function onMessage(RequestInterface $psr7Request, string $frame): void;


	/**
	 * @param int $userId
	 * @return void
	 */
	abstract public function onDisconnect(int $userId): void;
}