<?php

declare(strict_types=1);

namespace Blax\WebRtc\Tests;

use Blax\WebRtc\Signaling\RelaySignalingHandler;
use Blax\Ws\WebSocketServer;
use PHPUnit\Framework\TestCase;
use React\EventLoop\StreamSelectLoop;
use React\Socket\ConnectionInterface;
use React\Socket\Connector;

/**
 * End-to-end proof that the WebRTC relay composes with the laravel-ws
 * WebSocketServer: a browser (hand-rolled RFC6455 client) connecting to
 * `webrtc:serve` gets a `welcome` with its peer id over a real WebSocket.
 */
final class WebSocketRelayServerTest extends TestCase
{
    public function test_a_browser_receives_welcome_over_a_real_websocket(): void
    {
        $loop = new StreamSelectLoop;

        $server = new WebSocketServer('127.0.0.1', 0, new RelaySignalingHandler);
        $server->boot($loop);

        $address = $server->address();
        $this->assertNotNull($address);
        $port = (int) parse_url($address, PHP_URL_PORT);

        $handshakeOk = false;
        $welcome = null;

        (new Connector([], $loop))
            ->connect("127.0.0.1:{$port}")
            ->then(function (ConnectionInterface $conn) use (&$handshakeOk, &$welcome, $loop) {
                $buffer = '';
                $upgraded = false;

                $conn->on('data', function ($data) use (&$buffer, &$upgraded, &$handshakeOk, &$welcome, $conn, $loop) {
                    $buffer .= $data;

                    if (! $upgraded) {
                        $end = strpos($buffer, "\r\n\r\n");
                        if ($end === false) {
                            return;
                        }
                        $handshakeOk = str_contains(substr($buffer, 0, $end), ' 101 ');
                        $buffer = substr($buffer, $end + 4);
                        $upgraded = true;
                        if (! $handshakeOk) {
                            $loop->stop();

                            return;
                        }
                    }

                    // The server pushes a `welcome` frame on connect (no client frame needed).
                    $decoded = self::decodeServerTextFrame($buffer);
                    if ($decoded !== null) {
                        $welcome = json_decode($decoded, true);
                        $conn->close();
                        $loop->stop();
                    }
                });

                $key = base64_encode(random_bytes(16));
                $conn->write(
                    "GET / HTTP/1.1\r\n".
                    "Host: 127.0.0.1\r\n".
                    "Upgrade: websocket\r\n".
                    "Connection: Upgrade\r\n".
                    "Sec-WebSocket-Key: {$key}\r\n".
                    "Sec-WebSocket-Version: 13\r\n\r\n"
                );
            });

        $loop->addTimer(3.0, fn () => $loop->stop());
        $loop->run();
        $server->shutdown();

        $this->assertTrue($handshakeOk, 'server should return a 101 upgrade');
        $this->assertSame('welcome', $welcome['type'] ?? null);
        $this->assertArrayHasKey('peer', (array) $welcome);
    }

    /** Decode one unmasked server->client text frame (payload < 126 bytes), or null. */
    private static function decodeServerTextFrame(string $data): ?string
    {
        if (strlen($data) < 2) {
            return null;
        }
        $length = ord($data[1]) & 0x7F;
        if ($length >= 126 || strlen($data) < 2 + $length) {
            return null;
        }

        return substr($data, 2, $length);
    }
}