<?php

namespace App\Net;

use Evenement\EventEmitter;
use PhpWasmNetwork\Connection;
use PhpWasmNetwork\Event;
use PhpWasmNetwork\Network;

/**
 * A Link over a WebSocket (wss://…, port 443: it passes every firewall and proxy), with php-wasm-network, JumPHP's
 * network library: the browser's WebSocket in the page, a non-blocking socket on a desktop. The chat server
 * (caramail-server, its WebSocket port) speaks the little of the relay protocol needed: the client joins the room
 * "CHAT", where the server is peer 0; each binary message carries the applet's TCP bytes unchanged.
 *
 * poll() each frame (the window does it).
 */
final class WsLink extends EventEmitter implements Link
{
    public const ROOM = 'CHAT';

    private ?Connection $net = null;
    private bool $open = false;
    private bool $closed = false;

    public function __construct(private readonly string $url)
    {
    }

    public static function isUrl(string $server): bool
    {
        return (bool)preg_match('#^wss?://#i', $server);
    }

    public function poll(): void
    {
        if ($this->closed) {
            return;
        }
        if ($this->net === null) {
            // opened at the first poll: the window is drawn before a desktop connection's TLS handshake
            $this->net = Network::connect($this->url, ['transport' => 'ws']);
        }
        foreach ($this->net->poll() as $event) {
            switch ($event->type) {
                case Event::OPEN:
                    $this->net->joinRoom(self::ROOM);
                    break;
                case Event::ROOM:
                    if (!$this->open) {
                        $this->open = true;
                        $this->emit('open');
                    }
                    break;
                case Event::MESSAGE:
                    $this->emit('data', [$event->data]);
                    break;
                case Event::ERROR:
                    $info = $event->info();
                    $this->emit('error', [(string)($info['message'] ?? $info['code'] ?? 'network error')]);
                    break;
                case Event::CLOSE:
                    $this->finish('closed');
                    return;
            }
        }
        if ($this->net->state() === Connection::CLOSED) {
            $this->finish('closed');
        }
    }

    public function write(string $bytes): void
    {
        if ($this->open && $this->net !== null) {
            $this->net->send($bytes, 0);
        }
    }

    public function close(): void
    {
        $this->net?->close();
        $this->finish('closed');
    }

    private function finish(string $why): void
    {
        if ($this->closed) {
            return;
        }
        $this->closed = true;
        $this->open = false;
        $this->emit('close', [$why]);
    }
}