@woosh/meep-engine/src/engine/network/RemoteController.js

Pure JavaScript game engine. Fully featured and production ready.

import { BinaryBuffer } from "../../core/binary/BinaryBuffer.js";
import { assert } from "../../core/assert.js";

/*
 packet header structure
    - TAG       : 1 x utf8 string
    - ID        : 1 x uint32
    - PAYLOAD   : N x bytes
 */

export class RemoteController {
    /**
     *
     * @type {WebSocket|null}
     */
    #socket = null;

    #handlers = {};

    #bound_event_handler = this.#handle_message_event.bind(this)

    /**
     *
     * @param {string} tag
     * @param {function(BinaryBuffer):Promise} handler
     * @param {*} thisArg
     */
    addHandler(tag, handler, thisArg) {
        const existing = this.#handlers[tag];

        if (existing !== undefined) {
            throw new Error(`Handler for tag '${tag}' already exists`);
        }

        this.#handlers[tag] = {
            method: handler,
            scope: thisArg
        };
    }

    /**
     * NOTE: entire buffer contents will be sent up to current position
     * @param {string} tag
     * @param {BinaryBuffer} data
     */
    send(tag, data) {
        assert.isString(tag, 'tag');

        const buffer = new BinaryBuffer();

        buffer.writeUTF8String(tag);

        buffer.writeBytes(data.raw_bytes, 0, data.position);

        buffer.trim();

        this.#socket.send(buffer.data);
    }

    /**
     *
     * @param {MessageEvent} event
     * @private
     */
    async #handle_message_event(event) {

        /**
         * @type {ArrayBuffer}
         */
        const data = event.data;

        // console.log(`received message `, data);

        const buffer = BinaryBuffer.fromArrayBuffer(data);

        // read packet ID
        const packet_id = buffer.readUTF8String();

        const handler = this.#handlers[packet_id];

        if (handler === undefined) {
            console.error(`No handler for packet '${packet_id}'`);
            return;
        }

        try {
            await handler.method.call(handler.scope, buffer);
        } catch (e) {
            //
            console.error(`Failed to process remote call to '${packet_id}':`, e);
        }
    }

    /**
     *
     * @param {WebSocket} v
     */
    set socket(v) {
        if (this.#socket !== null) {
            // TODO unbind socket
        }

        this.#socket = v;

        this.#socket.binaryType = "arraybuffer";

        this.#socket.addEventListener('open', () => {
            console.log('socket connection open');
        });

        this.#socket.addEventListener('message', this.#bound_event_handler);
    }

}