systemquery/src/lib/agent/Peer.mjs

"use strict";

import { EventEmitter, once } from 'events';
import Connection from '../transport/Connection.mjs';

class Peer extends EventEmitter {
	get address() { return this.connection.address; }
	get port() { return this.connection.port; }
	get remote_endpoint() {
		return { address: this.address, port: this.port };
	}
	
	constructor(server, connection) {
		super();
		
		this.id = null;
		
		/**
		 * The parent server this Peer is part of.
		 * @type {PeerServer}
		 */
		this.server = server;
		/**
		 * The underlying Connection.
		 * @type {Connection}
		 */
		this.connection = connection;
		
		/**
		 * A list of other peers known to this peer.
		 * May or may not actually be up to date.
		 * @type {{address:string,port:number}[]}
		 */
		this.known_peers = [];
	}
	
	///////////////////////////////////////////////////////////////////////////
	
	/**
	 * Accepts an existing connection as a new Peer.
	 * @param	{Connection}	connection	The Connection to accept.
	 * @return	{Promise<HelloMsg>}	A Promise that resolves once the initial handshake is complete.
	 */
	async __accept(connection) {
		this.connection = connection;
		const [ msg ] = await once(this.connection, "message-hello");
		this.__handle_hello(msg);
		
		this.emit("connect");
	}
	
	/**
	 * Initiates the handshake after opening a new connection.
	 * @return	{Promise<HelloMsg>}	A Promise that resolves after the initial peer handshake is complete.
	 */
	async __initiate() {
		await this.__send_hello();
		const [ msg ] = await once(this.connection, "message-hello");
		this.__handle_hello(msg);
		this.emit("connect");
	}
	
	__handle_hello(msg) {
		this.id = msg.id;
		this.known_peers = msg.peers;
	}
	
	async __send_hello() {
		await this.connection.send("hello", {
			id: this.server.our_id,
			peers: this.server.peers()
		});
	}
	
	///////////////////////////////////////////////////////////////////////////
	
	async destroy() {
		await this.connection.destroy();
		this.emit("destroy");
		this.removeAllListeners();
	}
}

Peer.Initiate = function(server, address, port) {
	const conn = await Connection.Create(server.secret_join, address, port);
	const peer = new Peer(server, conn);
	await peer.__initiate();
	return peer;
}

Peer.Accept = function(server, connection) {
	const peer = new Peer(server);
	await peer.__accept(connection);
	
	return peer;
}

export default Peer;