🏗️ Server plugin system

client.ts

import discord from 'eris'
import { Module, Server } from '../../server'

export interface DiscordEvents {
	clientConnected: []
}

interface DiscordModuleInjected {
	startClient: () => Promise<void>
}

export const DiscordModule = (
	token: string
): Module<DiscordModuleInjected, DiscordEvents> => (server, logger) => {
	const client = new discord.Client(token)

	client.on('ready', () => server.events.emit('clientConnected'))

	return Object.assign(server, {
		startClient: () => client.connect(),
	} as Server<DiscordModuleInjected, DiscordEvents>)
}

main.ts

import { handleError } from './error'
import { DiscordModule } from './modules/discord'
import { createServer } from './server'

async function main() {
	const server = createServer()
		.addModule(DiscordModule(''))
}

main().catch(handleError)

server.ts

import EventEmitter, { ValidEventTypes } from 'eventemitter3'
import { Logger } from 'tslog'
import { handleError } from '../error'

export type Module<
	M = {},
	E extends ValidEventTypes = {},
	IM = {},
	IE extends ValidEventTypes = DefaultServerEvents
> = (server: Server<IM, E & IE>, logger: Logger) => Server<M & IM, E & IE>

export interface DefaultServerEvents {
	error: [Error]
}

export type Server<ModuleInjected, Events extends ValidEventTypes> = {
	events: EventEmitter<Events>

	addModule: <
		M = {},
		E extends ValidEventTypes = {},
		IM = {},
		IE extends ValidEventTypes = DefaultServerEvents
	>(
		module: Module<M, E, IM, IE>
	) => Server<IM & M, E & IE>
} & ModuleInjected

export const createServer = () => {
	const logger = new Logger()
	const events = new EventEmitter<DefaultServerEvents>()

	const server: Server<{}, DefaultServerEvents> = {
		events,

		addModule: <
			M = {},
			E extends ValidEventTypes = {},
			IM = {},
			IE extends ValidEventTypes = DefaultServerEvents
		>(
			module: Module<M, E, IM, IE>
		) => {
			return module(
				(server as unknown) as Server<IM, E & IE>,
				logger.getChildLogger()
			)
		},
	}

	events.on('error', (error) => handleError(error))
	return server
}