Typesafe Pusher (validated with Zod)

TypesafePusher.ts

import PusherServer from 'pusher';
import { z, ZodSchema } from 'zod';
import PusherClient from 'pusher-js';

const client = new PusherClient('...', { cluster: '...' });
const server = new PusherServer({
    appId: '...',
    key: '...',
    secret: '...',
    cluster: '...',
});

type ObjKeyof<T> = T extends object ? keyof T : never;

type TypesafePusherSchema = Record<string, Record<string, ZodSchema>>;

interface TypesafePusherOptions<TSchema extends TypesafePusherSchema> {
    schema: TSchema;
}

export class TypesafePusher<TSchema extends TypesafePusherSchema> {
    constructor(private options: TypesafePusherOptions<TSchema>) {}

    server = (pusher: PusherServer) => ({
        trigger: <
            TChannel extends ObjKeyof<TSchema>,
            TEvent extends ObjKeyof<TSchema[TChannel]>,
        >(
            channel: TChannel,
            event: TEvent,
            data: z.infer<TSchema[TChannel][TEvent]>,
        ) => {
            pusher.trigger(
                channel,
                event,
                this.options.schema[channel]![event]!.parse(data),
            );
        },
    });

    client = (pusher: PusherClient) => ({
        subscribe: <TChannel extends ObjKeyof<TSchema>>(
            channelName: TChannel,
        ) => {
            const pusherChannel = pusher.subscribe(channelName);
            return {
                bind: <TEvent extends ObjKeyof<TSchema[TChannel]>>(
                    eventName: TEvent,
                    callback: (
                        data: z.infer<TSchema[TChannel][TEvent]>,
                    ) => void,
                ) => {
                    pusherChannel.bind(eventName, (data: any) =>
                        callback(
                            this.options.schema[channelName]![eventName]!.parse(
                                data,
                            ),
                        ),
                    );
                },
            };
        },
    });
}

const api = new TypesafePusher({
    schema: {
        myChannel: {
            myEvent: z.object({ id: z.string() }),
            myOtherEvent: z.object({ id: z.number() }),
        },
    },
});

api.server(server).trigger('myChannel', 'myEvent', { id: '2' });
api.client(client)
    .subscribe('myChannel')
    .bind('myEvent', data => console.log(data.id));