import { Callbag } from "callbag";

import { ClientMessage, MessageTypes, ServerMessage } from "./LockstepClient";

type Client<LocalInput, State> = Callbag<ServerMessage<LocalInput[], State>, ClientMessage<LocalInput, State>>;

/** Stub loopback server that handles a single client, for schemes where GlobalInput = LocalInput[] */
export function Loopback<LocalInput, State>(start: number, data?: Client<LocalInput, State> | ClientMessage<LocalInput, State>) {
    if(start != 0) return;

    const sink = data as Client<LocalInput, State>;

    sink(0, (type: number, data?: Client<LocalInput, State> | ClientMessage<LocalInput, State>) => {
        if(type == 1) {
            // message from client; just reflect for now
            const message = data as ClientMessage<LocalInput, State>;
            switch(message.t) {
                case MessageTypes.INPUT:
                    sink(1, {
                        t: MessageTypes.INPUT,
                        i: [message.i],
                    });
                    break;
            }
        }
    });
    sink(1, {t: MessageTypes.SET_STATE, u: 0, s: {}});
};