novy-syndicate/src/secure-chat-moderator.ts

import { $claimNick, $joinedUser, asNickClaim, fromJoin, fromNickConflict, fromUserInfo, Join, NickConflict, UserId, UserInfo } from "./gen/secure-chat-protocol.js";
import { Assertion, Handle, Ref, Turn } from "./actor.js";
import { observe, during, $Observe, asObserve } from "./dataspace.js";

export default function (t: Turn, ds: Ref) {
    let nextUserId: UserId = 0;

    const nicks = new Map<string, UserId>();

    observe(t, ds, $Observe, during((t, o0) => {
        const o = asObserve(o0);
        if (o.label !== $joinedUser) return null;

        const uid: UserId = nextUserId++;
        const f = t.facet(t => {
            t.assert(o.observer, fromJoin(Join({ uid, handle: ds })));
            let infoHandle: Handle | undefined;
            let nick: string | undefined;
            observe(t, ds, $claimNick, {
                assert(t: Turn, c0: Assertion): void {
                    const c = asNickClaim(c0);
                    if (c.uid !== uid) return;
                    if (nicks.has(c.name)) {
                        t.message(c.k, fromNickConflict(NickConflict()));
                    } else {
                        t.message(c.k, true);
                        if (nick !== void 0) nicks.delete(nick);
                        infoHandle = t.replace(ds, infoHandle, fromUserInfo(UserInfo(c)));
                        nick = c.name;
                        nicks.set(nick, uid);
                    }
                }
            });
        });

        return t => t.stop(f);
    }));
}