masto/dist/esm/adapters/ws/web-socket-subscription.js

Mastodon API client for JavaScript, TypeScript, Node.js, browsers

import { MastoUnexpectedError } from "../errors/index.js";
import { toAsyncIterable } from "./async-iterable.js";
export class WebSocketSubscription {
    connector;
    counter;
    serializer;
    stream;
    logger;
    params;
    connection;
    constructor(connector, counter, serializer, stream, logger, params) {
        this.connector = connector;
        this.counter = counter;
        this.serializer = serializer;
        this.stream = stream;
        this.logger = logger;
        this.params = params;
    }
    async *values() {
        try {
            this.logger?.log("info", "Subscribing to stream", this.stream);
            for await (this.connection of this.connector) {
                const data = this.serializer.serialize("json", {
                    type: "subscribe",
                    stream: this.stream,
                    ...this.params,
                });
                this.logger?.log("debug", "↑ WEBSOCKET", data);
                this.connection.send(data);
                this.counter.increment(this.stream, this.params);
                const messages = toAsyncIterable(this.connection);
                for await (const message of messages) {
                    const event = this.parseMessage(message.data);
                    if (!this.test(event)) {
                        continue;
                    }
                    this.logger?.log("debug", "↓ WEBSOCKET", event);
                    yield event;
                }
                /* c8 ignore next */
            }
        }
        finally {
            this.unsubscribe();
        }
    }
    unsubscribe() {
        if (!this.connection) {
            return;
        }
        this.counter.decrement(this.stream, this.params);
        if (this.counter.count(this.stream, this.params) <= 0) {
            const data = this.serializer.serialize("json", {
                type: "unsubscribe",
                stream: this.stream,
                ...this.params,
            });
            this.connection.send(data);
        }
        this.connection = undefined;
    }
    [Symbol.asyncIterator]() {
        return this.values();
    }
    [Symbol.dispose]() {
        this.unsubscribe();
    }
    test(event) {
        // subscribe("hashtag", { tag: "foo" }) -> ["hashtag", "foo"]
        // subscribe("list", { list: "foo" })   -> ["list", "foo"]
        const params = this.params ?? {};
        const extra = Object.values(params);
        const stream = [this.stream, ...extra];
        return stream.every((s) => event.stream.includes(s));
    }
    parseMessage(rawEvent) {
        const data = this.serializer.deserialize("json", rawEvent);
        if ("error" in data) {
            throw new MastoUnexpectedError(data.error);
        }
        const payload = data.event === "delete" || data.payload == undefined
            ? data.payload
            : this.serializer.deserialize("json", data.payload);
        return {
            stream: data.stream,
            event: data.event,
            payload: payload,
        };
    }
}