beyond/lib/utils/ipc/main/events/sources/source.js

The Full Stack Universal Typescript Framework

module.exports = class {
    #sources;
    #name;
    #fork;

    #listeners = new Set;

    constructor(sources, name, fork) {
        this.#sources = sources;
        this.#name = name;
        this.#fork = fork;

        fork.on('message', this.#onmessage);
    };

    /**
     * Dispatch the event if the forked process is registered to it
     * The execution of this method is made by the index.js file (the sources collection)
     *
     * @param sourceName {string} The name of the process that is sending the event
     * @param event {string} The event name
     * @param message {*} The message to be sent
     */
    emit(sourceName, event, message) {
        const key = `${sourceName}|${event}`;
        if (!this.#listeners.has(key)) return;

        try {
            this.#fork.send({
                type: 'ipc.event.dispatch',
                source: sourceName,
                event: event,
                message: message
            });
        }
        catch (exc) {
            console.warn(
                `Error emitting event ${key} to fork process with name "${this.#name}"`,
                exc.message);
        }
    }

    #onmessage = message => {
        if (typeof message !== 'object') return;

        if (message.type === 'ipc.add.event.listener') {
            if (!message.source || !message.event) {
                console.error('Invalid message of event subscription', message);
                return;
            }

            const key = `${message.source}|${message.event}`;
            if (this.#listeners.has(key)) {
                console.warn(`Event "${key}" already subscribed`);
                return;
            }

            this.#listeners.add(key);
        }
        else if (message.type === 'ipc.remove.event.listener') {
            if (!message.source || !message.event) {
                console.error('Invalid message of event subscription remove', message);
                return;
            }

            const key = `${message.source}|${message.event}`;
            if (!this.#listeners.has(key)) {
                console.warn(`Event "${key}" was not previously subscribed`);
                return;
            }

            this.#listeners.add(key);
        }
        else if (message.type === 'ipc.event.emit') {
            if (!message.event || typeof message.event !== 'string') {
                console.error('Invalid parameters on event emit', message);
                return;
            }

            // This is a method exposed by the sources collection (index.js file)
            // This method will iterate over the sources to dispatch the event to the
            // forked processes that are attached to the event
            this.#sources.emit(this.#name, message.event, message.message);
        }
    }

    destroy() {
        this.#fork.removeListener('message', this.#onmessage);
    }
}