const pubsub = (function() { "use strict";

const topics = [
	"MESSAGES_NEW", // {endpoint, channel_id, create_at, user_id, message}
	"MESSAGES_CHANGED",
	"CHANNELS_NEW",
	"CHANNELS_CHANGED",
	"USERS_NEW",
	"USERS_CHANGED",
	"CHANNEL_MEMBERS_NEW",
	"CHANNEL_MEMBERS_REMOVED",
	"CHANNEL_READ", // {endpoint, channel_id}
	"WINDOW_FOCUSED",
];

let subscribers = Object.create(null);
for (let topic of topics) {
	subscribers[topic] = [];
}


function subscribe(topic, callback) {
	assert(subscribers[topic], `Pubsub topic '${topic}' exists`);

	subscribers[topic].push(callback);
}


function publish(topic, payload) {
	assert(subscribers[topic], `Pubsub topic '${topic}' exists`);

	const amountSubs = subscribers[topic].length;
	if (amountSubs == 0) {
		console.warn(`Pubsub event with topic '${topic}' without any subscribers`);
	} else {
		console.debug(`Pubsub event with topic '${topic}' with ${amountSubs} subscribers`);
	}
	for (let subscriber of subscribers[topic]) {
		subscriber(payload);
	}
}


return {subscribe, publish};

})();