class Subscribable {
	constructor() {
		this.events = {
			addSelf: [],
			editSelf: [],
			removeSelf: [],
			changeSelf: []
		}
		this.eventDeps = {
			addSelf: ["changeSelf"],
			editSelf: ["changeSelf"],
			removeSelf: ["changeSelf"],
			changeSelf: []
		}
	}

	subscribe(event, callback) {
		if (this.events[event]) {
			this.events[event].push(callback)
		} else {
			throw new Error(`Cannot subscribe to non-existent event ${event}, available events are: ${Object.keys(this.events).join(", ")}`)
		}
	}

	unsubscribe(event, callback) {
		const index = this.events[event].indexOf(callback)
		if (index === -1) throw new Error(`Tried to remove a nonexisting subscription from event ${event}`)
		this.events[event].splice(index, 1)
	}

	broadcast(event, data) {
		this.eventDeps[event].concat(event).forEach(eventName => {
			this.events[eventName].forEach(f => f(event, data))
		})
	}
}

module.exports = {Subscribable}