export class State<T> {
    subscribers = new Map<Symbol, SubscribeCallback<T>>();
    value: T

    constructor(value: T) {
        this.value = value;
    }

    set(value: T) {
        this.value = value;
        for (const [_, subscriber] of this.subscribers) {
            subscriber(value)
        }
    }

    update(callback: (currentValue: T) => T) {
        this.set(callback(this.value))
    }

    subscribe(subscriber: SubscribeCallback<T>) {
        const subscriberSymbol = Symbol(subscriber.name)
        this.subscribers.set(subscriberSymbol, subscriber);
        subscriber(this.value);
        return subscriberSymbol;
    }

    unsubscribe(subscriberSymbol: Symbol) {
        this.subscribers.delete(subscriberSymbol);
    }
}

type SubscribeCallback<T> = (value: T) => any
export type ValuesOfStateArray<T extends State<any>[]> = { [K in keyof T]: T[K] extends State<infer V> ? V : never };