import { ExtensionItem } from '../src/API'

// Naive signals implementation
interface Signal<T> {
    get(): T
    set(value: T): void
}

let currentEffect: (() => void) | null = null

const signal = <T>(initialValue: T): Signal<T> => {
    let value = initialValue
    const subscribers = new Set<() => void>()

    return {
        get: () => {
            if (currentEffect) {
                subscribers.add(currentEffect)
            }
            return value
        },
        set: (newValue: T) => {
            value = newValue
            subscribers.forEach(fn => fn())
        }
    }
}

const effect = (fn: () => void): (() => void) => {
    const execute = () => {
        currentEffect = execute
        fn()
        currentEffect = null
    }
    execute()
    return () => {
        currentEffect = null
    }
}

export const createSignalItemsDataStructure = () => {
    let signalToTrack: Signal<ExtensionItem<any>[]> | null = null
    return {
        createDataStructure: <U>() => {
            const itemsSignal = signal<ExtensionItem<U>[]>([])
            signalToTrack = itemsSignal
            return {
                get: () => itemsSignal.get(),
                add: (item: ExtensionItem<U>) => {
                    itemsSignal.set([...itemsSignal.get(), item])
                },
                discardBy: (predicate: (item: ExtensionItem<U>) => boolean) => {
                    itemsSignal.set(itemsSignal.get().filter(predicate))
                }
            }
        },
        getSignalToTrack: () => {
            if (!signalToTrack) {
                throw new Error('Signal to track is not set')
            }
            return signalToTrack
        },
        effect
    }
}