import { Theme } from './interfaces'

type ThemeUpdateHandler = (theme: Theme) => any

interface ThemeSubscriptions {
    [componentId: string]: ThemeUpdateHandler
}

export class ThemeNotifier {
    public subscriptions: ThemeSubscriptions = {}

    constructor(public theme: Theme) {}

    public setTheme(theme: Theme) {
        this.theme = theme
        Object.values(this.subscriptions)
            .forEach((cb: ThemeUpdateHandler) => cb(theme))
    }

    public subscribe(componentId: string, callback: ThemeUpdateHandler) {
        this.subscriptions[componentId] = callback
    }

    public unsubscribe = (id: string) => {
        delete this.subscriptions[id]
    }
}