data-controller.ts

import { IDataModel } from './data-model'

// A Data Controller Interface
export interface IDataController {
    // A Subject Interface
    subscribe(observer: IDataModel): void
    unsubscribe(observer: IDataModel): void
    notify(data: number[]): void
}

export class DataController implements IDataController {
    // A Subject (a.k.a Observable)

    static instance: DataController
    #observers: Set<IDataModel> = new Set()

    constructor() {
        if (DataController.instance) {
            return DataController.instance
        }
        DataController.instance = this
    }

    subscribe(observer: IDataModel): void {
        this.#observers.add(observer)
    }

    unsubscribe(observer: IDataModel): void {
        this.#observers.delete(observer)
    }

    notify(data: number[]): void {
        this.#observers.forEach((observer) => {
            observer.notify(data)
        })
    }
}