Chatto/chatto/src/main/javascript/ts/src/model/UserModel.ts

import { Subject } from "../observe/Observable";
import { Model } from "./AbstractModel";
import { Observer } from "../observe/Observer";

export class UserModel implements Model, Subject {
    /**
  * @type {Observer[]} List of subscribers. In real life, the list of
  * subscribers can be stored more comprehensively (categorized by event
  * type, etc.).
  */
    private observers: Observer[] = [];
    private state: number = 0;

    constructor() { }
    /**
     * The subscription management methods.
     */
    public attach(observer: Observer): void {
        console.log('Subject: Attached an observer.');
        this.observers.push(observer);
    }

    public detach(observer: Observer): void {
        const observerIndex = this.observers.indexOf(observer);
        this.observers.splice(observerIndex, 1);
        console.log('Subject: Detached an observer.');
    }

    /**
     * Trigger an update in each subscriber.
     */
    public notify(): void {
        console.log('Subject: Notifying observers...');
        for (const observer of this.observers) {
            observer.update(this.state);
        }
    }

    public someBusinessMethod(num: number): void {
        this.state = num;
        this.helperMethod();
        console.log(`Subject: My state has just changed to: ${this.state}`);
        this.notify();
    }

    private helperMethod() {}

}