Observable Store service

store.ts

import { Observable, BehaviorSubject } from 'rxjs';
import { distinctUntilChanged } from 'rxjs/operators';

export class Store<T> {
    state$: Observable<T>;
    private _state$: BehaviorSubject<T>;

    protected constructor(initialState: T) {
        this._state$ = new BehaviorSubject(initialState);
        this.state$ = this._state$
            .asObservable()
            .pipe(distinctUntilChanged())
    }
    
    get state(): T {
        return this._state$.getValue();
    }

    setState(nextState: T): void {
        this._state$.next(nextState);
    }

    patchState(patch: any): void {
        const nextState: T = Object.assign({}, this.state, patch);
        this._state$.next(nextState);
    } 
}