import { Location } from "history";
import { map } from "rxjs/operators";
import { BehaviorSubject, Observable } from "rxjs";

export class PageStateService {
    private static instance: PageStateService;

    private readonly location$: BehaviorSubject<Location> = new BehaviorSubject(null);

    public static getInstance(): PageStateService {
        if (!PageStateService.instance) {
            PageStateService.instance = new PageStateService();
        }
        return PageStateService.instance;
    }

    private constructor() {}

    public setLocation(location: Location) {
        this.location$.next(location);
    }

    public getState<T = unknown>(): T {
        return this.location$.getValue().state as T;
    }

    public getRoute(): string {
        return this.location$.value?.pathname;
    }

    public get state$(): Observable<unknown> {
        return this.location$.pipe(map(location => location.state));
    }

    public get route$(): Observable<string> {
        return this.location$.pipe(map(location => location?.pathname));
    }
}