import {  Inject, Injectable, Optional } from '@angular/core';
import { BehaviorSubject, Observable } from 'rxjs';
import { BzThemeConfig, THEME_CONFIG } from './theme.config';

@Injectable({
    providedIn: 'root'
})
export class BzThemeService {

    constructor( @Optional() @Inject(THEME_CONFIG) themeConfig?: BzThemeConfig) {
        if (themeConfig?.theme) { 
            this.theme.next(themeConfig?.theme) 
        }
      }

    private theme: BehaviorSubject<string> = new BehaviorSubject<string>('');
    public THEME_SESSION = 'theme_session';

    /**
     * Listen for theme.
     * 
     * @author Federico Gambardella<federico.gambardella@mice.it>
     */
    public listenTheme(): Observable<string> {
        return this.theme.asObservable();
    }

    /**
     * Sets theme.
     *  
     * @author Federico Gambardella<federico.gambardella@mice.it>
     * @param object 
     */
    public setTheme(value: string) {
        sessionStorage.setItem(this.THEME_SESSION, value);
        this.theme.next(value);
    }

}