import { Injectable, OnDestroy } from "@angular/core";
import { MatSnackBar, MatSnackBarRef } from "@angular/material/snack-bar";
import { Subscription } from "rxjs";

/**
 * Provides an abstract wrapper around showing a MatSnackbar
 * notification based on global environment or API provided
 * configuration.
 *
 * This class Listens for the authentication state to change.
 * Once the state becomes authenticated, retrieve the startup
 * configuration from the API service. Once de-authenticated
 * set the _params to undefined and unsubscribe.
 */
@Injectable({
  providedIn: "root"
})
export class NotificationService implements OnDestroy {
  // Configuration api subscription
  private _configState: Subscription;
  /**
   * Constructor
   * @param toast  {MatSnackBar}
   * @param configService {ConfigurationService}
   */
  constructor(private toast: MatSnackBar) {}

  /**
   * Unsubscribe from the config state
   * when the component is destroyed, and remove
   * the in-memory parameters.
   */
  ngOnDestroy() {
    this._configState.unsubscribe();
  }

  /**
   * Display a MatSnackbar notification and return the reference.
   * Will set the duration to the global configuration if present.
   * @param message {string}
   * @param buttonLabel {string}
   * @returns {MatSnackBarRef}
   */
  show(message: string, buttonLabel: string = "OK"): MatSnackBarRef<any> {
    const toastTimeout = 8000;
    if (toastTimeout > 0) {
      return this.toast.open(message, buttonLabel, {
        duration: toastTimeout
      });
    } else {
      return this.toast.open(message, buttonLabel, {});
    }
  }
}