import {Injectable} from '@angular/core';
import {Observable, race, timer} from 'rxjs';
import {tap, switchMap, map, retry} from 'rxjs/operators';
import {MatDialog, MatDialogRef, ConfirmationComponent} from '../../shared';

@Injectable()
export class SessionExpirationService {
  private readonly EXPIRATION_TIMEOUT: number = 5000;

  private readonly REDIRECT_TIMEOUT: number = 7000;

  private dialogRef: MatDialogRef<ConfirmationComponent>;

  constructor(private dialog: MatDialog) {}

  public start(): Observable<boolean> {
    // start timer to show the confirmation
    return timer(this.EXPIRATION_TIMEOUT).pipe(
      tap(() => {
        this.dialogRef = this.dialogRef || this.createConfirmation();
      }),
      switchMap(() => {
        return race(
          // user is done if the confirmation is closed
          this.dialogRef.afterClosed().pipe(
            tap(() => this.dialogRef = null),
            map((needMoretime) => {
              // treat 'Yes' answer as an error
              if (needMoretime) {
                throw needMoretime;
              }

              return needMoretime;
            })
          ),
          //  user is done after being idle for REDIRECT_TIMEOUT
          timer(this.REDIRECT_TIMEOUT).pipe(
            tap(() => {
              this.dialogRef.close();
              this.dialogRef = null;
            })
          )
        );
      }),
      // retry confirmation if user needs more time
      retry()
    );
  }

  private createConfirmation(): MatDialogRef<ConfirmationComponent> {
    return this.dialog.open(ConfirmationComponent, {
      width: '300px',
      disableClose: true,
      data: {title: 'Do you need more time?', yesText: 'Yes', noText: 'No, I\'m Done'}
    });
  }
}