converter/src/app/inputcomponentmanager.service.ts

import {Injectable} from '@angular/core';
import {Step} from './step';

@Injectable()
export class InputComponentManagerService {
  private components: Step[] = [];

  public constructor() {
  }

  public register(component: Step): void {
    this.components.push(component);
  }

  public getAllComponents(): Step[] {
    return this.components;
  }

  public getNext(component: Step): Step {
    const index: number = component.index;
    if (index === this.components.length - 1) {
      this.addComponent();
    }
    return this.components[index + 1];
  }

  public getFirst(): Step {
    if (this.components.length === 0) {
      this.addComponent();
    }
    return this.components[0];
  }

  private addComponent(): void {
    this.register(new Step(this.components.length));
  }
}