import { DOCUMENT } from '@angular/common';
import { Inject, Injectable } from '@angular/core';
import { EventManager } from '@angular/platform-browser';
import { Observable } from 'rxjs';

interface Options {
  element: any;
  keys: string;
};

@Injectable({ providedIn: 'root' })
export class HotKeysService {
  defaults: Partial<Options> = {
    element: this.document
  };

  constructor(private eventManager: EventManager, @Inject(DOCUMENT) private document: Document) {
  }

  addShortcut(options: Partial<Options>) {
    const merged = { ...this.defaults, ...options };
    const event = `keydown.${merged.keys}`;

    return new Observable(observer => {
      const handler = (e: KeyboardEvent) => {
        const activeElement = this.document.activeElement;
        const notOnInput = activeElement?.tagName !== 'INPUT' && activeElement?.tagName !== 'TEXTAREA';
        if (notOnInput) {
          if (document.URL.endsWith('/slides')) {
            e.preventDefault();
            observer.next(e);
          }
        }
      };

      const dispose = this.eventManager.addEventListener(
        merged.element, event, handler
      );

      return () => {
        dispose();
      };
    });
  }

  scrollToCurrentItem(type: 'slide'|'service', block: 'start'|'center'|'end'|'nearest') {
    document.querySelectorAll(`openlp-${type}-item .selected`)[0]?.scrollIntoView({
        behavior: 'smooth',
        block
    });
  }
}