import { VideoEvent, UIEvent, EngineState } from '../../../constants';

import View from './loader.view';

import { IEventEmitter } from '../../event-emitter/types';
import { IPlaybackEngine } from '../../playback-engine/types';
import { IPlayerConfig } from '../../../core/config';
import { IRootContainer } from '../../root-container/types';
import { ILoader } from './types';

export const DELAYED_SHOW_TIMEOUT = 100;

export default class Loader implements ILoader {
  static moduleName = 'loader';
  static View = View;
  static dependencies = ['engine', 'eventEmitter', 'config', 'rootContainer'];

  private _eventEmitter: IEventEmitter;
  private _engine: IPlaybackEngine;

  private _delayedShowTimeout: number;
  private _unbindEvents: () => void;

  view: View;
  isHidden: boolean;

  constructor({
    config,
    eventEmitter,
    engine,
    rootContainer,
  }: {
    config: IPlayerConfig;
    eventEmitter: IEventEmitter;
    engine: IPlaybackEngine;
    rootContainer: IRootContainer;
  }) {
    this._eventEmitter = eventEmitter;
    this.isHidden = false;
    this._engine = engine;

    this._bindCallbacks();

    this._initUI();
    this._bindEvents();
    this._hideContent();

    rootContainer.appendComponentElement(this.getElement());

    if (config.hideMainUI) {
      this.hide();
    }
  }

  getElement() {
    return this.view.getElement();
  }

  private _bindCallbacks() {
    this._showContent = this._showContent.bind(this);
    this._hideContent = this._hideContent.bind(this);
  }

  private _bindEvents() {
    this._unbindEvents = this._eventEmitter.bindEvents(
      [
        [VideoEvent.STATE_CHANGED, this._checkForWaitingState],
        [VideoEvent.UPLOAD_SUSPEND, this.hide],
      ],
      this,
    );
  }

  private _checkForWaitingState({ nextState }: { nextState: EngineState }) {
    switch (nextState) {
      case EngineState.SEEK_IN_PROGRESS:
        this.startDelayedShow();
        break;
      case EngineState.WAITING:
        this.startDelayedShow();
        break;
      case EngineState.LOAD_STARTED:
        if (this._engine.isPreloadActive) {
          this._showContent();
        }
        break;
      case EngineState.READY_TO_PLAY:
        this.stopDelayedShow();
        this._hideContent();
        break;
      case EngineState.PLAYING:
        this.stopDelayedShow();
        this._hideContent();
        break;
      case EngineState.PAUSED:
        this.stopDelayedShow();
        this._hideContent();
        break;

      /* ignore coverage */
      default:
        break;
    }
  }

  private _initUI() {
    this.view = new Loader.View();
  }

  private _showContent() {
    if (this.isHidden) {
      this._eventEmitter.emitAsync(UIEvent.LOADER_SHOW);
      this.view.showContent();
      this.isHidden = false;
    }
  }

  private _hideContent() {
    if (!this.isHidden) {
      this._eventEmitter.emitAsync(UIEvent.LOADER_HIDE);
      this.view.hideContent();
      this.isHidden = true;
    }
  }

  hide() {
    this.view.hide();
  }

  show() {
    this.view.show();
  }

  startDelayedShow() {
    if (this.isDelayedShowScheduled) {
      this.stopDelayedShow();
    }
    this._delayedShowTimeout = window.setTimeout(
      this._showContent,
      DELAYED_SHOW_TIMEOUT,
    );
  }

  stopDelayedShow() {
    window.clearTimeout(this._delayedShowTimeout);
    this._delayedShowTimeout = null;
  }

  get isDelayedShowScheduled() {
    return Boolean(this._delayedShowTimeout);
  }

  destroy() {
    this._unbindEvents();
    this.stopDelayedShow();

    this.view.destroy();
  }
}