import Support from '../../../utils/support';

export default function (index = 0, speed = this.params.speed, runCallbacks = true, internal) {
  const swiper = this;
  let slideIndex = index;
  if (slideIndex < 0) slideIndex = 0;

  const {
    params, snapGrid, slidesGrid, previousIndex, activeIndex, rtlTranslate: rtl,
  } = swiper;
  if (swiper.animating && params.preventInteractionOnTransition) {
    return false;
  }

  let snapIndex = Math.floor(slideIndex / params.slidesPerGroup);
  if (snapIndex >= snapGrid.length) snapIndex = snapGrid.length - 1;

  if ((activeIndex || params.initialSlide || 0) === (previousIndex || 0) && runCallbacks) {
    swiper.emit('beforeSlideChangeStart');
  }

  const translate = -snapGrid[snapIndex];

  // Update progress
  swiper.updateProgress(translate);

  // Normalize slideIndex
  if (params.normalizeSlideIndex) {
    for (let i = 0; i < slidesGrid.length; i += 1) {
      if (-Math.floor(translate * 100) >= Math.floor(slidesGrid[i] * 100)) {
        slideIndex = i;
      }
    }
  }
  // Directions locks
  if (swiper.initialized && slideIndex !== activeIndex) {
    if (!swiper.allowSlideNext && translate < swiper.translate && translate < swiper.minTranslate()) {
      return false;
    }
    if (!swiper.allowSlidePrev && translate > swiper.translate && translate > swiper.maxTranslate()) {
      if ((activeIndex || 0) !== slideIndex) return false;
    }
  }

  let direction;
  if (slideIndex > activeIndex) direction = 'next';
  else if (slideIndex < activeIndex) direction = 'prev';
  else direction = 'reset';


  // Update Index
  if ((rtl && -translate === swiper.translate) || (!rtl && translate === swiper.translate)) {
    swiper.updateActiveIndex(slideIndex);
    // Update Height
    if (params.autoHeight) {
      swiper.updateAutoHeight();
    }
    swiper.updateSlidesClasses();
    if (params.effect !== 'slide') {
      swiper.setTranslate(translate);
    }
    if (direction !== 'reset') {
      swiper.transitionStart(runCallbacks, direction);
      swiper.transitionEnd(runCallbacks, direction);
    }
    return false;
  }

  if (speed === 0 || !Support.transition) {
    swiper.setTransition(0);
    swiper.setTranslate(translate);
    swiper.updateActiveIndex(slideIndex);
    swiper.updateSlidesClasses();
    swiper.emit('beforeTransitionStart', speed, internal);
    swiper.transitionStart(runCallbacks, direction);
    swiper.transitionEnd(runCallbacks, direction);
  } else {
    swiper.setTransition(speed);
    swiper.setTranslate(translate);
    swiper.updateActiveIndex(slideIndex);
    swiper.updateSlidesClasses();
    swiper.emit('beforeTransitionStart', speed, internal);
    swiper.transitionStart(runCallbacks, direction);
    if (!swiper.animating) {
      swiper.animating = true;
      if (!swiper.onSlideToWrapperTransitionEnd) {
        swiper.onSlideToWrapperTransitionEnd = function transitionEnd(e) {
          if (!swiper || swiper.destroyed) return;
          if (e.target !== this) return;
          swiper.$wrapperEl[0].removeEventListener('transitionend', swiper.onSlideToWrapperTransitionEnd);
          swiper.$wrapperEl[0].removeEventListener('webkitTransitionEnd', swiper.onSlideToWrapperTransitionEnd);
          swiper.onSlideToWrapperTransitionEnd = null;
          delete swiper.onSlideToWrapperTransitionEnd;
          swiper.transitionEnd(runCallbacks, direction);
        };
      }
      swiper.$wrapperEl[0].addEventListener('transitionend', swiper.onSlideToWrapperTransitionEnd);
      swiper.$wrapperEl[0].addEventListener('webkitTransitionEnd', swiper.onSlideToWrapperTransitionEnd);
    }
  }

  return true;
}
