export default function Grid({
  swiper,
  extendParams
}) {
  extendParams({
    grid: {
      rows: 1,
      fill: 'column'
    }
  });
  let slidesNumberEvenToRows;
  let slidesPerRow;
  let numFullColumns;

  const initSlides = slidesLength => {
    const {
      slidesPerView
    } = swiper.params;
    const {
      rows,
      fill
    } = swiper.params.grid;
    slidesPerRow = slidesNumberEvenToRows / rows;
    numFullColumns = Math.floor(slidesLength / rows);

    if (Math.floor(slidesLength / rows) === slidesLength / rows) {
      slidesNumberEvenToRows = slidesLength;
    } else {
      slidesNumberEvenToRows = Math.ceil(slidesLength / rows) * rows;
    }

    if (slidesPerView !== 'auto' && fill === 'row') {
      slidesNumberEvenToRows = Math.max(slidesNumberEvenToRows, slidesPerView * rows);
    }
  };

  const updateSlide = (i, slide, slidesLength, getDirectionLabel) => {
    const {
      slidesPerGroup,
      spaceBetween
    } = swiper.params;
    const {
      rows,
      fill
    } = swiper.params.grid; // Set slides order

    let newSlideOrderIndex;
    let column;
    let row;

    if (fill === 'row' && slidesPerGroup > 1) {
      const groupIndex = Math.floor(i / (slidesPerGroup * rows));
      const slideIndexInGroup = i - rows * slidesPerGroup * groupIndex;
      const columnsInGroup = groupIndex === 0 ? slidesPerGroup : Math.min(Math.ceil((slidesLength - groupIndex * rows * slidesPerGroup) / rows), slidesPerGroup);
      row = Math.floor(slideIndexInGroup / columnsInGroup);
      column = slideIndexInGroup - row * columnsInGroup + groupIndex * slidesPerGroup;
      newSlideOrderIndex = column + row * slidesNumberEvenToRows / rows;
      slide.style.order = newSlideOrderIndex;
    } else if (fill === 'column') {
      column = Math.floor(i / rows);
      row = i - column * rows;

      if (column > numFullColumns || column === numFullColumns && row === rows - 1) {
        row += 1;

        if (row >= rows) {
          row = 0;
          column += 1;
        }
      }
    } else {
      row = Math.floor(i / slidesPerRow);
      column = i - row * slidesPerRow;
    }

    slide.style[getDirectionLabel('margin-top')] = row !== 0 ? spaceBetween && `${spaceBetween}px` : '';
  };

  const updateWrapperSize = (slideSize, snapGrid, getDirectionLabel) => {
    const {
      spaceBetween,
      centeredSlides,
      roundLengths
    } = swiper.params;
    const {
      rows
    } = swiper.params.grid;
    swiper.virtualSize = (slideSize + spaceBetween) * slidesNumberEvenToRows;
    swiper.virtualSize = Math.ceil(swiper.virtualSize / rows) - spaceBetween;
    swiper.wrapperEl.style[getDirectionLabel('width')] = `${swiper.virtualSize + spaceBetween}px`;

    if (centeredSlides) {
      const newSlidesGrid = [];

      for (let i = 0; i < snapGrid.length; i += 1) {
        let slidesGridItem = snapGrid[i];
        if (roundLengths) slidesGridItem = Math.floor(slidesGridItem);
        if (snapGrid[i] < swiper.virtualSize + snapGrid[0]) newSlidesGrid.push(slidesGridItem);
      }

      snapGrid.splice(0, snapGrid.length);
      snapGrid.push(...newSlidesGrid);
    }
  };

  swiper.grid = {
    initSlides,
    updateSlide,
    updateWrapperSize
  };
}