/**
 * Utility used to transform the `auto` placement to the placement with more
 * available space.
 */
import { getBoundaries } from './getBoundaries';
import { Offsets, PlacementForBs5 } from '../models';
import { getBsVer } from 'ngx-bootstrap/utils';

function getArea({ width, height }: { width: number; height: number }) {
  return width * height;
}

export function computeAutoPlacement(
  placement: string,
  refRect: Offsets,
  target: HTMLElement,
  host: HTMLElement,
  allowedPositions = ['top', 'bottom', 'right', 'left'],
  boundariesElement = 'viewport',
  padding = 0
) {
  if (placement.indexOf('auto') === -1) {
    return placement;
  }

  const boundaries = getBoundaries(target, host, padding, boundariesElement);

  type Rects = { top: Offsets; right: Offsets; bottom: Offsets; left: Offsets };
  const rects: Rects = {
    top: {
      width: boundaries?.width ?? 0,
      height: (refRect?.top ?? 0) - (boundaries?.top ?? 0)
    },
    right: {
      width: (boundaries?.right ?? 0) - (refRect?.right ?? 0),
      height: boundaries?.height ?? 0
    },
    bottom: {
      width: boundaries?.width ?? 0,
      height: (boundaries?.bottom ?? 0) - (refRect?.bottom ?? 0)
    },
    left: {
      width: (refRect.left ?? 0) - (boundaries?.left ?? 0),
      height: boundaries?.height ?? 0
    }
  };

  const sortedAreas = Object.keys(rects)
    .map((key) => ({
      position: key,
      ...rects[key as keyof Rects],
      area: getArea(rects[key as keyof Rects] as { width: number; height: number })
    }))
    .sort((a, b) => b.area - a.area);

  let filteredAreas = sortedAreas.filter(({ width, height }) => {
    return width >= target.clientWidth && height >= target.clientHeight;
  });

  filteredAreas = filteredAreas.filter(({ position }) => {
    return allowedPositions.some((allowedPosition: string) => {
      return allowedPosition === position;
    });
  });

  const computedPlacement: string = filteredAreas.length > 0 ? filteredAreas[0].position : sortedAreas[0].position;

  const variation = placement.split(' ')[1];
  // for tooltip on auto position
  target.className = target.className.replace(
    /bs-tooltip-auto/g,
    `bs-tooltip-${
      getBsVer().isBs5 ? PlacementForBs5[computedPlacement as keyof typeof PlacementForBs5] : computedPlacement
    }`
  );

  return computedPlacement + (variation ? `-${variation}` : '');
}