@kiwicom/orbit-components/es/Popover/helpers/calculateVerticalPosition.js

Orbit-components is a React component library which provides developers with the easiest possible way of building Kiwi.com’s products.

import { POSITIONS } from "../consts";

const isInside = (p, canBe) => {
  if (p === POSITIONS.TOP && canBe[p]) {
    return POSITIONS.TOP;
  }

  if (p === POSITIONS.BOTTOM && canBe[p]) {
    return POSITIONS.BOTTOM;
  }

  return false;
};

const calculateVerticalPosition = (desiredPositions, pos) => {
  const canBeInWindow = {
    [POSITIONS.TOP]: pos.containerTop - pos.popoverHeight > pos.windowScrollTop,
    [POSITIONS.BOTTOM]: pos.containerTop - pos.windowScrollTop + pos.containerHeight + pos.popoverHeight < pos.windowHeight
  };
  const canBeInDocument = {
    [POSITIONS.TOP]: pos.containerTop - pos.popoverHeight >= 0,
    [POSITIONS.BOTTOM]: pos.containerTop + pos.containerHeight + pos.popoverHeight < pos.documentHeight
  };
  const possibleWindowPositions = desiredPositions.map(p => isInside(p, canBeInWindow)).filter(p => typeof p === "string");
  const possibleDocumentPositions = desiredPositions.map(p => isInside(p, canBeInDocument)).filter(p => typeof p === "string"); // ordering in POSITIONS const is important

  const posPosition = possibleWindowPositions[0] || possibleDocumentPositions[0];

  if (typeof posPosition === "string") {
    return posPosition;
  }

  return POSITIONS.BOTTOM;
};

export default calculateVerticalPosition;