/* eslint no-extend-native: "off" */
if (!String.prototype.includes) {
  String.prototype.includes = function (search, start) {
    "use strict";
    if (typeof start !== "number") {
      start = 0;
    }

    if (start + search.length > this.length) {
      return false;
    }
    return this.indexOf(search, start) !== -1;
  };
}

export function getPrefix() {
  const ua = window.navigator.userAgent;
  let prefix = "";
  if (/MSIE/g.test(ua)) {
    prefix = "-ms-";
  } else if (/Firefox/g.test(ua)) {
    prefix = "-moz-";
  } else if (/(WebKit)/i.test(ua)) {
    prefix = "-webkit-";
  } else if (/Opera/g.test(ua)) {
    prefix = "-o-";
  }
  return prefix;
}

export function flip(o) {
  const flipped = {};
  for (const i in o) {
    if (o.hasOwnProperty(i)) {
      flipped[o[i]] = i;
    }
  }
  return flipped;
}

export function reverseDirection(direction) {
  const mapping = {
    top: "bottom",
    right: "left",
    bottom: "top",
    left: "right",
    "right top": "left bottom",
    "top right": "bottom left",
    "bottom right": "top left",
    "right bottom": "left top",
    "left bottom": "right top",
    "bottom left": "top right",
    "top left": "bottom right",
    "left top": "right bottom",
  };
  return mapping.hasOwnProperty(direction) ? mapping[direction] : direction;
}

export function isDirection(n) {
  const reg = /^(top|left|right|bottom)$/i;
  return reg.test(n);
}