import $ from 'jquery';

/**
 * returns whether font is installed or not.
 *
 * @param {String} fontName
 * @return {Boolean}
 */
const genericFontFamilies = ['sans-serif', 'serif', 'monospace', 'cursive', 'fantasy'];

function validFontName(fontName) {
  return ($.inArray(fontName.toLowerCase(), genericFontFamilies) === -1) ? `'${fontName}'` : fontName;
}

function isFontInstalled(fontName) {
  const testFontName = fontName === 'Comic Sans MS' ? 'Courier New' : 'Comic Sans MS';
  const testText = 'mmmmmmmmmmwwwww';
  const testSize = '200px';

  var canvas = document.createElement('canvas');
  var context = canvas.getContext('2d');

  context.font = testSize + " '" + testFontName + "'";
  const originalWidth = context.measureText(testText).width;

  context.font = testSize + ' ' + validFontName(fontName) + ', "' + testFontName + '"';
  const width = context.measureText(testText).width;

  return originalWidth !== width;
}

const userAgent = navigator.userAgent;
const isMSIE = /MSIE|Trident/i.test(userAgent);
let browserVersion;
if (isMSIE) {
  let matches = /MSIE (\d+[.]\d+)/.exec(userAgent);
  if (matches) {
    browserVersion = parseFloat(matches[1]);
  }
  matches = /Trident\/.*rv:([0-9]{1,}[.0-9]{0,})/.exec(userAgent);
  if (matches) {
    browserVersion = parseFloat(matches[1]);
  }
}

const isEdge = /Edge\/\d+/.test(userAgent);

const isSupportTouch =
  (('ontouchstart' in window) ||
   (navigator.MaxTouchPoints > 0) ||
   (navigator.msMaxTouchPoints > 0));

// [workaround] IE doesn't have input events for contentEditable
// - see: https://goo.gl/4bfIvA
const inputEventName = (isMSIE) ? 'DOMCharacterDataModified DOMSubtreeModified DOMNodeInserted' : 'input';

/**
 * @class core.env
 *
 * Object which check platform and agent
 *
 * @singleton
 * @alternateClassName env
 */
export default {
  isMac: navigator.appVersion.indexOf('Mac') > -1,
  isMSIE,
  isEdge,
  isFF: !isEdge && /firefox/i.test(userAgent),
  isPhantom: /PhantomJS/i.test(userAgent),
  isWebkit: !isEdge && /webkit/i.test(userAgent),
  isChrome: !isEdge && /chrome/i.test(userAgent),
  isSafari: !isEdge && /safari/i.test(userAgent) && (!/chrome/i.test(userAgent)),
  browserVersion,
  isSupportTouch,
  isFontInstalled,
  isW3CRangeSupport: !!document.createRange,
  inputEventName,
  genericFontFamilies,
  validFontName,
};