/**
 * @module ol/css
 */


/**
 * The CSS class for hidden feature.
 *
 * @const
 * @type {string}
 */
export const CLASS_HIDDEN = 'ol-hidden';


/**
 * The CSS class that we'll give the DOM elements to have them selectable.
 *
 * @const
 * @type {string}
 */
export const CLASS_SELECTABLE = 'ol-selectable';


/**
 * The CSS class that we'll give the DOM elements to have them unselectable.
 *
 * @const
 * @type {string}
 */
export const CLASS_UNSELECTABLE = 'ol-unselectable';


/**
 * The CSS class for unsupported feature.
 *
 * @const
 * @type {string}
 */
export const CLASS_UNSUPPORTED = 'ol-unsupported';


/**
 * The CSS class for controls.
 *
 * @const
 * @type {string}
 */
export const CLASS_CONTROL = 'ol-control';


/**
 * The CSS class that we'll give the DOM elements that are collapsed, i.e.
 * to those elements which usually can be expanded.
 *
 * @const
 * @type {string}
 */
export const CLASS_COLLAPSED = 'ol-collapsed';


/**
 * Get the list of font families from a font spec.  Note that this doesn't work
 * for font families that have commas in them.
 * @param {string} The CSS font property.
 * @return {Object<string>} The font families (or null if the input spec is invalid).
 */
export const getFontFamilies = (function() {
  let style;
  const cache = {};
  return function(font) {
    if (!style) {
      style = document.createElement('div').style;
    }
    if (!(font in cache)) {
      style.font = font;
      const family = style.fontFamily;
      style.font = '';
      if (!family) {
        return null;
      }
      cache[font] = family.split(/,\s?/);
    }
    return cache[font];
  };
})();