styles.js

import AutoPrefix from '../styles/auto-prefix';
import ImmutabilityHelper from '../utils/immutability-helper';

const reTranslate = /((^|\s)translate(3d|X)?\()(\-?[\d]+)/;

const reSkew = /((^|\s)skew(x|y)?\()\s*(\-?[\d]+)(deg|rad|grad)(,\s*(\-?[\d]+)(deg|rad|grad))?/;

export default {

  mergeAndPrefix() {
    let mergedStyles = ImmutabilityHelper.merge.apply(this, arguments);
    return AutoPrefix.all(mergedStyles);
  },

  // This function ensures that `style` supports both ltr and rtl directions by checking
  //   `styleConstants` in `muiTheme` and replacing attribute keys if necessary.
  ensureDirection(muiTheme, style) {
    if (process.env.NODE_ENV !== 'production') {
      if (style.didFlip) {
        console.warn(new Error('You\'re calling `ensureDirection` on the same style object twice.'));
      }
      style = ImmutabilityHelper.merge({
        didFlip: 'true',
      }, style);
    }

    // Left to right is the default. No need to flip anything.
    if (!muiTheme.isRtl) return style;

    const flippedAttributes = {
      // Keys and their replacements.
      right: 'left',
      left: 'right',
      marginRight: 'marginLeft',
      marginLeft: 'marginRight',
      paddingRight: 'paddingLeft',
      paddingLeft: 'paddingRight',
      borderRight: 'borderLeft',
      borderLeft: 'borderRight',
    };

    let newStyle = {};

    Object.keys(style).forEach(function(attribute) {
      let value = style[attribute];
      let key = attribute;

      if (flippedAttributes.hasOwnProperty(attribute)) {
        key = flippedAttributes[attribute];
      }

      switch (attribute) {
        case 'float':
        case 'textAlign':
          if (value === 'right') {
            value = 'left';
          } else if (value === 'left') {
            value = 'right';
          }
          break;
        case 'direction':
          if (value === 'ltr') {
            value = 'rtl';
          } else if (value === 'rtl') {
            value = 'ltr';
          }
          break;
        case 'transform':
          let matches;
          if ((matches = value.match(reTranslate))) {
            value = value.replace(matches[0], matches[1] + (-parseFloat(matches[4])) );
          }
          if ((matches = value.match(reSkew))) {
            value = value.replace(matches[0], matches[1] + (-parseFloat(matches[4])) + matches[5] +
              matches[6] ? ',' + (-parseFloat(matches[7])) + matches[8] : ''
            );
          }
          break;
        case 'transformOrigin':
          if (value.indexOf('right') > -1) {
            value = value.replace('right', 'left');
          } else if (value.indexOf('left') > -1) {
            value = value.replace('left', 'right');
          }
          break;
      }

      newStyle[key] = value;
    });

    return newStyle;
  },

  prepareStyles(muiTheme, ...styles) {
    styles = styles.length > 1 ? ImmutabilityHelper.merge.apply(this, styles) : (styles[0] || {});
    const flipped = this.ensureDirection(muiTheme, styles);
    return AutoPrefix.all(flipped);
  },
};