function _extends() {
  _extends = Object.assign || function (target) {
    for (var i = 1; i < arguments.length; i++) {
      var source = arguments[i];

      for (var key in source) {
        if (Object.prototype.hasOwnProperty.call(source, key)) {
          target[key] = source[key];
        }
      }
    }

    return target;
  };

  return _extends.apply(this, arguments);
}

function warning(condition, message) {
  {
    if (condition) {
      return;
    }

    var text = "Warning: " + message;

    if (typeof console !== 'undefined') {
      console.warn(text);
    }

    try {
      throw Error(text);
    } catch (x) {}
  }
}

var separatorRegExp = /\s*,\s*/g;
var parentRegExp = /&/g;
var refRegExp = /\$([\w-]+)/g;
/**
 * Convert nested rules to separate, remove them from original styles.
 */

function jssNested() {
  // Get a function to be used for $ref replacement.
  function getReplaceRef(container, sheet) {
    return function (match, key) {
      var rule = container.getRule(key) || sheet && sheet.getRule(key);

      if (rule) {
        return rule.selector;
      }

       warning(false, "[JSS] Could not find the referenced rule \"" + key + "\" in \"" + (container.options.meta || container.toString()) + "\".") ;
      return key;
    };
  }

  function replaceParentRefs(nestedProp, parentProp) {
    var parentSelectors = parentProp.split(separatorRegExp);
    var nestedSelectors = nestedProp.split(separatorRegExp);
    var result = '';

    for (var i = 0; i < parentSelectors.length; i++) {
      var parent = parentSelectors[i];

      for (var j = 0; j < nestedSelectors.length; j++) {
        var nested = nestedSelectors[j];
        if (result) result += ', '; // Replace all & by the parent or prefix & with the parent.

        result += nested.indexOf('&') !== -1 ? nested.replace(parentRegExp, parent) : parent + " " + nested;
      }
    }

    return result;
  }

  function getOptions(rule, container, prevOptions) {
    // Options has been already created, now we only increase index.
    if (prevOptions) return _extends({}, prevOptions, {
      index: prevOptions.index + 1
    });
    var nestingLevel = rule.options.nestingLevel;
    nestingLevel = nestingLevel === undefined ? 1 : nestingLevel + 1;

    var options = _extends({}, rule.options, {
      nestingLevel: nestingLevel,
      index: container.indexOf(rule) + 1 // We don't need the parent name to be set options for chlid.

    });

    delete options.name;
    return options;
  }

  function onProcessStyle(style, rule, sheet) {
    if (rule.type !== 'style') return style;
    var styleRule = rule;
    var container = styleRule.options.parent;
    var options;
    var replaceRef;

    for (var prop in style) {
      var isNested = prop.indexOf('&') !== -1;
      var isNestedConditional = prop[0] === '@';
      if (!isNested && !isNestedConditional) continue;
      options = getOptions(styleRule, container, options);

      if (isNested) {
        var selector = replaceParentRefs(prop, styleRule.selector); // Lazily create the ref replacer function just once for
        // all nested rules within the sheet.

        if (!replaceRef) replaceRef = getReplaceRef(container, sheet); // Replace all $refs.

        selector = selector.replace(refRegExp, replaceRef);
        var name = styleRule.key + "-" + prop;

        if ('replaceRule' in container) {
          // for backward compatibility
          container.replaceRule(name, style[prop], _extends({}, options, {
            selector: selector
          }));
        } else {
          container.addRule(name, style[prop], _extends({}, options, {
            selector: selector
          }));
        }
      } else if (isNestedConditional) {
        // Place conditional right after the parent rule to ensure right ordering.
        container.addRule(prop, {}, options).addRule(styleRule.key, style[prop], {
          selector: styleRule.selector
        });
      }

      delete style[prop];
    }

    return style;
  }

  return {
    onProcessStyle: onProcessStyle
  };
}

export default jssNested;
