"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.deleteRules = exports.safeInsertRules = exports.sheetForTag = void 0;

/* These are helpers that deal with the insertRule (aka speedy) API
 * They are used in the StyleTags and specifically the speedy tag
 */

/* retrieve a sheet for a given style tag */
const sheetForTag = tag => {
  // $FlowFixMe
  if (tag.sheet) return tag.sheet;
  /* Firefox quirk requires us to step through all stylesheets to find one owned by the given tag */

  const size = document.styleSheets.length;

  for (let i = 0; i < size; i += 1) {
    const sheet = document.styleSheets[i]; // $FlowFixMe

    if (sheet.ownerNode === tag) return sheet;
  }
  /* we should always be able to find a tag */


  throw new Error();
};
/* insert a rule safely and return whether it was actually injected */


exports.sheetForTag = sheetForTag;

const safeInsertRule = (sheet, cssRule, index) => {
  /* abort early if cssRule string is falsy */
  if (!cssRule) return false;
  const maxIndex = sheet.cssRules.length;

  try {
    /* use insertRule and cap passed index with maxIndex (no of cssRules) */
    sheet.insertRule(cssRule, index <= maxIndex ? index : maxIndex);
  } catch (err) {
    /* any error indicates an invalid rule */
    return false;
  }

  return true;
};
/* insert multiple rules using safeInsertRule */


const safeInsertRules = (sheet, cssRules, insertIndex) => {
  /* inject each rule and count up the number of actually injected ones */
  let injectedRules = 0;
  const cssRulesSize = cssRules.length;

  for (let i = 0; i < cssRulesSize; i += 1) {
    const cssRule = cssRules[i];

    if (safeInsertRule(sheet, cssRule, insertIndex + injectedRules)) {
      injectedRules += 1;
    }
  }
  /* return number of injected rules */


  return injectedRules;
};
/* deletes `size` rules starting from `removalIndex` */


exports.safeInsertRules = safeInsertRules;

const deleteRules = (sheet, removalIndex, size) => {
  const lowerBound = removalIndex - size;

  for (let i = removalIndex; i >= lowerBound; i -= 1) {
    sheet.deleteRule(i);
  }
};

exports.deleteRules = deleteRules;