/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @flow strict-local
 * @emails oncall+draft_js
 */
'use strict';

import type { DraftInlineStyle } from "./DraftInlineStyle";
import type { InlineStyleRange } from "./InlineStyleRange";

const UnicodeUtils = require("fbjs/lib/UnicodeUtils");

const {
  OrderedSet
} = require("immutable");

const {
  substr
} = UnicodeUtils;
const EMPTY_SET = OrderedSet();
/**
 * Convert to native JavaScript string lengths to determine ranges.
 */

function decodeInlineStyleRanges(text: string, ranges?: Array<InlineStyleRange>): Array<DraftInlineStyle> {
  const styles = Array(text.length).fill(EMPTY_SET);

  if (ranges) {
    ranges.forEach(range => {
      let cursor = substr(text, 0, range.offset).length;
      const end = cursor + substr(text, range.offset, range.length).length;

      while (cursor < end) {
        styles[cursor] = styles[cursor].add(range.style);
        cursor++;
      }
    });
  }

  return styles;
}

module.exports = decodeInlineStyleRanges;