/**
 * 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 { BlockNodeRecord } from "./BlockNodeRecord";
import type { DraftInlineStyle } from "./DraftInlineStyle";
import type { InlineStyleRange } from "./InlineStyleRange";
import type { List } from "immutable";

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

const findRangesImmutable = require("./findRangesImmutable");

const areEqual = (a, b) => a === b;

const isTruthy = a => !!a;

const EMPTY_ARRAY = [];
/**
 * Helper function for getting encoded styles for each inline style. Convert
 * to UTF-8 character counts for storage.
 */

function getEncodedInlinesForType(block: BlockNodeRecord, styleList: List<DraftInlineStyle>, styleToEncode: string): Array<InlineStyleRange> {
  const ranges = []; // Obtain an array with ranges for only the specified style.

  const filteredInlines = styleList.map(style => style.has(styleToEncode)).toList();
  findRangesImmutable(filteredInlines, areEqual, // We only want to keep ranges with nonzero style values.
  isTruthy, (start, end) => {
    const text = block.getText();
    ranges.push({
      offset: UnicodeUtils.strlen(text.slice(0, start)),
      length: UnicodeUtils.strlen(text.slice(start, end)),
      style: styleToEncode
    });
  });
  return ranges;
}
/*
 * Retrieve the encoded arrays of inline styles, with each individual style
 * treated separately.
 */


function encodeInlineStyleRanges(block: BlockNodeRecord): Array<InlineStyleRange> {
  const styleList = block.getCharacterList().map(c => c.getStyle()).toList();
  const ranges = styleList.flatten().toSet().map(style => getEncodedInlinesForType(block, styleList, style));
  return Array.prototype.concat.apply(EMPTY_ARRAY, ranges.toJS());
}

module.exports = encodeInlineStyleRanges;