/**
 * Copyright (c) 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule applyEntityToContentState
 * @format
 * @flow
 */

'use strict';

import type ContentState from './ContentState';
import type SelectionState from './SelectionState';

var Immutable = require('immutable');

var applyEntityToContentBlock = require('./applyEntityToContentBlock');

function applyEntityToContentState(contentState: ContentState, selectionState: SelectionState, entityKey: ?string): ContentState {
  const blockMap = contentState.getBlockMap();
  const startKey = selectionState.getStartKey();
  const startOffset = selectionState.getStartOffset();
  const endKey = selectionState.getEndKey();
  const endOffset = selectionState.getEndOffset();

  const newBlocks = blockMap.skipUntil((_, k) => k === startKey).takeUntil((_, k) => k === endKey).toOrderedMap().merge(Immutable.OrderedMap([[endKey, blockMap.get(endKey)]])).map((block, blockKey) => {
    const sliceStart = blockKey === startKey ? startOffset : 0;
    const sliceEnd = blockKey === endKey ? endOffset : block.getLength();
    return applyEntityToContentBlock(block, sliceStart, sliceEnd, entityKey);
  });

  return contentState.merge({
    blockMap: blockMap.merge(newBlocks),
    selectionBefore: selectionState,
    selectionAfter: selectionState
  });
}

module.exports = applyEntityToContentState;