/**
 * 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';

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

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

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

const removeTextWithStrategy = require("./removeTextWithStrategy");
/**
 * Remove the selected range. If the cursor is collapsed, remove the preceding
 * character. This operation is Unicode-aware, so removing a single character
 * will remove a surrogate pair properly as well.
 */


function keyCommandPlainBackspace(editorState: EditorState): EditorState {
  const afterRemoval = removeTextWithStrategy(editorState, strategyState => {
    const selection = strategyState.getSelection();
    const content = strategyState.getCurrentContent();
    const key = selection.getAnchorKey();
    const offset = selection.getAnchorOffset();
    const charBehind = content.getBlockForKey(key).getText()[offset - 1];
    return moveSelectionBackward(strategyState, charBehind ? UnicodeUtils.getUTF16Length(charBehind, 0) : 1);
  }, 'backward');

  if (afterRemoval === editorState.getCurrentContent()) {
    return editorState;
  }

  const selection = editorState.getSelection();
  return EditorState.push(editorState, afterRemoval.set('selectionBefore', selection), selection.isCollapsed() ? 'backspace-character' : 'remove-range');
}

module.exports = keyCommandPlainBackspace;