/**
 * 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 SecondaryClipboard
 * @format
 * @flow
 */

'use strict';

import type { BlockMap } from './BlockMap';
import type SelectionState from './SelectionState';

var DraftModifier = require('./DraftModifier');
var EditorState = require('./EditorState');

var getContentStateFragment = require('./getContentStateFragment');
var nullthrows = require('fbjs/lib/nullthrows');

var clipboard: ?BlockMap = null;

/**
 * Some systems offer a "secondary" clipboard to allow quick internal cut
 * and paste behavior. For instance, Ctrl+K (cut) and Ctrl+Y (paste).
 */
var SecondaryClipboard = {
  cut: function (editorState: EditorState): EditorState {
    var content = editorState.getCurrentContent();
    var selection = editorState.getSelection();
    var targetRange: ?SelectionState = null;

    if (selection.isCollapsed()) {
      var anchorKey = selection.getAnchorKey();
      var blockEnd = content.getBlockForKey(anchorKey).getLength();

      if (blockEnd === selection.getAnchorOffset()) {
        return editorState;
      }

      targetRange = selection.set('focusOffset', blockEnd);
    } else {
      targetRange = selection;
    }

    targetRange = nullthrows(targetRange);
    clipboard = getContentStateFragment(content, targetRange);

    var afterRemoval = DraftModifier.removeRange(content, targetRange, 'forward');

    if (afterRemoval === content) {
      return editorState;
    }

    return EditorState.push(editorState, afterRemoval, 'remove-range');
  },

  paste: function (editorState: EditorState): EditorState {
    if (!clipboard) {
      return editorState;
    }

    var newContent = DraftModifier.replaceWithFragment(editorState.getCurrentContent(), editorState.getSelection(), clipboard);

    return EditorState.push(editorState, newContent, 'insert-fragment');
  }
};

module.exports = SecondaryClipboard;