/**
 * Copyright (c) Tiny Technologies, Inc. All rights reserved.
 * Licensed under the LGPL or a commercial license.
 * For LGPL see License.txt in the project root for license information.
 * For commercial licenses see https://www.tiny.cloud/
 */

import { Arr, Fun } from '@ephox/katamari';
import { Compare, SugarElement } from '@ephox/sugar';
import * as ElementType from '../dom/ElementType';
import * as Parents from '../dom/Parents';
import * as CaretFinder from './CaretFinder';
import { CaretPosition } from './CaretPosition';
import { isEmptyText } from './CaretPositionPredicates';
import { isInSameBlock } from './CaretUtils';

const navigateIgnoreEmptyTextNodes = (forward: boolean, root: Element, from: CaretPosition) => CaretFinder.navigateIgnore(forward, root, from, isEmptyText);

const getClosestBlock = (root: SugarElement, pos: CaretPosition) => Arr.find(Parents.parentsAndSelf(SugarElement.fromDom(pos.container()), root), ElementType.isBlock);

const isAtBeforeAfterBlockBoundary = (forward: boolean, root: SugarElement, pos: CaretPosition) => navigateIgnoreEmptyTextNodes(forward, root.dom, pos).forall((newPos) => getClosestBlock(root, pos).fold(
  () => isInSameBlock(newPos, pos, root.dom) === false,
  (fromBlock) => isInSameBlock(newPos, pos, root.dom) === false && Compare.contains(fromBlock, SugarElement.fromDom(newPos.container()))
));

const isAtBlockBoundary = (forward: boolean, root: SugarElement, pos: CaretPosition) => getClosestBlock(root, pos).fold(
  () => navigateIgnoreEmptyTextNodes(forward, root.dom, pos).forall((newPos) => isInSameBlock(newPos, pos, root.dom) === false),
  (parent) => navigateIgnoreEmptyTextNodes(forward, parent.dom, pos).isNone()
);

const isAtStartOfBlock = Fun.curry(isAtBlockBoundary, false);
const isAtEndOfBlock = Fun.curry(isAtBlockBoundary, true);
const isBeforeBlock = Fun.curry(isAtBeforeAfterBlockBoundary, false);
const isAfterBlock = Fun.curry(isAtBeforeAfterBlockBoundary, true);

export {
  isAtStartOfBlock,
  isAtEndOfBlock,
  isBeforeBlock,
  isAfterBlock
};
