/**
 * 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
 * @emails oncall+draft_js
 */
'use strict';

import type { BlockMap } from "./BlockMap";

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

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

const Immutable = require("immutable");

const {
  OrderedMap
} = Immutable;

const randomizeContentBlockNodeKeys = (blockMap: BlockMap): BlockMap => {
  const newKeysRef = {}; // we keep track of root blocks in order to update subsequent sibling links

  let lastRootBlock: ContentBlockNode;
  return OrderedMap(blockMap.withMutations(blockMapState => {
    blockMapState.forEach((block, index) => {
      const oldKey = block.getKey();
      const nextKey = block.getNextSiblingKey();
      const prevKey = block.getPrevSiblingKey();
      const childrenKeys = block.getChildKeys();
      const parentKey = block.getParentKey(); // new key that we will use to build linking

      const key = generateRandomKey(); // we will add it here to re-use it later

      newKeysRef[oldKey] = key;

      if (nextKey) {
        const nextBlock = blockMapState.get(nextKey);

        if (nextBlock) {
          blockMapState.setIn([nextKey, 'prevSibling'], key);
        } else {
          // this can happen when generating random keys for fragments
          blockMapState.setIn([oldKey, 'nextSibling'], null);
        }
      }

      if (prevKey) {
        const prevBlock = blockMapState.get(prevKey);

        if (prevBlock) {
          blockMapState.setIn([prevKey, 'nextSibling'], key);
        } else {
          // this can happen when generating random keys for fragments
          blockMapState.setIn([oldKey, 'prevSibling'], null);
        }
      }

      if (parentKey && blockMapState.get(parentKey)) {
        const parentBlock = blockMapState.get(parentKey);
        const parentChildrenList = parentBlock.getChildKeys();
        blockMapState.setIn([parentKey, 'children'], parentChildrenList.set(parentChildrenList.indexOf(block.getKey()), key));
      } else {
        // blocks will then be treated as root block nodes
        blockMapState.setIn([oldKey, 'parent'], null);

        if (lastRootBlock) {
          blockMapState.setIn([lastRootBlock.getKey(), 'nextSibling'], key);
          blockMapState.setIn([oldKey, 'prevSibling'], newKeysRef[lastRootBlock.getKey()]);
        }

        lastRootBlock = blockMapState.get(oldKey);
      }

      childrenKeys.forEach(childKey => {
        const childBlock = blockMapState.get(childKey);

        if (childBlock) {
          blockMapState.setIn([childKey, 'parent'], key);
        } else {
          blockMapState.setIn([oldKey, 'children'], block.getChildKeys().filter(child => child !== childKey));
        }
      });
    });
  }).toArray().map(block => [newKeysRef[block.getKey()], block.set('key', newKeysRef[block.getKey()])]));
};

const randomizeContentBlockKeys = (blockMap: BlockMap): BlockMap => {
  return OrderedMap(blockMap.toArray().map(block => {
    const key = generateRandomKey();
    return [key, block.set('key', key)];
  }));
};

const randomizeBlockMapKeys = (blockMap: BlockMap): BlockMap => {
  const isTreeBasedBlockMap = blockMap.first() instanceof ContentBlockNode;

  if (!isTreeBasedBlockMap) {
    return randomizeContentBlockKeys(blockMap);
  }

  return randomizeContentBlockNodeKeys(blockMap);
};

module.exports = randomizeBlockMapKeys;