/**
 * 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";
import type { BlockNodeRecord } from "./BlockNodeRecord";
import type ContentState from "./ContentState";
import type SelectionState from "./SelectionState";

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

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

const Immutable = require("immutable");

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

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

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

const {
  List
} = Immutable;
export type BlockDataMergeBehavior = 'REPLACE_WITH_NEW_DATA' | 'MERGE_OLD_DATA_TO_NEW_DATA';

const updateExistingBlock = (contentState: ContentState, selectionState: SelectionState, blockMap: BlockMap, fragmentBlock: BlockNodeRecord, targetKey: string, targetOffset: number, mergeBlockData?: BlockDataMergeBehavior = 'REPLACE_WITH_NEW_DATA'): ContentState => {
  const targetBlock = blockMap.get(targetKey);
  const text = targetBlock.getText();
  const chars = targetBlock.getCharacterList();
  const finalKey = targetKey;
  const finalOffset = targetOffset + fragmentBlock.getText().length;
  let data = null;

  switch (mergeBlockData) {
    case 'MERGE_OLD_DATA_TO_NEW_DATA':
      data = fragmentBlock.getData().merge(targetBlock.getData());
      break;

    case 'REPLACE_WITH_NEW_DATA':
      data = fragmentBlock.getData();
      break;
  }

  let type = targetBlock.getType();

  if (text && type === 'unstyled') {
    type = fragmentBlock.getType();
  }

  const newBlock = targetBlock.merge({
    text: text.slice(0, targetOffset) + fragmentBlock.getText() + text.slice(targetOffset),
    characterList: insertIntoList(chars, fragmentBlock.getCharacterList(), targetOffset),
    type,
    data
  });
  return contentState.merge({
    blockMap: blockMap.set(targetKey, newBlock),
    selectionBefore: selectionState,
    selectionAfter: selectionState.merge({
      anchorKey: finalKey,
      anchorOffset: finalOffset,
      focusKey: finalKey,
      focusOffset: finalOffset,
      isBackward: false
    })
  });
};
/**
 * Appends text/characterList from the fragment first block to
 * target block.
 */


const updateHead = (block: BlockNodeRecord, targetOffset: number, fragment: BlockMap): BlockNodeRecord => {
  const text = block.getText();
  const chars = block.getCharacterList(); // Modify head portion of block.

  const headText = text.slice(0, targetOffset);
  const headCharacters = chars.slice(0, targetOffset);
  const appendToHead = fragment.first();
  return block.merge({
    text: headText + appendToHead.getText(),
    characterList: headCharacters.concat(appendToHead.getCharacterList()),
    type: headText ? block.getType() : appendToHead.getType(),
    data: appendToHead.getData()
  });
};
/**
 * Appends offset text/characterList from the target block to the last
 * fragment block.
 */


const updateTail = (block: BlockNodeRecord, targetOffset: number, fragment: BlockMap): BlockNodeRecord => {
  // Modify tail portion of block.
  const text = block.getText();
  const chars = block.getCharacterList(); // Modify head portion of block.

  const blockSize = text.length;
  const tailText = text.slice(targetOffset, blockSize);
  const tailCharacters = chars.slice(targetOffset, blockSize);
  const prependToTail = fragment.last();
  return prependToTail.merge({
    text: prependToTail.getText() + tailText,
    characterList: prependToTail.getCharacterList().concat(tailCharacters),
    data: prependToTail.getData()
  });
};

const getRootBlocks = (block: ContentBlockNode, blockMap: BlockMap): Array<string> => {
  const headKey = block.getKey();
  let rootBlock = block;
  const rootBlocks = []; // sometimes the fragment head block will not be part of the blockMap itself this can happen when
  // the fragment head is used to update the target block, however when this does not happen we need
  // to make sure that we include it on the rootBlocks since the first block of a fragment is always a
  // fragment root block

  if (blockMap.get(headKey)) {
    rootBlocks.push(headKey);
  }

  while (rootBlock && rootBlock.getNextSiblingKey()) {
    const lastSiblingKey = rootBlock.getNextSiblingKey();

    if (!lastSiblingKey) {
      break;
    }

    rootBlocks.push(lastSiblingKey);
    rootBlock = blockMap.get(lastSiblingKey);
  }

  return rootBlocks;
};

const updateBlockMapLinks = (blockMap: BlockMap, originalBlockMap: BlockMap, targetBlock: ContentBlockNode, fragmentHeadBlock: ContentBlockNode): BlockMap => {
  return blockMap.withMutations(blockMapState => {
    const targetKey = targetBlock.getKey();
    const headKey = fragmentHeadBlock.getKey();
    const targetNextKey = targetBlock.getNextSiblingKey();
    const targetParentKey = targetBlock.getParentKey();
    const fragmentRootBlocks = getRootBlocks(fragmentHeadBlock, blockMap);
    const lastRootFragmentBlockKey = fragmentRootBlocks[fragmentRootBlocks.length - 1];

    if (blockMapState.get(headKey)) {
      // update the fragment head when it is part of the blockMap otherwise
      blockMapState.setIn([targetKey, 'nextSibling'], headKey);
      blockMapState.setIn([headKey, 'prevSibling'], targetKey);
    } else {
      // update the target block that had the fragment head contents merged into it
      blockMapState.setIn([targetKey, 'nextSibling'], fragmentHeadBlock.getNextSiblingKey());
      blockMapState.setIn([fragmentHeadBlock.getNextSiblingKey(), 'prevSibling'], targetKey);
    } // update the last root block fragment


    blockMapState.setIn([lastRootFragmentBlockKey, 'nextSibling'], targetNextKey); // update the original target next block

    if (targetNextKey) {
      blockMapState.setIn([targetNextKey, 'prevSibling'], lastRootFragmentBlockKey);
    } // update fragment parent links


    fragmentRootBlocks.forEach(blockKey => blockMapState.setIn([blockKey, 'parent'], targetParentKey)); // update targetBlock parent child links

    if (targetParentKey) {
      const targetParent = blockMap.get(targetParentKey);
      const originalTargetParentChildKeys = targetParent.getChildKeys();
      const targetBlockIndex = originalTargetParentChildKeys.indexOf(targetKey);
      const insertionIndex = targetBlockIndex + 1;
      const newChildrenKeysArray = originalTargetParentChildKeys.toArray(); // insert fragment children

      newChildrenKeysArray.splice(insertionIndex, 0, ...fragmentRootBlocks);
      blockMapState.setIn([targetParentKey, 'children'], List(newChildrenKeysArray));
    }
  });
};

const insertFragment = (contentState: ContentState, selectionState: SelectionState, blockMap: BlockMap, fragment: BlockMap, targetKey: string, targetOffset: number): ContentState => {
  const isTreeBasedBlockMap = blockMap.first() instanceof ContentBlockNode;
  const newBlockArr = [];
  const fragmentSize = fragment.size;
  const target = blockMap.get(targetKey);
  const head = fragment.first();
  const tail = fragment.last();
  const finalOffset = tail.getLength();
  const finalKey = tail.getKey();
  const shouldNotUpdateFromFragmentBlock = isTreeBasedBlockMap && (!target.getChildKeys().isEmpty() || !head.getChildKeys().isEmpty());
  blockMap.forEach((block, blockKey) => {
    if (blockKey !== targetKey) {
      newBlockArr.push(block);
      return;
    }

    if (shouldNotUpdateFromFragmentBlock) {
      newBlockArr.push(block);
    } else {
      newBlockArr.push(updateHead(block, targetOffset, fragment));
    } // Insert fragment blocks after the head and before the tail.


    fragment // when we are updating the target block with the head fragment block we skip the first fragment
    // head since its contents have already been merged with the target block otherwise we include
    // the whole fragment
    .slice(shouldNotUpdateFromFragmentBlock ? 0 : 1, fragmentSize - 1).forEach(fragmentBlock => newBlockArr.push(fragmentBlock)); // update tail

    newBlockArr.push(updateTail(block, targetOffset, fragment));
  });
  let updatedBlockMap = BlockMapBuilder.createFromArray(newBlockArr);

  if (isTreeBasedBlockMap) {
    updatedBlockMap = updateBlockMapLinks(updatedBlockMap, blockMap, target, head);
  }

  return contentState.merge({
    blockMap: updatedBlockMap,
    selectionBefore: selectionState,
    selectionAfter: selectionState.merge({
      anchorKey: finalKey,
      anchorOffset: finalOffset,
      focusKey: finalKey,
      focusOffset: finalOffset,
      isBackward: false
    })
  });
};

const insertFragmentIntoContentState = (contentState: ContentState, selectionState: SelectionState, fragmentBlockMap: BlockMap, mergeBlockData?: BlockDataMergeBehavior = 'REPLACE_WITH_NEW_DATA'): ContentState => {
  invariant(selectionState.isCollapsed(), '`insertFragment` should only be called with a collapsed selection state.');
  const blockMap = contentState.getBlockMap();
  const fragment = randomizeBlockMapKeys(fragmentBlockMap);
  const targetKey = selectionState.getStartKey();
  const targetOffset = selectionState.getStartOffset();
  const targetBlock = blockMap.get(targetKey);

  if (targetBlock instanceof ContentBlockNode) {
    invariant(targetBlock.getChildKeys().isEmpty(), '`insertFragment` should not be called when a container node is selected.');
  } // When we insert a fragment with a single block we simply update the target block
  // with the contents of the inserted fragment block


  if (fragment.size === 1) {
    return updateExistingBlock(contentState, selectionState, blockMap, fragment.first(), targetKey, targetOffset, mergeBlockData);
  }

  return insertFragment(contentState, selectionState, blockMap, fragment, targetKey, targetOffset);
};

module.exports = insertFragmentIntoContentState;