/**
 * 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 convertFromRawToDraftState
 * @format
 * @flow
 */

'use strict';

import type { BlockMap } from './BlockMap';
import type { BlockNodeConfig } from './BlockNode';
import type CharacterMetadata from './CharacterMetadata';
import type { RawDraftContentBlock } from './RawDraftContentBlock';
import type { RawDraftContentState } from './RawDraftContentState';

const ContentBlock = require('./ContentBlock');
const ContentBlockNode = require('./ContentBlockNode');
const ContentState = require('./ContentState');
const DraftEntity = require('./DraftEntity');
const DraftFeatureFlags = require('./DraftFeatureFlags');
const DraftTreeAdapter = require('./DraftTreeAdapter');
const Immutable = require('immutable');
const SelectionState = require('./SelectionState');

const createCharacterList = require('./createCharacterList');
const decodeEntityRanges = require('./decodeEntityRanges');
const decodeInlineStyleRanges = require('./decodeInlineStyleRanges');
const generateRandomKey = require('./generateRandomKey');
const invariant = require('fbjs/lib/invariant');

const experimentalTreeDataSupport = DraftFeatureFlags.draft_tree_data_support;

const { List, Map, OrderedMap } = Immutable;

const decodeBlockNodeConfig = (block: RawDraftContentBlock, entityMap: *): BlockNodeConfig => {
  const { key, type, data, text, depth } = block;

  const blockNodeConfig: BlockNodeConfig = {
    text,
    depth: depth || 0,
    type: type || 'unstyled',
    key: key || generateRandomKey(),
    data: Map(data),
    characterList: decodeCharacterList(block, entityMap)
  };

  return blockNodeConfig;
};

const decodeCharacterList = (block: RawDraftContentBlock, entityMap: *): List<CharacterMetadata> => {
  const {
    text,
    entityRanges: rawEntityRanges,
    inlineStyleRanges: rawInlineStyleRanges
  } = block;

  const entityRanges = rawEntityRanges || [];
  const inlineStyleRanges = rawInlineStyleRanges || [];

  // Translate entity range keys to the DraftEntity map.
  return createCharacterList(decodeInlineStyleRanges(text, inlineStyleRanges), decodeEntityRanges(text, entityRanges.filter(range => entityMap.hasOwnProperty(range.key)).map(range => ({ ...range, key: entityMap[range.key] }))));
};

const addKeyIfMissing = (block: RawDraftContentBlock): RawDraftContentBlock => {
  return {
    ...block,
    key: block.key || generateRandomKey()
  };
};

/**
 * Node stack is responsible to ensure we traverse the tree only once
 * in depth order, while also providing parent refs to inner nodes to
 * construct their links.
 */
const updateNodeStack = (stack: Array<*>, nodes: Array<*>, parentRef: ContentBlockNode): Array<*> => {
  const nodesWithParentRef = nodes.map(block => {
    return {
      ...block,
      parentRef
    };
  });

  // since we pop nodes from the stack we need to insert them in reverse
  return stack.concat(nodesWithParentRef.reverse());
};

/**
 * This will build a tree draft content state by creating the node
 * reference links into a single tree walk. Each node has a link
 * reference to "parent", "children", "nextSibling" and "prevSibling"
 * blockMap will be created using depth ordering.
 */
const decodeContentBlockNodes = (blocks: Array<RawDraftContentBlock>, entityMap: *): BlockMap => {
  return blocks
  // ensure children have valid keys to enable sibling links
  .map(addKeyIfMissing).reduce((blockMap: BlockMap, block: RawDraftContentBlock, index: number) => {
    invariant(Array.isArray(block.children), 'invalid RawDraftContentBlock can not be converted to ContentBlockNode');

    // ensure children have valid keys to enable sibling links
    const children = block.children.map(addKeyIfMissing);

    // root level nodes
    const contentBlockNode = new ContentBlockNode({
      ...decodeBlockNodeConfig(block, entityMap),
      prevSibling: index === 0 ? null : blocks[index - 1].key,
      nextSibling: index === blocks.length - 1 ? null : blocks[index + 1].key,
      children: List(children.map((child: any) => child.key))
    });

    // push root node to blockMap
    blockMap = blockMap.set(contentBlockNode.getKey(), contentBlockNode);

    // this stack is used to ensure we visit all nodes respecting depth ordering
    let stack = updateNodeStack([], children, contentBlockNode);

    // start computing children nodes
    while (stack.length > 0) {
      // we pop from the stack and start processing this node
      const node: any = stack.pop();

      // parentRef already points to a converted ContentBlockNode
      const parentRef: ContentBlockNode = node.parentRef;
      const siblings = parentRef.getChildKeys();
      const index = siblings.indexOf(node.key);
      const isValidBlock = Array.isArray(node.children);

      if (!isValidBlock) {
        invariant(isValidBlock, 'invalid RawDraftContentBlock can not be converted to ContentBlockNode');
        break;
      }

      // ensure children have valid keys to enable sibling links
      const children = node.children.map(addKeyIfMissing);

      const contentBlockNode = new ContentBlockNode({
        ...decodeBlockNodeConfig(node, entityMap),
        parent: parentRef.getKey(),
        children: List(children.map((child: any) => child.key)),
        prevSibling: index === 0 ? null : siblings.get(index - 1),
        nextSibling: index === siblings.size - 1 ? null : siblings.get(index + 1)
      });

      // push node to blockMap
      blockMap = blockMap.set(contentBlockNode.getKey(), contentBlockNode);

      // this stack is used to ensure we visit all nodes respecting depth ordering
      stack = updateNodeStack(stack, children, contentBlockNode);
    }

    return blockMap;
  }, OrderedMap());
};

const decodeContentBlocks = (blocks: Array<RawDraftContentBlock>, entityMap: *): BlockMap => {
  return OrderedMap(blocks.map((block: RawDraftContentBlock) => {
    const contentBlock = new ContentBlock(decodeBlockNodeConfig(block, entityMap));
    return [contentBlock.getKey(), contentBlock];
  }));
};

const decodeRawBlocks = (rawState: RawDraftContentState, entityMap: *): BlockMap => {
  const isTreeRawBlock = Array.isArray(rawState.blocks[0].children);
  const rawBlocks = experimentalTreeDataSupport && !isTreeRawBlock ? DraftTreeAdapter.fromRawStateToRawTreeState(rawState).blocks : rawState.blocks;

  if (!experimentalTreeDataSupport) {
    return decodeContentBlocks(isTreeRawBlock ? DraftTreeAdapter.fromRawTreeStateToRawState(rawState).blocks : rawBlocks, entityMap);
  }

  return decodeContentBlockNodes(rawBlocks, entityMap);
};

const decodeRawEntityMap = (rawState: RawDraftContentState): * => {
  const { entityMap: rawEntityMap } = rawState;
  const entityMap = {};

  // TODO: Update this once we completely remove DraftEntity
  Object.keys(rawEntityMap).forEach(rawEntityKey => {
    const { type, mutability, data } = rawEntityMap[rawEntityKey];

    // get the key reference to created entity
    entityMap[rawEntityKey] = DraftEntity.__create(type, mutability, data || {});
  });

  return entityMap;
};

const convertFromRawToDraftState = (rawState: RawDraftContentState): ContentState => {
  invariant(Array.isArray(rawState.blocks), 'invalid RawDraftContentState');

  // decode entities
  const entityMap = decodeRawEntityMap(rawState);

  // decode blockMap
  const blockMap = decodeRawBlocks(rawState, entityMap);

  // create initial selection
  const selectionState = blockMap.isEmpty() ? new SelectionState() : SelectionState.createEmpty(blockMap.first().getKey());

  return new ContentState({
    blockMap,
    entityMap,
    selectionBefore: selectionState,
    selectionAfter: selectionState
  });
};

module.exports = convertFromRawToDraftState;