/**
 * 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 AtomicBlockUtils
 * @format
 * @flow
 */

'use strict';

import type { BlockNodeRecord } from './BlockNodeRecord';
import type { DraftInsertionType } from './DraftInsertionType';

const BlockMapBuilder = require('./BlockMapBuilder');
const CharacterMetadata = require('./CharacterMetadata');
const ContentBlock = require('./ContentBlock');
const ContentBlockNode = require('./ContentBlockNode');
const DraftFeatureFlags = require('./DraftFeatureFlags');
const DraftModifier = require('./DraftModifier');
const EditorState = require('./EditorState');
const Immutable = require('immutable');
const SelectionState = require('./SelectionState');

const generateRandomKey = require('./generateRandomKey');
const moveBlockInContentState = require('./moveBlockInContentState');

const experimentalTreeDataSupport = DraftFeatureFlags.draft_tree_data_support;
const ContentBlockRecord = experimentalTreeDataSupport ? ContentBlockNode : ContentBlock;

const { List, Repeat } = Immutable;

const AtomicBlockUtils = {
  insertAtomicBlock: function (editorState: EditorState, entityKey: string, character: string): EditorState {
    const contentState = editorState.getCurrentContent();
    const selectionState = editorState.getSelection();

    const afterRemoval = DraftModifier.removeRange(contentState, selectionState, 'backward');

    const targetSelection = afterRemoval.getSelectionAfter();
    const afterSplit = DraftModifier.splitBlock(afterRemoval, targetSelection);
    const insertionTarget = afterSplit.getSelectionAfter();

    const asAtomicBlock = DraftModifier.setBlockType(afterSplit, insertionTarget, 'atomic');

    const charData = CharacterMetadata.create({ entity: entityKey });

    let atomicBlockConfig = {
      key: generateRandomKey(),
      type: 'atomic',
      text: character,
      characterList: List(Repeat(charData, character.length))
    };

    let atomicDividerBlockConfig = {
      key: generateRandomKey(),
      type: 'unstyled'
    };

    if (experimentalTreeDataSupport) {
      atomicBlockConfig = {
        ...atomicBlockConfig,
        nextSibling: atomicDividerBlockConfig.key
      };
      atomicDividerBlockConfig = {
        ...atomicDividerBlockConfig,
        prevSibling: atomicBlockConfig.key
      };
    }

    const fragmentArray = [new ContentBlockRecord(atomicBlockConfig), new ContentBlockRecord(atomicDividerBlockConfig)];

    const fragment = BlockMapBuilder.createFromArray(fragmentArray);

    const withAtomicBlock = DraftModifier.replaceWithFragment(asAtomicBlock, insertionTarget, fragment);

    const newContent = withAtomicBlock.merge({
      selectionBefore: selectionState,
      selectionAfter: withAtomicBlock.getSelectionAfter().set('hasFocus', true)
    });

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

  moveAtomicBlock: function (editorState: EditorState, atomicBlock: BlockNodeRecord, targetRange: SelectionState, insertionMode?: DraftInsertionType): EditorState {
    const contentState = editorState.getCurrentContent();
    const selectionState = editorState.getSelection();

    let withMovedAtomicBlock;

    if (insertionMode === 'before' || insertionMode === 'after') {
      const targetBlock = contentState.getBlockForKey(insertionMode === 'before' ? targetRange.getStartKey() : targetRange.getEndKey());

      withMovedAtomicBlock = moveBlockInContentState(contentState, atomicBlock, targetBlock, insertionMode);
    } else {
      const afterRemoval = DraftModifier.removeRange(contentState, targetRange, 'backward');

      const selectionAfterRemoval = afterRemoval.getSelectionAfter();
      const targetBlock = afterRemoval.getBlockForKey(selectionAfterRemoval.getFocusKey());

      if (selectionAfterRemoval.getStartOffset() === 0) {
        withMovedAtomicBlock = moveBlockInContentState(afterRemoval, atomicBlock, targetBlock, 'before');
      } else if (selectionAfterRemoval.getEndOffset() === targetBlock.getLength()) {
        withMovedAtomicBlock = moveBlockInContentState(afterRemoval, atomicBlock, targetBlock, 'after');
      } else {
        const afterSplit = DraftModifier.splitBlock(afterRemoval, selectionAfterRemoval);

        const selectionAfterSplit = afterSplit.getSelectionAfter();
        const targetBlock = afterSplit.getBlockForKey(selectionAfterSplit.getFocusKey());

        withMovedAtomicBlock = moveBlockInContentState(afterSplit, atomicBlock, targetBlock, 'before');
      }
    }

    const newContent = withMovedAtomicBlock.merge({
      selectionBefore: selectionState,
      selectionAfter: withMovedAtomicBlock.getSelectionAfter().set('hasFocus', true)
    });

    return EditorState.push(editorState, newContent, 'move-block');
  }
};

module.exports = AtomicBlockUtils;