@blocknote/core/src/api/blockManipulation/commands/nestBlock/nestBlock.ts

A "Notion-style" block-based extensible text editor built on top of Prosemirror and Tiptap.

import { Fragment, NodeType, Slice } from "prosemirror-model";
import { EditorState, Transaction } from "prosemirror-state";
import { ReplaceAroundStep } from "prosemirror-transform";

import { BlockNoteEditor } from "../../../../editor/BlockNoteEditor.js";
import { getBlockInfoFromTransaction } from "../../../getBlockInfoFromPos.js";

// TODO: Unit tests
/**
 * This is a modified version of https://github.com/ProseMirror/prosemirror-schema-list/blob/569c2770cbb8092d8f11ea53ecf78cb7a4e8f15a/src/schema-list.ts#L232
 *
 * The original function derives too many information from the parentnode and itemtype
 */
function sinkListItem(itemType: NodeType, groupType: NodeType) {
  return function (state: EditorState, dispatch?: (tr: Transaction) => void) {
    const { $from, $to } = state.selection;
    const range = $from.blockRange(
      $to,
      (node) =>
        node.childCount > 0 &&
        (node.type.name === "blockGroup" || node.type.name === "column"), // change necessary to not look at first item child type
    );
    if (!range) {
      return false;
    }
    const startIndex = range.startIndex;
    if (startIndex === 0) {
      return false;
    }
    const parent = range.parent;
    const nodeBefore = parent.child(startIndex - 1);
    if (nodeBefore.type !== itemType) {
      return false;
    }
    if (dispatch) {
      const nestedBefore =
        nodeBefore.lastChild && nodeBefore.lastChild.type === groupType; // change necessary to check groupType instead of parent.type
      const inner = Fragment.from(nestedBefore ? itemType.create() : null);
      const slice = new Slice(
        Fragment.from(
          itemType.create(null, Fragment.from(groupType.create(null, inner))), // change necessary to create "groupType" instead of parent.type
        ),
        nestedBefore ? 3 : 1,
        0,
      );

      const before = range.start;
      const after = range.end;
      dispatch(
        state.tr
          .step(
            new ReplaceAroundStep(
              before - (nestedBefore ? 3 : 1),
              after,
              before,
              after,
              slice,
              1,
              true,
            ),
          )
          .scrollIntoView(),
      );
    }
    return true;
  };
}

export function nestBlock(editor: BlockNoteEditor<any, any, any>) {
  return editor.exec((state, dispatch) =>
    sinkListItem(
      state.schema.nodes["blockContainer"],
      state.schema.nodes["blockGroup"],
    )(state, dispatch),
  );
}

export function unnestBlock(editor: BlockNoteEditor<any, any, any>) {
  editor._tiptapEditor.commands.liftListItem("blockContainer");
}

export function canNestBlock(editor: BlockNoteEditor<any, any, any>) {
  return editor.transact((tr) => {
    const { bnBlock: blockContainer } = getBlockInfoFromTransaction(tr);

    return tr.doc.resolve(blockContainer.beforePos).nodeBefore !== null;
  });
}

export function canUnnestBlock(editor: BlockNoteEditor<any, any, any>) {
  return editor.transact((tr) => {
    const { bnBlock: blockContainer } = getBlockInfoFromTransaction(tr);

    return tr.doc.resolve(blockContainer.beforePos).depth > 1;
  });
}