import * as Y from 'yjs' // v13.6.30

const UNDO_ORIGIN = Symbol()

const yDoc = new Y.Doc()
const paragraph = yDoc.getText()

const undoManager = new Y.UndoManager(paragraph, {
  trackedOrigins: new Set([UNDO_ORIGIN]),
})

// It's important to apply the format in two steps so that the two
// { bold: { active: false } } objects are different
paragraph.insert(0, 'one two three', { bold: { active: false } })
paragraph.format(4, 9, { bold: { active: true } })
paragraph.format(7, 6, { bold: { active: false } })

paragraph.observe(event => {
  event.changes // Cause the internal data structure to be normalised
})

// The ContentFormat for { bold: { active: false } } is erroneously deleted as
// part of a separate transaction with an origin of null
yDoc.transact(() => paragraph.delete(2, 9), UNDO_ORIGIN)

// The UndoManager successfully undoes everything except the deletion of the
// ContentFormat for { bold: { active: false } }
undoManager.undo()

console.dir(paragraph.toDelta(), { depth: null })

[
  { insert: 'one ', attributes: { bold: { active: false } } },
  { insert: 'two three', attributes: { bold: { active: true } } }
  { insert: ' three', attributes: { bold: { active: false } } }
]

[
  { insert: 'one ', attributes: { bold: { active: false } } },
  { insert: 'two three', attributes: { bold: { active: true } } }
]

import * as Y from 'yjs'

const yDoc = new Y.Doc({ gc: false })
const paragraph = yDoc.get()

paragraph.insert(0, 'one two three', { bold: { active: false } })
paragraph.format(4, 9, { bold: { active: true } })
paragraph.format(7, 6, { bold: { active: false } })
paragraph.delete(2, 9)

for (let item = paragraph._start; item; item = item.right) {
  const description = item.content instanceof Y.ContentString
    ? JSON.stringify(item.content.str)
    : `${item.content.key} = ${JSON.stringify(item.content.value)}`
  const deletedLabel = item.deleted ? ' (deleted)' : ''
  console.log(`${item.id.clock}: ${description}${deletedLabel}`)
}