Trying to prevent nested table paste via `transformPasted`

6

I have a working implementation now that prevents nested tables and wanted to share it here. I would be curious what others think and if you see room for improvement:

new Plugin({
	key: new PluginKey('preventNestedTables'),
	// Prevent nested table (low level protection): filter out transactions that lead to nested table
	filterTransaction: (transaction) => {
		if (!transaction.docChanged) {
			return true
		}

		let hasNestedTable = false
		transaction.doc.descendants((node, pos) => {
			if (node.type.name.startsWith('table')) {
				const $pos = transaction.doc.resolve(pos)
				for (let depth = $pos.depth; depth >= 0; depth--) {
					const ancestor = $pos.node(depth)
					if (ancestor.type.name === 'tableCell') {
						console.warn(
							'Detected nested table, filtering out transaction',
						)
						hasNestedTable = true
					}
				}
			}
		})

		return !hasNestedTable
	},
	props: {
		// Prevent nested table when pasting to a table cell
		transformPasted: (slice) => {
			if (!this.editor.isActive(this.type.name)) {
				return slice
			}

			let tablePaste = false
			slice.content.descendants((node) => {
				if (node.type.name.startsWith('table')) {
					tablePaste = true
				}
			})

			if (!tablePaste) {
				return slice
			}

			if (
				slice.content.childCount === 1
				&& slice.content.firstChild?.type.name === 'table'
			) {
				const tableChild = slice.content.firstChild.firstChild
				if (
					(tableChild.childCount === 1
						&& tableChild.type.name === 'tableRow')
					|| tableChild.type.name === 'tableHeadRow'
				) {
					const rowChild = tableChild.firstChild
					if (
						(rowChild.childCount === 1
							&& rowChild.type.name === 'tableCell')
						|| rowChild.type.name === 'tableHeader'
					) {
						return new Slice(rowChild.content, 0, 0)
					}
				}
			}

			console.warn('Nested tables are not supported')
			alert(
				t(
					'text',
					'A table was pasted into a table. Nested tables are not supported.',
				),
			)

			const newSlice = new Slice(Fragment.empty, 0, 0)
			return newSlice
		},
	},
})